BRE
Garston, Watford, WD2 7JR
1999
Radon:
guidance on
protective measures
for new dwellings
constructing the future
Prices for all available
BRE publications can
be obtained from:
CRC Ltd
151 Rosebery Avenue
London
EC1R 4GB
Tel 0171 505 6622
Fax 0171 505 6606
E-mail
[email protected]
BR211
ISBN 1 86081 328 3
© Crown copyright 1999
First published 1991
Reprinted 1993 with 1992
revisions
Third edition 1999
Published by
Construction Research
Communications Ltd
for the Department of the
Environment, Transport
and the Regions under
licence from the Controller
of Her Majesty’s Stationery
Office
Applications for
reproduction should be
made in writing to:
The Copyright Unit,
Her Majesty’s Stationery
Office, St Clements House,
2–16 Colegate, Norwich,
NR3 1BQ
Reports on CD
BRE material is also published quarterly on CD
Each CD contains:
● BRE reports published in the current year
(accumulating throughout the year)
● A special feature:
usually a themed compilation of BRE publications
(for example on foundations or timber decay)
The CD collection gives you the opportunity to build a
comprehensive library of BRE material at a fraction of
the cost of printed copies.
As a subscriber you also benefit from a 20% discount
on other BRE titles.
For more information contact:
CRC Customer Services on 0171 505 6622
Construction Research Communications
CRC supplies a wide range of building and
construction related information products from
BRE and other highly respected organisations.
Contact:
by post: CRC Ltd
151 Rosebery Avenue
London EC1R 4GB
by fax:
0171 505 6606
by phone: 0171 505 6622
by email: [email protected]
iii
Contents
Introduction
1
Protective measures
3
Determining the level of protection
Maps in this report
Using the maps to determine level of protection needed
4
4
5
Protective measures: technical approach
Basic radon protection
Full radon protection
7
7
9
Detailed protective measures
Radon-proof barriers
Radon protection to cavities
Lapping and sealing of membranes and trays
Continuity of barriers through internal walls
Continuity of barriers through party or separating walls
Service penetrations
Tanking to basements and cellars
Slip or shear planes
Blinding
Reinforced slabs
Accessible thresholds
Condensation and cold bridges
Subfloor ventilation
Subfloor depressurisation
Sump construction
Edge-located sumps
Fan location
Other points to consider with sumps
Passive stack subfloor depressurisation
High water-table
Garages
Extensions
Landfill gas and radon
Monitoring of completed houses
12
12
13
13
14
14
14
14
15
15
15
15
15
16
16
17
18
18
19
19
19
19
19
20
20
Stepped foundations: additional points to consider
21
Acknowledgements
22
Further information
22
References and further reading
22
Annex A Maps of areas where basic or full protection should be provided
23
Annex B Maps of areas where a geological assessment should be carried out 37
1
Introduction
This report gives guidance for reducing the concentration of radon in new
dwellings, hence reducing the risk to occupants of exposure to radon. It
provides practical details on methods of protecting new dwellings. This
1999 edition of the report replaces guidance published in 1991 for Cornwall
and Devon and revised in 1992 to include parts of Somerset, Derbyshire and
Northamptonshire.
The principal changes over previous editions reflect greater knowledge of
radon-prone areas and the advances made in developing practical costeffective protective measures. In addition, the development of the protective
measures and the monitoring of their effectiveness has indicated that the
general approach to radon protection should be reconsidered and should
embody the findings of this research.
Radon is a colourless, odourless gas which is radioactive. It is formed where
uranium and radium are present and can move through cracks and fissures in
the subsoil, and so into the atmosphere or into spaces under and in dwellings
(Figure 1). Where it occurs in high concentrations it can pose a risk to health.
Whilst it is recognised that the air inside every house contains radon, some
built in certain defined areas of the country might have unacceptably high
concentrations unless precautions are taken. In the UK, the granite areas of
South-West England are of principal concern, but high concentrations of
Key to ingress routes
1 Through cracks in solid floors
2 Through construction joints
3 Through cracks in walls below ground level
4 Through gaps in suspended floors
5 Through cracks in walls
6 Through gaps around service pipes
7 Through cavities in walls
Figure 1 Routes by which radon enters a dwelling
2
Introduction
radon are also found in some other parts of the country.
Requirement C2 of Schedule 1 of the Building Regulations 1991[1] for
England and Wales states that: ‘Precautions shall be taken to avoid danger to
health and safety caused by substances found on or in the ground to be
covered by the building’. The Approved Document[2] states that: ‘The precise
areas where measures should be taken to provide protection against radon are
reviewed by the Department of the Environment, Transport and the Regions
(DETR) in the light of advice from the National Radiological Protection
Board as this becomes available’. The Approved Document refers to the
present report for detailed guidance on where such protection is necessary
and for construction details.
Although this report offers guidance in support of the Building Regulations
for England and Wales, the technical solutions described are equally
applicable for use in Northern Ireland, the Channel Islands and other
countries where construction methods are similar to those in the UK.
Guidance for Scotland, based on this report, is in preparation.
No guidance is currently supplied for suspended timber ground floors in
new dwellings. The DETR is sponsoring research into how this form of
construction could provide adequate protection against radon and will
publish the results in due course.
This guidance was not prepared for non-domestic buildings. However,
protection from radon at work is specified in the Ionising Radiations
Regulations 1985[3], legislation made under the Health and Safety at Work
Act[4] administered by the Health and Safety Executive (HSE). The technical
guidance contained in the present report may be of use to designers and
builders of new structures whose form of construction and compartmentation
is similar to housing and where the heating and ventilation regime is similar to
that used in housing. This is likely to include small office buildings and
primary schools. Further information is contained in the HSE/BRE guide
Radon in the workplace.
3
Protective measures
Radon enters a building primarily by airflow from the underlying ground.
There are two main methods of achieving radon protection in new dwellings:
passive and active. The passive system involves providing a barrier to the
radon (Figure 2). This can usually be achieved by increasing the general
airtightness of the damp protection provided in floors and walls. The active
system consists of providing natural or mechanical underfloor ventilation, or a
powered radon extraction system, as an integral part of the services of the
building. The last two options will incur running and maintenance costs for
the life of the building. Passive systems are to be preferred in new houses,
although they may need to be supplemented in some areas with provision for
active protection.
In areas with a significant radon potential, sufficient protection will be
provided by a well installed damp-proof membrane modified and extended to
form a radon-proof barrier across the ground floor of the dwelling. This is
known as basic radon protection.
New dwellings in areas of higher radon potential should incorporate full
radon protection comprising a radon-proof barrier across the ground floor
supplemented by provision for subfloor depressurisation or ventilation (either
a radon sump or a ventilated subfloor void).
Figure 2 Passive measures to prevent radon entry
4
Determining the level of
protection
Maps in this report
In most cases it is impractical to assess the severity of a radon problem on a
particular site accurately until the building has been constructed and
occupied. Protective measures should therefore be provided in areas with an
identified radon potential. Such areas are shown on the maps in Annexes A
and B as 5 km grid squares. These 5 km grid squares are based on the National
Grid used by the Ordnance Survey so can be easily cross-referenced to local
area Ordnance Survey maps at scales used for planning purposes (eg 1:50 000,
1:25 000 or 1:10 000).
There are two sets of maps in this report:
● Map 1 and Plates 1 to 11 (Annex A) are derived from statistical analysis of
radon measurements of existing houses carried out by the National
Radiological Protection Board (NRPB).
● Map 2 and Plates 12 to 22 (Annex B) are based on assessment of geological
radon potential prepared by the British Geological Survey (BGS).
The two sets of maps are quite different because of the way in which they
have been prepared:
● Map 1 and Plates 1 to 11 are based on a statistical analysis of radon
measurements in houses grouped by 5 km grid squares.
● Map 2 and Plates 12 to 22 are based on a statistical analysis of the same
radon measurements grouped by geological unit; they show those grid
squares which are underlain, completely or in part, by geological units
which potentially exceed the action levels for either basic or full radon
protection. The shading on these maps shows the highest geological radon
potential which has been found within each grid square. As a result there
are many more grid squares shown on these maps than on those in Map 1
and Plates 1 to 11.
If a site falls within a shaded grid square on the BGS maps (Annex B), that
does not necessarily mean that it must have radon protection. This is because
some of the grid squares contain bed rocks and unconsolidated (drift) deposits
with lower radon potential than the maximum levels shown on the map. In
many cases the geological radon potential varies considerably within a grid
square. In other cases, only a very small area (sometimes only a few hundred
square metres) with a radon potential exceeding the thresholds for basic or
full protection occurs within the grid square but, as the squares are coded
according to the highest radon potential, the whole square has been shaded.
The level of protection needed is site specific and can be determined by
reference to the relevant radon potential map followed by a geological
assessment of the site. This information is held by BGS on behalf of DETR in
the Radon Protective Measures Geographical Information System (RPM-GIS).
The areas will need to be revised as more information becomes available
Using the maps to determine level of protection needed
5
from NRPB or BGS. The maps will be amended accordingly. The local
authority for the district in which you are proposing to build, or your Building
Regulations approving body, will be able to confirm which are the latest maps
that should be used.
Using the maps to determine level of protection needed
Both sets of maps are needed to determine the level of protection for a given
site. If Plates 1 to 11 are used in isolation there is a risk that some sites within a
grid square would not be provided with sufficient radon protection (that is
they would be underprotected). Plates 12 to 22 should not be used without
Plates 1 to 11 because they show the highest level of radon potential, and thus
their use in isolation could lead to overprotection.
When the maps are used, the following two-stage procedure (also set out
in the flow chart in Figure 3) should be followed.
Stage 1 — See maps in Annex A
● Using Plates 1 to 11, find the location of the site.
● If the site is in a light brown grid square, basic radon protection should be installed — but
also refer to Annex B to see whether geological data should be sought to determine whether
full protection should be considered.
● If the site is in a dark brown grid square, full radon protection should be provided.
These measures apply to any dwelling that falls wholly or partly within a coloured grid square on
the maps in Annex A.
Stage 2 — See maps in Annex B
● If the site is in a light brown grid square or in a square which is not coloured in Plates 1 to 11,
check if the site is in a shaded grid square on Plates 12 to 22.
● If the site is in a lightly shaded square, basic radon protection may be required. A geological
assessment should be carried out and consideration given to installing basic measures if
the assessment shows that they are necessary.
● If the site is in a dark shaded square, some of the area may have high radon potential. A
geological assessment should be carried out. If the geological assessment shows that
there is a probability that 3–10% of houses in the area will exceed the action level for radon
protection, then basic protection is indicated. If the assessment shows that more than 10%
of the houses will exceed the action level, full protection is indicated. Consideration should
then be given to providing the level of protection indicated by the assessment.
When the level of radon protection has been determined by geological assessment, it only
applies to sites underlain by a geological unit of elevated radon potential and not to all sites in
the grid square.
If the site is in a square that is not coloured or shaded in either set of maps, then no
radon protection is needed.
A geological assessment involves checking whether a site is on or close to a
geological unit with elevated radon potential. BGS has linked geological units
of elevated radon potential to their digitised maps. This has produced the
Radon Protective Measures Geographical Information System (RPM-GIS).
Radon Protective Measures (RPM) site reports may be obtained from:
Central Enquiry Service
British Geological Survey
Keyworth
Nottingham, NG12 5GG
Telephone: 0115 936 3143; Fax: 0115 936 3276; e-mail: [email protected]
An on-line ordering facility will be available in the near future from Services on
the BGS web site http://www.bgs.ac.uk
There are also other institutions, such as universities, who may be able to
provide this information on a local basis.
6
Determining the level of protection
First refer to the maps in Annex A:
Yes
Is the dwelling being built
in a dark brown square?
Install full protection
No need to refer to
Annex B
No
No
Yes
Is the dwelling being built
in a light brown square?
Refer to Annex B to see whether
geological data should be sought to
establish if basic or full protection
should be considered
Install basic protection and refer to
Annex B to see whether geological
data should be sought to establish if
full protection should be considered
Now refer to the maps in Annex B:
Is the dwelling being built
in a dark shaded square?
No
No
Is the dwelling being built
in a lightly shaded square?
No protection
is needed
Yes
Yes
Consideration should be given to
geological data and whether full or
basic protection might be necessary
Consideration should be given to
geological data and whether basic
protection might be necessary
Figure 3 How to use the maps in Annexes A and B to decide what level of protection is necessary in a new dwelling
7
Protective measures:
technical approach
Note on illustrations
The figures included in this guidance only
illustrate the principles of providing a radonproof barrier and supplementary subslab
ventilation. For clarity the positioning of
damp protection, insulation, method of
support of the cavity tray, etc, may have
been omitted. They should not be
considered working drawings. It is the
designer’s responsibility to develop final
details suitable for individual buildings.
Basic radon protection
Requirement C4 of Schedule 1 of the Building Regulations 1991[1] requires
protection against moisture from the ground. In some ground floor
construction, this protection comprises a barrier laid within the floor
construction which is linked to a damp-proof course (dpc) within the walls of
the dwelling; to provide protection from radon, the dpc to a cavity wall should
be in the form of a cavity tray to prevent radon entering the building through
the cavity. Sealing of joints in the barrier and sealing around service
penetrations are also required.
If good standards of design and workmanship are applied to the provision
of the damp-proof barrier to the floor and walls, adequate protection from
radon will be provided along with the general function of excluding moisture.
However, in areas with higher radon emission the additional measures
described in the later section Full radon protection will be required.
Basic radon protection: suspended (beam-and-block) concrete floor
In the example illustrated in Figure 4, a radon-proof barrier is provided by a
vapour-proof membrane which is placed above a suspended concrete floor
and linked to a cavity tray in the external walls. The joints between the sheets
which form the membrane and the cavity tray must be sealed to make the
construction as gas-tight as possible. Seals should also be provided at service
penetrations.
Radon barrier
Floor topping
Air gap
Cavity tray
Suspended
concrete floor
Cavity filled to
support cavity tray
Figure 4 Enhanced damp-proof membrane providing basic radon protection to a
suspended concrete floor
8
Protective measures: technical approach
Basic radon protection: in-situ (ground-supported) concrete floor
In the examples illustrated in Figures 5 and 6, the damp-proof membrane
provides a radon-proof barrier. The joints between the membrane must be
sealed to make them as gas-tight as possible. Service penetrations should also
be sealed and the cavity tray must be joined to the floor membrane and sealed.
Radon barrier
Floor topping
In-situ concrete
floor slab
Cavity tray
dpc
Figure 5 Enhanced damp-proof membrane providing basic radon protection to an
in-situ or ground-supported concrete floor with barrier placed over the slab
Radon barrier
Floor topping
Cavity tray
In-situ concrete
floor slab
dpc
(a) Enhanced damp-proof membrane providing basic radon protection
Floor topping
Radon barrier
dpc
In-situ
concrete
floor slab
Cavity tray
Blinding
Hardcore
Cavity tray sealed to
radon barrier in internal
leaf of external wall
(b) Possible working detail of enhanced damp-proof membrane
Figure 6 Enhanced damp-proof membrane providing basic radon protection to an
in-situ or ground-supported concrete floor with barrier placed beneath the slab
Full radon protection
9
Full radon protection
For areas where the radon risk is higher, further protection than that offered
by the basic radon protection will be needed. It is especially important that
attention should be paid to detailing and workmanship in jointing of the
barrier, and to ensure that the barrier is sealed across the whole of the
building (including the cavity walls).
In areas where there are higher levels of radon, minor imperfections in the
damp-proof membrane in the floor, which also acts as a radon-proof barrier,
may let through sufficient radon to cause the action level to be exceeded. In
these higher radon areas the quantity of radon reaching the barrier can be
reduced through the provision of active protection (either a radon sump or a
ventilated subfloor void).
Full radon protection: suspended concrete (beam-and-block) floor
In the example illustrated in Figure 7, the radon-proof barrier is positioned
over the floor structure and linked to cavity trays at the edges. Supplementary
protection is also provided by locating underfloor vents on two or more sides
of the underfloor space. Although underfloor ventilation reduces the amount
of radon that the radon-proof barrier provided in the floor construction has to
exclude, it should not be looked upon as a primary defence. It is of paramount
importance that damp-proof membranes, which also provide the radonproof barrier, are properly designed and installed. If it is found, through
testing after occupation, that the dwelling still has an unacceptably high radon
level, the rate of ventilation and radon dispersion can be supplemented by the
installation of an electrically powered fan. The fan is not required to be
installed during construction.
Position for
optional fan
if needed
later
Radon barrier
Floor topping
Air gap
Suspended
concrete floor
Air vent
(a) Full radon protection in suspended concrete floor
Floor topping
Insulation
Cavity tray
Weephole
Position for
optional fan
if needed later
Radon barrier
sealed to
cavity tray
Suspended
concrete floor
Air vent
Cavity filled
to support
cavity tray
(b) Possible working detail
Figure 7 Full radon protection in suspended concrete floor
10
Protective measures: technical approach
Full radon protection: in-situ (ground-supported) concrete floor
In the example illustrated in Figure 8, the radon-proof barrier is laid beneath
the oversite concrete and continues across the cavity wall. Note that the
barrier may also be placed above the slab. The slab needs to be reinforced and
is supported on the inner leaf of the cavity wall, since a traditional groundbearing slab could settle on completion and rupture the radon-proof barrier at
the point where the slab meets the external wall. Alternatively, the example in
Figure 9 illustrates the radon-proof barrier laid over the oversite concrete and
continuing across the cavity. Again, the slab needs to be reinforced and is
supported on the inner leaf of the cavity wall.
Supplementary protection is provided to ground-supported concrete floors
by installing a subfloor depressurisation system. If an edge-located sump has
been provided it will need to be connected to a fan and a vertical discharge
pipe. It is possible to use the passive stack ventilation principle to disperse
radon from centrally installed sumps rather than use an electrically powered
fan. However, only the sump and underground pipework need be provided
during construction. This gives the house owner the option of connecting a
fan at a later date if testing after occupation indicates that it is necessary.
These examples are not the only design options available; alternative
solutions may be adopted, such as raft foundations, fully tanked basement
(eg fully waterproofed using asphalt), etc.
Alternative position for subfloor
depressurisation pipe. Pipe must be
sealed where it penetrates the membrane
Radon barrier
Subfloor
depressurisation
pipe
Floor
topping
In-situ
concrete
floor slab
dpc
Cavity
tray
Figure 8 Full radon protection for an in-situ or ground-supported concrete floor (barrier
under slab)
Full radon protection
11
Radon barrier
Cavity tray
Subfloor
depressurisation
pipe
Floor
topping
Alternative position for subfloor depressurisation pipe.
Pipe must be sealed where it penetrates the membrane
In-situ
concrete
floor slab
dpc
(a) Enhanced damp-proof membrane and sump providing full radon protection
Subfloor
depressurisation
pipe
Floor topping
Insulation
dpc
Cavity tray
Radon barrier
Weephole
In-situ concrete
floor slab
(b) Working detail for enhanced damp-proof membrane
Figure 9 Full radon protection for an in-situ or ground-supported concrete floor (barrier
over slab)
12
Detailed protective
measures
Once the method by which protection is to be provided has been decided, the
following detailed guidance will need to be considered.
Radon-proof barriers
Generally a membrane of 300 micrometre (1200 gauge) polyethylene
(Polythene) sheet will be adequate. (It is acknowledged that some diffusion
will occur through the sheet. However, as most radon entry is through cracks,
this diffusion can be ignored.) Where there is a risk of puncturing the
membrane, reinforced polyethylene sheet should be considered.
The barrier can be constructed with other materials which match the
airtightness and waterproofing properties offered by 300 micrometre
(1200 gauge) polyethylene. Alternative materials that can prove suitable
include modern flexible sheet roofing materials, prefabricated welded
barriers, liquid coatings, self-adhesive bituminous-coated sheet products and
asphalt. Prefabricated welded barriers are likely to offer a greater confidence
in achieving radon-proof joints than the use of polyethylene sheet, but are
more expensive. One solution which has been found to be effective is to use
polyethylene sheet over the bulk area of the floor, with a more robust material
suitable for use as a dpc or cavity tray for edge details. It is sometimes more
difficult to form cavity trays at internal and external corners, at changes in
level, or at complex junctions; in such locations the use of preformed
components may be advisable.
It is also important that the radon-proof membrane is not damaged during
construction. This might be achieved by installing the membrane at a later
stage of construction, eg over the floor immediately before laying of the
screed (see Figure 10). If laid beneath the slab, the barrier may need to be
protected against damage when tamping of concrete takes place.
It is important to check that the barrier is not damaged in any way before it
is covered with concrete or other construction work. Damage should be
repaired before proceeding with later works. Any damaged part of the barrier
can be repaired by overlaying it with a piece of membrane material, held in
place by tape or sealant, to provide a minimum overlap of 150 mm.
With careful design and selection of material and good workmanship, a
single barrier will satisfy the requirements of both damp-proofing and
radon protection.
Radon protection to cavities
1
2
Cavity tray extending
150-200 mm across
floor beyond the
inner face of wall
External wall
and building
shell completed
making the
structure weathertight
Airbrick
Suspended
concrete floor
Weephole
Cavity filled
with concrete
to provide
support to
cavity tray
13
3
Floor topping and
insulation installed
over membrane
taped to cavity tray.
All work carried out
within weathertight
structure
Figure 10 Construction steps to minimise damage to barrier and enable sealing of barrier joints to be carried out in dry conditions
Radon protection to cavities
One of the routes by which radon might enter a building is by way of the wall
cavities (Figure 11), and therefore the radon-proof barrier should extend
across the cavity to prevent radon entry. Where the barrier crosses the cavity,
it will need to be constructed in the form of a cavity tray to prevent the ingress
of water from the outer to the inner leaf. The barrier should be continuous and
as airtight as possible; all joints, including any in the cavity tray, should be
carefully and durably sealed. As with all cavity trays, weepholes will have to
be provided in the outer leaf to drain the cavity. To ensure that the cavity tray
is fully supported, the cavity should be filled up to the barrier with concrete or
other suitable material.
Figure 11 Radon entry through unprotected wall cavities
Lapping and sealing of membranes and trays
When the membrane material is selected, consideration should be given to
jointing. Some materials are difficult to seal in adverse weather. Commonly
available materials include adhesive tapes and self-adhesive synthetic rubber
strip sealants. Both can prove effective if installed correctly, although the
latter is likely to offer greater confidence in achieving radon-proof joints.
Wherever the membrane or tray needs to be lapped and sealed, care must
be taken to ensure a very good standard of work. Attention to detail and good
workmanship is essential if the barrier is to be effective. It is important to
check that all joints have been correctly sealed prior to covering with later
construction. It should be borne in mind that radon is a gas, so it is necessary
to achieve as gas-tight a seal as possible between all parts of the barrier and to
seal penetrations such as service entries and exits.
14
Detailed protective measures
Continuity of barriers through internal walls
The radon-proof barrier should be continuous across the whole plan of the
building, including taking it through or under internal walls.
Where internal walls sit on top of a ground-bearing concrete slab, which in
some cases may have been thickened to provide additional support, the wall
should be built off the membrane or its covering in such a way as to leave the
membrane intact (Figure 12). Sometimes it will be convenient to build these
walls off a 600 mm wide strip of membrane material, and to lap and seal this to
the main membrane before screeding. (This will reduce the risk of damage
from traffic.)
Where internal walls are constructed with their own foundations, a strip of
membrane material which can be sealed to the main membrane will need to
be built-in. It may be convenient to achieve this by using a 600 mm wide strip
of membrane material which can be lapped and sealed to the main membrane
before screeding. The radon-proof barrier can double as a dpc within the wall.
Loadbearing wall
Light partition
600 mm strip of membrane under
wall with main membrane lapped
and sealed later
Figure 12 Avoidance of breaking the radon-proof barrier beneath internal walls
Continuity of barriers through party or separating walls
Semi-detached and terraced properties should be considered as single units
with regard to the installation of the radon-proof barrier. The barrier will need
to continue across party or separating walls where they occur.
Service penetrations
Tape
‘Top hat’
Radonproof
barrier
Figure 13 Achieving an airtight seal
around service penetrations
Where possible, service entries should avoid penetrating the radon-proof
membrane. Where this is not possible it will be necessary to construct an
airtight seal around each entry (Figure 13). Prefabricated ‘top hat’ sections are
available from some membrane manufacturers for sealing around pipe entries.
Penetrations should be avoided at points where the membrane is lapped,
because of the greater difficulty of resealing. With careful design all supply
services, with the exception of mains water and drainage to foul outlets, can
be brought up the outside of the building to enter through walls. However,
accommodating service entries in walls may limit where internal fixtures can
be placed. Traps and other services should be located so as not to damage the
radon-proof barrier within the floor slab.
Tanking to basements and cellars
If a basement or cellar is to be fully tanked using mastic asphalt or some
similarly impervious barrier to prevent damp penetration, the tanking will also
provide radon protection. There is no need to provide supplementary
protection (eg a sump) in such cases.
Slip or shear planes
15
Slip or shear planes
It is important to ensure that the inclusion of membranes with cavity trays
does not adversely affect the structural integrity of loadbearing walls. The
designer should consider avoiding having a cavity tray directly on top of a
membrane, or vice versa, within any loadbearing wall, as this can create a slip
or shear plane. This becomes more important where both of the materials
being used have shiny surfaces, like polyethylene. The risk is most severe if
the building may be subjected to lateral loading, as might be the case in
exposed locations. The risk is considered minimal for one- and two-storey
dwellings, but it is more significant with taller buildings.
In view of the expense of correcting deflected walls, avoidance of slip
planes in all construction is advised. One solution is to join the membrane to
the cavity tray over the floor instead of within the wall (Figure 10).
Blinding
Where a membrane is to be placed over fill, the fill should be blinded (ie its
surface finished with a fine material) to leave a smooth surface which will not
puncture the membrane. This is especially important if ordinary building
polyethylene is used, but care is required even with tougher reinforced
membrane materials. Care must be taken to ensure that the blinding material
does not block up the voids in the fill, or the efficiency of the depressurisation
system will be impaired. This is particularly important if the permeable fill is
of limited thickness. Foam sheeting could be used instead of blinding, but this
is likely to be more expensive.
Where the radon-proof membrane would otherwise be left exposed within
a ventilated space, it is advisable to cover it with a thin topping of concrete or
sand to reduce the risk of damage by following trades.
Reinforced slabs
Where an in-situ concrete slab is laid with its edge supported on the inner leaf
of an external wall, the slab must be strong enough to prevent cracking in the
centre of the slab should the fill beneath settle. Such slabs should be
reinforced.
Accessible thresholds
In addition to being provided with adequate radon protection, all new
dwellings should be provided with an accessible threshold to at least one
entrance, in accordance with the guidance in the 1999 edition of the
Approved Document[5] for Part M of the Building Regulations. All of the
solutions described in this report result in some difference in level between
the outdoor ground level and the indoor finished floor level. In all cases this is
due to the need to provide adequate damp protection. However, it is further
compounded with suspended floors where underfloor ventilation has to be
provided. In order to keep detailing of barriers within suspended floors
simple, the need for additional ramping to entrances may have to be accepted.
Alternatively the detail shown in Figure 14 could be adopted.
Condensation and cold bridges
Condensation and cold bridging are matters to be considered. For further
guidance see BRE Report Thermal insulation: avoiding risks.
16
Detailed protective measures
Cavity fill insulation
Cavity tray
for damp
protection
Floor topping
Insulation
Weephole
Radon barrier
in wall
75 mm
Radon barrier in
floor sealed to
radon barrier in wall
Suspended
concrete floor
Periscope air vent.
Joints in two-piece
vents should be taped
Cavity filled to
support radon
barrier through
wall
Figure 14 Suspended floor detail with reduced step at threshold
Subfloor ventilation
Where airbricks are recommended as the means of dispersing radon from
beneath beam-and-block floors, they should be installed where possible on all
sides of the building, and should be placed at intervals at least as frequent as
would be normal for an ordinary suspended timber floor (ie openings should
be large enough to give an actual opening of at least equivalent to 1500 mm2
for each metre run of wall on two opposite sides). Typically this means that
vents should be positioned at 2 m maximum centres along the external walls
and not more than 450 mm from corners. This may be contrary to the normal
practice of some builders in South-West England who tend to use fewer
airbricks because of the high winds experienced in the region. It is also
important to ensure that all airbricks are kept clear. Landscaping works such
as paths and driveways must not compromise subfloor ventilation.
Where periscope subfloor ventilators are used, the joints between the
upper and lower halves of the ventilators should be taped to reduce the risk of
radon entering the cavity. As it is difficult to seal a radon-proof barrier or
cavity tray to a periscope ventilator, it is important to try to locate ventilators
so that they do not penetrate the radon-proof barrier or cavity tray.
Subfloor depressurisation
Pipe taken through the
wall or up through the roof
Sump
Plan views
Figure 15 Central positioning of sump
under dwelling
Where a ground-supported floor is to be constructed and full radon
protection measures are required, a radon sump should be provided. This
would enable subfloor depressurisation to be introduced with relative ease if
desired at a later date. (Subfloor depressurisation involves sucking radonladen air from beneath a building and discharging it harmlessly into the
atmosphere.)
It should be noted that although this report refers to subfloor
depressurisation, in some cases, particularly where soils are highly
permeable, subfloor pressurisation can prove more effective; for further advice
contact BRE.
For a typical house a single sump will probably be sufficient. (Where clean
permeable fill has been used, a single sump is likely to have an influence over
an area of approximately 250 m2, or for a distance of 15 m from the sump.) If
the house is of modest size and of regular shape, an edge-located sump may
be acceptable. Otherwise the sump should be positioned centrally under the
house (Figure 15) and constructed to ensure that its pipe entry is not blocked
when the fill is placed. To allow for maximum depressurisation, fill used
beneath the slab should not contain excessive fines.
Sump construction
17
Sump construction
A simple sump can be constructed using bricks laid in a honeycomb bond so
as to form a box around the end of the pipe (Figure 16). To avoid subsequent
collapse when compacting fill around the sump, mortar should be used for
horizontal joints. However, it is essential that all perpends are left open.
Prefabricated sumps, usually of plastics construction (Figure 17), are widely
available and may be used as an alternative to brick construction.
Typically the pipe from the sump needs to be 110 mm diameter PVC-U
with joints using standard couplings which are sealed and airtight. The pipe
needs to leave the building so that it could be coupled to a fan mounted on the
external wall. It will therefore ideally need to terminate about 100 mm from
the external wall, and be located at the rear of the house or at a re-entrant
corner where subsequent installation of a boxed-in fan and vertical stack will
be least obtrusive. Until such time as a fan is installed, the pipe should be
capped off just above ground level to prevent vermin and rain penetration.
The pipe should be capped with an access plug (Figure 18); there is no
advantage to be gained by capping with a vent cowl.
Geotextile drainage matting can be laid beneath the slab (Figure 19) and
connected to an extract pipe to provide a sump. The matting is likely to prove
more expensive than a sump.
It should be noted that the sump and pipework are only installed as a
fallback measure and do not provide any radon removal until such time as a
fan is installed or until the sump is connected to a passive stack system.
Paving slab
Concrete
Polyethylene
sheet
Blinding
110 mm diameter
PVC-U pipe
Hardcore
Bricks laid in
honeycomb
bond. Perpends
must be left open
Ventilation
gaps
Bricks laid in honeycomb bond.
Perpends must be left open
Figure 16 Radon sump details
Access plug
Pipework
from sump
Figure 18 Pipework from sump capped-off with an access plug just
above ground level
Reinforced in-situ
concrete slab
Airflow
To fan
Radon-contaminated air
flows into the box and
to the fan
Figure 17 Prefabricated plastics sump
Radon barrier
Geotextile matting
Hardcore
Figure 19 Geotextile matting used as an alternative to a sump
18
Detailed protective measures
Edge-located sumps
In addition to the use of centrally located sumps, experience gained by BRE in
developing radon remedial measures for use in existing houses has led to the
development of externally excavated sump systems. Research has shown that
such systems can prove effective in reducing indoor radon levels within small
to medium-sized houses. This would suggest that although it is preferable to
locate a sump centrally within a new house, an edge-located mini-sump
would be adequate for small to medium-sized houses.
A simple edge-located mini-sump can be constructed by excavating a small
hole (about 400 × 400 × 400 mm) in the hardcore or fill beneath the dwelling
alongside the perimeter wall to form an open area around the end of the
extract pipe. The sump can be covered with a 600 × 600 mm paving slab or
similar to provide permanent formwork to support the floor slab. It is
important to ensure that the pipe is well sealed where it passes through the
wall (Figure 20). Prefabricated sumps or standard sumps can also be used as
edge-located sumps.
Permanent
formwork
Plate indicating location
of sump pipework below
In-situ
concrete slab
Access plug
Hardcore
Sump
Pipework from sump
sealed where it passes
through wall
Sump approximately
400 x 400 x 400 mm
Figure 20 Edge-located sump detail
Fan location
Figure 21 Pipework ducted internally,
with the fan outlet through the roof and not
ventilated into the roof space
Although installation of the fan is not required at the construction stage, its
location should be considered. The fan should be positioned with the outlet
well away from windows, doors and ventilation grilles, ideally discharging just
above eaves level. Low-level discharge may be possible if there are no
openings or vents close by. To avoid penetrating the radon-proof membrane
in the floor unnecessarily, the pipe should preferably be taken through the
wall, not up through the floor. However, it may be desired for aesthetic
reasons to locate pipework in ducts inside the house and to take the outlet
from the fan through the roof (Figure 21). It is not satisfactory for the fan to
ventilate into a roof space. Where pipework is ducted through the dwelling
and a fan is fitted, it should always be placed as close to the outlet as practical.
This is to ensure that the pipework is always under suction, as even slight
leaks could increase indoor radon concentrations. More detailed advice on
activating sump systems is contained in BRE Report Radon sump systems: a
BRE guide to radon remedial measures in existing dwellings.
Other points to consider with sumps
19
Other points to consider with sumps
It is important to label the capped-off extract pipe so that it can be located in
the future and its purpose made clear. A sign (of low visibility) fixed to an
adjacent wall would suffice. This should reduce the risk of accidental
connection to drainage fittings.
If the subfloor area comprises several compartments, then sumps may be
required for each compartment (Figure 22). These may be connected to a
manifold and a single fan (Figure 22 (a) and (b)). However, in most cases there
is no need to establish a manifold of pipes. A single sump located alongside
the separating wall, with a few bricks omitted or pieces of pipe located within
the wall to allow depressurisation, will suffice (Figure 22(c)). It is important for
fill to contain minimal fines in order not to impair the efficiency of the
depressurisation system.
Key
KeySump
Fan
Plan views
Plan view
(a) Pipework manifolded
to external fan
(b) Pipework manifolded
to internal fan
(c) Bricks omitted
in separating wall
Figure 22 Location of sumps within multi-compartment subfloor areas
Passive stack subfloor depressurisation
Subfloor depressurisation is usually achieved actively using an electric fan to
provide suction. However, it may be possible to depressurise the subfloor area
sufficiently without using a fan, ie passively. Such a system would comprise a
vertical stack pipe run up through the house from the radon sump to
discharge at a point at or above ridge level. Passive stack ventilation is best
suited to centrally located sumps. Further information is available in BRE
Good Building Guide 25.
High water-table
In areas where it is known that the water-table is particularly high, or the level
fluctuates, there is a risk that radon sumps may become waterlogged and
therefore ineffective. In such cases tanking should be used to prevent water
ingress and provide radon protection. There is then no need to provide a
radon sump. It should be noted that, generally, water will act as a screen to
radon. However, if the water level fluctuates, the ground pressure will also
change, which in turn may drive more radon into the building.
Garages
Integral garages with occupied rooms above, or with direct access through a
doorway from the garage to the house, need the same provision as the rest of
the dwelling.
Extensions
New extensions are subject to the Building Regulations unless they fall within
the exemptions listed in Class VII of Schedule 2 to the Regulations. However,
it is advisable that even an exempt extension has appropriate radon protection
measures incorporated if the extension is to be enclosed. For a house with
radon-protective measures the extension should include protective measures
20
Detailed protective measures
equivalent to those in the existing house. The radon-proof barrier to the
extension should be linked to the system of protection for the existing house.
Guidance on how this might be achieved can be found in BRE Good Building
Guide 25 (see Part 4: Protecting new extensions and conservatories). Where a
sump is necessary, experience has shown that for an extension of up to 30 m2
in ground-floor area an edge-located sump would be appropriate.
Landfill gas and radon
Although very rare, there may be cases where the dwelling being constructed
is located on or adjacent to a landfill site or old coalfield. In such cases
additional precautions may be needed to deal with methane. Appropriate
measures for dealing with methane are described in BRE Report Construction
of new buildings on gas-contaminated land. The measures described exceed
those required for radon, so where both methane and radon are present,
methane-protective measures should be applied, and only intrinsically safe
(non-sparking) fans and switchgear should be used.
Monitoring of completed houses
It is not a requirement of the Building Regulations for houses to be tested for
radon. If, however, a test is contemplated, then, in order to obtain the most
reliable results, houses should be monitored for a period of several months
when occupied using etchtrack (plastic) detectors. Ideally, monitoring should
be carried out during the winter; indoor radon concentrations are likely to be
at their highest at this time of year because of increased heating coupled with
a reduction in window opening. Ideally, houses should be monitored only
after they have been occupied for several months so that measurements are
not affected by windows being open for drying-out purposes.
Further information on monitoring is available in a DETR leaflet Radon: you
can test for it [6].
21
Stepped foundations:
additional points to
consider
Ventilation
space
Figure 23 Provision of a ventilated space
around a building built into the hillside
Where possible, stepped foundations should be avoided, as they complicate
the achievement of radon protection using only sealing techniques. It may
prove less expensive to excavate around the house (Figure 23) to provide a
ventilated space, than to try to build into the hillside and seal all the faces of
the building which are below ground level. Knowledge of how to construct
stepped foundations sealed against radon is limited, but the following points
should be considered.
● Where a suspended concrete floor is used, any space below it should be
ventilated to the outside.
● It is important that any radon-proof barrier should be incorporated in such
a way as not to create a slip plane. This is of particular importance for a
retaining wall. Similarly, continuity of any structural reinforcement will
need to be considered at points where it would penetrate the membrane.
Structural requirements remain of paramount importance.
● As with floors built on one level, it is important to try to avoid positioning
service entries where they would penetrate the radon-proof barrier. Where
they do penetrate the barrier they will need to be adequately sealed.
● It may be possible to use self-adhesive bitumen-coated polyethylene sheet
for the vertical radon-proof barrier. However, it may require some form of
additional restraint if it is not to suffer from wind damage during
construction. It would also be advisable to apply a render coat on nailed
lathing or a masonry skin over the membrane to ensure that it remains in
position once the building is complete. This is of particular importance
where storey-height areas of sheet material are being applied.
An alternative to this solution is to tank the basement area fully with
asphalt. This has been found to work successfully in the USA and provides
a robust solution to radon ingress.
Proprietary waterproofing systems and surface coating products
available for waterproofing purposes, such as liquid bitumen, cementitious
coatings, and plastic-based coatings, may be suitable for radon protection.
However, if they are to work they will need to be correctly applied.
● Subfloor depressurisation should be considered wherever a solid floor is
proposed. Similarly, in basement construction it will be necessary to
consider providing depressurisation to the areas of soil backfilled against
the external walls. Geotextile drainage matting could be used in place of
sumps. It could prove particularly useful for providing a vertical ventilation
space behind retaining walls. It may be possible for subsoil drain pipes from
these spaces to double up as radon extract pipes.
22
Acknowledgements
The guidance in this report draws upon the research and experience of
Building Research Establishment Ltd. Thanks go to the members of the
National Radiological Protection Board and the British Geological Survey for
their assistance in preparing this report, and to all those who provided
comment during the consultation stage.
Further information
● For further advice regarding building matters contact: BRE, Garston,
Watford, WD2 7JR; telephone 01923 664000.
● For further advice regarding radon measurement contact: Radon Survey,
National Radiological Protection Board, Chilton, Didcot, Oxon,
OX11 ORQ; telephone 01235 831600.
● For further advice regarding geological matters contact: British Geological
Survey, Keyworth, Nottingham, NG12 5GG; telephone 0115 936 3100.
References and further reading
[1] Department of the Environment and the Welsh Office. The Building Regulations 1991.
Statutory Instrument 1991 No 2768. London, HMSO, 1991.
[2] Department of the Environment and the Welsh Office. The Building Regulations 1991
Approved Document C. Site preparation and resistance to moisture. London, HMSO (1992
edition, as amended).
[3] Ionising Radiations Regulations 1985. Statutory Instrument 1985 No 1333. London, HMSO.
[4] Health and Safety at Work etc Act 1974.London, HMSO, 1974.
[5] Department of the Environment and the Welsh Office. The Building Regulations 1991
Approved Document M. Access and facilities for disabled people. London, The Stationery Office
(1999 edition). Also see supporting document:
Department of the Environment, Transport and the Regions. Accessible thresholds in new
housing: guidance for house builders and designers. London, The Stationery Office, 1999.
[6] Department of the Environment, Transport and the Regions. Radon: you can test
for it. Leaflet. Distributed by: DETR Free literature, PO Box 236, Wetherby, LS23 7NB.
Building Research Establishment
Reports
Construction of new buildings on gas-contaminated land. BR212, 1991.
Radon: guidance on protective measures for new dwellings in Scotland. (In preparation.)
Thermal insulation: avoiding risks. BR 262, 1994.
Scivyer C R and Gregory T J. Radon in the workplace. BR293, 1995.
BRE guides to radon remedial measures in existing dwellings
Pye P W. Sealing cracks in solid floors. BR239, 1993.
Scivyer C R. Surveying dwellings with high indoor radon levels. BR250, 1993.
Scivyer C R. Major alterations and conversions. BR267, 1994.
Scivyer C R, Cripps A and Jaggs M P R. Radon sump systems. BR227, 1998
(second edition).
Scivyer C R and Jaggs M P R. Dwellings with cellars and basements. BR343, 1998.
Stephen R K. Positive pressurisation. BR281, 1995.
Welsh P A, Pye P W and Scivyer C R. Protecting dwellings with suspended timber floors.
BR270, 1994.
BRE publications are available from:
CRC Ltd
151 Rosebery Avenue
London, EC1R 4GB
tel: 0171 505 6622
fax: 0171 505 6606
Good Building Guides
GBG25 Buildings and radon
GBG26 Minimising noise from domestic fan systems and fan-assisted radon mitigation systems
Video
Radon, no problem. 1994.
Annex A
Maps of areas where basic or full
protection should be provided
Annex A: Maps of areas where basic or full protection should be provided
NT
NU
NY
NZ
SD
SE
TA
SH
SJ
SK
TF
TG
SM
SN
SO
SP
TL
TM
SR
SS
ST
SU
TQ
TR
SW
SX
SY
SZ
TV
NX
HWRC_SDST
25
CL_LMST
© Crown copyright. All rights reserved
Annex A - Map 1
Areas where Basic or Full protection should be provided
See also Annex B (Map 2 and Plates 12-22)
This map is based upon the OS map by DETR with the
permission of Ordnance Survey on behalf of The Controller of
Her Majesty's Stationery Office. Unauthorised reproduction
infringes Crown Copyright and may lead to prosecution or civil
proceedings.
Licence Number: GD272671
26
Annex A: Maps of areas where basic or full protection should be provided
1
2
Milford Haven
Pembroke Dock
0
Pontarddulais
Llanelli
Tenby
Clydach
Swansea
9
Port Eynon
8
7
6
SR
5
SS
4
Barnstaple
3
Bideford
2
1
1
Bude
0
Okehampton
9
8
Tavistock
Wadebridge
7
Liskeard
6
Plymouth
St Austell
SW
5
SX
Truro
Camborne
4
Penzance
3
Helston
2
1
2
3
4
5
6
7
8
9
2
0
1
2
3
4
5
6
7
© Crown copyright. All rights reserved
PLATE 1 Cornwall and west Devon
Areas where Basic or Full protection should be provided
See also Annex B (Plate 12)
This map is based upon the OS map by DETR with the
permission of Ordnance Survey on behalf of The Controller
of Her Majesty's Stationery Office. Unauthorised reproduction
infringes Crown Copyright and may lead to prosecution or
civil proceedings.
Licence Number: GD272671
27
Annex A: Maps of areas where basic or full protection should be provided
3
Brecon
Sennybridge
Llandeilo
Cheltenham
2
Gloucester
Crickhowell
Abergavenny
Monmouth
Coleford
Ystradglynais
1
Merthyr Tydfil
Hirwaun
Pontarddulais
2
0
Llanelli
Blaenavon
Ebbw Vale
Abertillery
Pontardawe
Aberdare
Clydach
Stroud
Usk
Pontypool
Neath
Swansea
Port Talbot
9
Blackwood
Porth
Cwmbran
Chepstow
Pontypridd
Ogmore Vale
Maesteg
Magor
Newport
Thornbury
Caerphilly
Bridgend
Porthcawl
8
Cardiff
7
Chippenham
Bristol
Cowbridge
Barry
Bath
Weston Super Mare
6
Trowbridge
Midsomer Norton
ST
5
Minehead
4
Shepton Mallet
Bridgwater
Barnstaple
3
Taunton
2
Yeovil
Tiverton
1
1
Blandford Forum
0
Okehampton
Exeter
Dorchester
9
Sidmouth
Wareham
8
Weymouth
Newton Abbot
7
Torquay
Totnes
6
SY
5
4
Salcombe
3
5
6
7
8
9
3
0
1
2
3
4
5
6
7
8
9
4
0
© Crown copyright. All rights reserved
PLATE 2 Bristol, east Devon, Somerset and South Wales
Areas where Basic or Full protection should be provided
See also Annex B (Plate 13)
This map is based upon the OS map by DETR with the
permission of Ordnance Survey on behalf of The Controller
of Her Majesty's Stationery Office. Unauthorised reproduction
infringes Crown Copyright and may lead to prosecution or
civil proceedings.
Licence Number: GD272671
28
Annex A: Maps of areas where basic or full protection should be provided
6
Worcester
Stratford upon Avon
5
SP
Pershore
4
Bedford
Towcester
Biggleswade
Banbury
3
Milton Keynes
Letchworth
Tewkesbury
Stevenage
Cheltenham
Luton
2
Gloucester
Aylesbury
Witney
1
2
St Albans
Oxford
Stroud
Cirencester
0
Amersham
Abingdon
High Wycombe
Wallingford
9
Wembley
Swindon
Uxbridge
Ealing
8
Windsor
Chippenham
Reading
7
Teddington
Bracknell
Staines
Newbury
Esher
Devizes
6
Camberley
Woking
Epsom
Trowbridge
SU
5
Basingstoke
Fleet
Dorking
Guildford
Redhill
4
Crawley
Horsham
Salisbury
3
Winchester
Petersfield
Romsey
Eastleigh
2
Southampton
1
Lyndhurst
Blandford Forum
Havant
Chichester
Fareham
Littlehampton
Wimborne
1
Worthing
0
Portsmouth
Christchurch
Poole
9
Newport
Wareham
8
Ventnor
7
6
8
9
4
0
1
2
3
4
5
6
7
8
9
5
0
1
2
3
© Crown copyright. All rights reserved
PLATE 3 Southampton and the South
Areas where Basic or Full protection shoul be provided
See also Annex B (Plate 14)
This map is based upon the OS map by DETR with the
permission of Ordnance Survey on behalf of The Controller
of Her Majesty's Stationery Office. Unauthorised reproduction
infringes Crown Copyright and may lead to prosecution or
civil proceedings.
Licence Number: GD272671
Annex A: Maps of areas where basic or full protection should be provided
29
9
Ely
8
Mildenhall
Huntingdon
7
Bury St Edmunds
6
Stowmarket
Cambridge
TL
5
Biggleswade
TM
Woodbridge
Ipswich
Hadleigh
4
Saffron Walden
Letchworth
3
Colchester
Stevenage
Braintree
2
Hertford
1
Maldon
Chelmsford
Cheshunt
2
Clacton On Sea
Harlow
St Albans
Epping
0
Enfield
Brentwood
9
Basildon
Dagenham
Southend On Sea
Wembley
London
Ealing
8
Woolwich
Dartford Gravesend
Teddington
7
Bromley
Croydon
Esher
6
Margate
Chatham
Sittingbourne
Epsom
Canterbury
Maidstone
Sevenoaks
Oxted
5
TR
TQ
Redhill
Dorking
Ashford
Dover
Royal Tunbridge Wells
4
Crawley
Folkestone
Horsham
3
Haywards Heath
2
Battle
Hailsham
1
Hastings
Brighton
Worthing
1
Newhaven
0
9
Eastbourne
1
2
3
4
5
6
7
8
9
6
0
1
2
3
4
5
6
© Crown copyright. All rights reserved
PLATE 4 London and the Southeast
Areas where Basic or Full protection should be provided
See also Annex B (Plate 15)
This map is based upon the OS map by DETR with the
permission of Ordnance Survey on behalf of The Controller
of Her Majesty's Stationery Office. Unauthorised reproduction
infringes Crown Copyright and may lead to prosecution or
civil proceedings.
Licence Number: GD272671
Annex A: Maps of areas where basic or full protection should be provided
30
4
0
Amlwch
9
Holyhead
8
Rhyl
CL_LMST
Beaumaris
Llangefni
Menai Bridge
Bangor
7
Colwyn
Conwy
Bay
Llanfairfechan
St. Asaph
Denbigh
Bethesda
Llanrwst
Caernarfon
6
Betws-y-coed
SH
5
Blaenau Ffestiniog
Corwen
4
Penrhyndeudraeth
Criccieth
Nefyn
Pwllheli
Bala
Trawsfynydd
Porthmadog
Harlech
3
2
Dolgellau
Barmouth
Mallwyd
1
3
Tywyn
0
Machynlleth
Aberdovey
Carno
9
Llanidloes
Aberystwyth
8
Llangurig
Ponterwyd
7
Rhayader
Llandrindod Wells
Aberaeron
6
Tregaron
New Quay
SM
5
SN
Cardigan
Builth Wells
Lampeter
Llanwrtyd Wells
Llandyssul
4
Newcastle Emlyn
Llandovery
Fishguard
3
St. Davids
Sennybridge
Brecon
Llandeilo
Carmarthen
2
Whitland
Haverfordwest
Narberth
1
2
0
Ystradglynais
Merthyr Tydfil
Hirwaun
Milford Haven
Pembroke Dock
6
7
8
9
2
0
Pontarddulais
Llanelli
Tenby
1
2
3
4
5
Clydach
6
7
Pontardawe
Aberdare
8
9
3
0
1
© Crown copyright. All rights reserved
PLATE 5 West and North Wales
Areas where Basic or Full protection should be provided
See also Annex B (Plate 16)
This map is based upon the OS map by DETR with the
permission of Ordnance Survey on behalf of The Controller
of Her Majesty's Stationery Office. Unauthorised reproduction
infringes Crown Copyright and may lead to prosecution or
civil proceedings.
Licence Number: GD272671
Annex A: Maps of areas where basic or full protection should be provided
1
Bolton
Barnsley
Oldham
Ormskirk
31
Wigan
4
0
St Helens
Manchester
Rotherham
Liverpool
9
Stockport
Warrington
Widnes
Sheffield
Rhyl
8
St. Asaph
Macclesfield
Holywell
Buxton
Ellesmere Port
Chesterfield
Flint
7
Connah’s Quay
Denbigh
Bolsover
Winsford
Chester
Mold
Matlock
6
Ruthin
Coedpoeth
5
SJ
Wrexham
Leek
Crewe
SK
Newcastle
Corwen
Ripley
Llangollen
4
Ilkeston
Derby
3
Wem
Oswestry
Burton Upon Trent
Stafford
Llanrhaeadr-ym-Mochnant
2
Coalville
Shrewsbury
1
Telford
Welshpool
Cannock
Lichfield
Llanfair Caereinion
3
0
Tamworth
Montgomery
Atherstone
Wolverhampton
Hinckley
Bridgnorth
Newtown
Nuneaton
9
Dudley
Birmingham
Coventry
8
Knighton
7
Solihull
Kidderminster
Ludlow
Bromsgrove Redditch
Royal Leamington Spa
Llandrindod Wells
6
Leominster
Worcester
Stratford upon Avon
SO
Builth Wells
5
SP
Malvern
Pershore
Hay-on-Wye
4
3
Banbury
Hereford
Bronllys
Tewkesbury
Brecon
Cheltenham
2
Crickhowell
Gloucester
Abergavenny
Monmouth
Coleford
1
3
0
1
2
3
4
5
6
Witney
7
8
9
4
0
1
2
3
4
5
© Crown copyright. All rights reserved
PLATE 6 Welsh Border and the West Midlands
Areas where Basic or Full protection should be provided
See also Annex B (Plate 17)
This map is based upon the OS map by DETR with the
permission of Ordnance Survey on behalf of The Controller
of Her Majesty's Stationery Office. Unauthorised reproduction
infringes Crown Copyright and may lead to prosecution or
civil proceedings.
Licence Number: GD272671
Annex A: Maps of areas where basic or full protection should be provided
32
2
Huddersfield
Scunthorpe
1
Barnsley
Grimsby
Brigg
Doncaster
4
0
Rotherham
Gainsborough
9
Louth
Sheffield
8
Worksop
Buxton
Chesterfield
Lincoln
7
Bolsover
Mansfield
Matlock
6
Newark
SK
Ripley
5
Boston
Nottingham
Ilkeston
4
Sleaford
Grantham
Derby
3
Burton Upon Trent
Spalding
2
Loughborough
Coalville
1
Lichfield
Oakham
Leicester
Tamworth
3
0
March
Narborough
Atherstone
Peterborough
Hinckley
Nuneaton
9
Birmingham
Solihull
8
Coventry
Kettering
Thrapston
Rugby
Huntingdon
7
Redditch
Wellingborough
Royal Leamington Spa
Daventry
Northampton
6
Cambridge
Stratford upon Avon
SP
5
4
Bedford
Towcester
Biggleswade
Banbury
Milton Keynes
Letchworth
3
Stevenage
Luton
2
4
0
1
2
3
4
5
6
7
8
9
5
0
1
2
3
4
5
© Crown copyright. All rights reserved
PLATE 7 East Midlands
Areas where Basic or Full protection should be provided
See also Annex B (Plate 18)
This map is based upon the OS map by DETR with the
permission of Ordnance Survey on behalf of The Controller
of Her Majesty's Stationery Office. Unauthorised reproduction
infringes Crown Copyright and may lead to prosecution or
civil proceedings.
Licence Number: GD272671
Annex A: Maps of areas where basic or full protection should be provided
33
3
2
TA
1
4
Grimsby
0
9
Louth
8
7
6
5
Boston
TF
TG
Cromer
4
3
Spalding
2
Kings Lynn
East Dereham
1
Great Yarmouth
Norwich
3
0
March
Lowestoft
Long Stratton
9
Ely
8
Mildenhall
Huntingdon
7
TL
6
TM
Bury St Edmunds
Stowmarket
Cambridge
5
Woodbridge
Hadleigh
Ipswich
4
Saffron Walden
Letchworth
3
2
3
4
5
6
7
8
9
6
0
1
2
3
4
5
6
7
© Crown copyright. All rights reserved
PLATE 8 East Anglia
Areas where a Basic or Full protection should be provided
See also Annex B (Plate 19)
This map is based upon the OS map by DETR with the
permission of Ordnance Survey on behalf of The Controller
of Her Majesty's Stationery Office. Unauthorised reproduction
infringes Crown Copyright and may lead to prosecution or
civil proceedings.
Licence Number: GD272671
Annex A: Maps of areas where basic or full protection should be provided
34
8
7
Newcastle
upon Tyne
Hexham
6
Carlisle
Consett
Chester Le Street
NY
5
Durham
4
Crook
Spennymoor
Penrith
3
Workington
2
Whitehaven
Barnard Castle
Darlington
1
5
Richmond
0
Kendal
9
8
7
Barrow In Furness
Morecambe
6
Skipton
SD
5
Clitheroe
4
Nelson
Blackpool
3
Bradford
Burnley
Preston
Lytham St Annes
Accrington
Halifax
Leyland
2
Huddersfield
Chorley
Bury
1
Rochdale
Bolton
Oldham
Ormskirk
Wigan
4
0
St Helens
Manchester
Liverpool
9
Stockport
Warrington
Widnes
Rhyl
8
8
9
3
0
1
2
3
4
5
6
7
8
9
4
0
1
2
3
© Crown copyright. All rights reserved
PLATE 9 Manchester, Merseyside and the Northwest
Areas where Basic or Full protection should be provided
See also Annex B (Plate 20)
This map is based upon the OS map by DETR with the
permission of Ordnance Survey on behalf of The Controller
of Her Majesty's Stationery Office. Unauthorised reproduction
infringes Crown Copyright and may lead to prosecution or
civil proceedings.
Licence Number: GD272671
35
Annex A: Maps of areas where basic or full protection should be provided
9
Morpeth
8
Whitley Bay
7
Newcastle upon Tyne
6
Sunderland
Consett
5
NZ
Chester Le Street
Durham
Easington
4
Crook
Spennymoor
Hartlepool
3
2
Middlesbrough
Barnard Castle
Darlington
1
5
Richmond
0
Northallerton
9
Scarborough
8
Malton
7
Bridlington
6
Harrogate
York
SE
5
TA
4
Leeds
Bradford
Selby
Hull
3
Goole
Wakefield
2
Huddersfield
Scunthorpe
1
Barnsley
Grimsby
Brigg
Doncaster
4
0
Rotherham
9
4
0
1
2
3
4
5
6
7
8
9
5
0
1
2
3
4
5
© Crown copyright. All rights reserved
PLATE 10 Teeside, Humberside and Yorkshire
Areas where Basic or Full protection should be provided
See also Annex B (Plate 21)
This map is based upon the OS map by DETR with the
permission of Ordnance Survey on behalf of The Controller
of Her Majesty's Stationery Office. Unauthorised reproduction
infringes Crown Copyright and may lead to prosecution or
civil proceedings.
Licence Number: GD272671
Annex A: Maps of areas where basic or full protection should be provided
36
7
6
Berwick Upon Tweed
NT
5
NU
4
3
2
Alnwick
1
6
0
9
Morpeth
8
Whitley Bay
7
Newcastle upon Tyne
Hexham
6
Carlisle
Sunderland
Consett
NY
5
NZ
Chester Le Street
Durham
Easington
4
Crook
Spennymoor
Penrith
3
2
Hartlepool
Middlesbrough
Barnard Castle
Darlington
1
5
Richmond
0
Northallerton
Kendal
9
8
7
2
3
4
5
6
7
8
9
4
0
1
2
3
4
5
6
7
© Crown copyright. All rights reserved
PLATE 11 Tyneside and the Northeast
Areas where Basic or Full protection should be provided
See also Annex B (Plate 22)
This map is based upon the OS map by DETR with the
permission of Ordnance Survey on behalf of The Controller
of Her Majesty's Stationery Office. Unauthorised reproduction
infringes Crown Copyright and may lead to prosecution or
civil proceedings.
Licence Number: GD272671
Annex B
Maps of areas where a
geological assessment should
be carried out
Annex B: Maps of areas where a geological assessment should be carried out
NT
NU
NY
NZ
SD
SE
TA
SH
SJ
SK
TF
TG
SM
SN
SO
SP
TL
TM
SR
SS
ST
SU
TQ
TR
SW
SX
SY
SZ
TV
NX
HWRC_SDST
39
CL_LMST
Annex B - Map 2
Areas where a Geological Assessment should be carried out
See also Annex A (Map 1 and Plates 1-11)
© Crown copyright. All rights reserved
This map is based upon the OS map by DETR with the
permission of Ordnance Survey on behalf of The Controller of
Her Majesty's Stationery Office. Unauthorised reproduction
infringes Crown Copyright and may lead to prosecution or civil
proceedings.
Licence Number: GD272671
Annex B: Maps of areas where a geological assessment should be carried out
40
1
2
Milford Haven
Pembroke Dock
0
Pontarddulais
Llanelli
Tenby
Clydach
Swansea
9
Port Eynon
8
7
6
SR
5
SS
4
Barnstaple
3
Bideford
2
1
1
Bude
0
Okehampton
9
8
Tavistock
Wadebridge
7
Liskeard
6
Plymouth
St Austell
SW
5
SX
Truro
Camborne
4
Penzance
3
Helston
2
1
2
3
4
5
6
7
8
9
2
0
1
2
3
4
5
6
7
© Crown copyright. All rights reserved
PLATE 12 Cornwall and west Devon
Areas where a Geological Assessment should be carried out
See also Annex A (Plate 1)
This map is based upon the OS map by DETR with the
permission of Ordnance Survey on behalf of The Controller
of Her Majesty's Stationery Office. Unauthorised reproduction
infringes Crown Copyright and may lead to prosecution or
civil proceedings.
Licence Number: GD272671
Annex B: Maps of areas where a geological assessment should be carried out
3
Brecon
Sennybridge
Llandeilo
Cheltenham
2
Gloucester
Crickhowell
Abergavenny
Monmouth
Coleford
Ystradglynais
1
2
0
Llanelli
Blaenavon
Merthyr Tydfil
Hirwaun
Pontarddulais
41
Ebbw Vale
Abertillery
Pontardawe
Aberdare
Clydach
Stroud
Usk
Pontypool
Neath
Swansea
Port Talbot
9
Blackwood
Porth
Cwmbran
Chepstow
Pontypridd
Ogmore Vale
Maesteg
Magor
Newport
Thornbury
Caerphilly
Bridgend
Porthcawl
8
Cardiff
7
Chippenham
Bristol
Cowbridge
Barry
Bath
Weston Super Mare
6
Trowbridge
Midsomer Norton
ST
5
Shepton Mallet
Minehead
4
Bridgwater
Barnstaple
3
Taunton
2
Yeovil
Tiverton
1
1
Blandford Forum
0
Okehampton
Exeter
Dorchester
9
Sidmouth
Wareham
8
Weymouth
Newton Abbot
7
Torquay
Totnes
6
SY
5
4
Salcombe
3
5
6
7
8
9
3
0
1
2
3
4
5
6
7
8
9
4
0
© Crown copyright. All rights reserved
PLATE 13 Bristol, east Devon, Somerset and South Wales
Areas where a Geological Assessment should be carried out
See also Annex A (Plate 2)
This map is based upon the OS map by DETR with the
permission of Ordnance Survey on behalf of The Controller
of Her Majesty's Stationery Office. Unauthorised reproduction
infringes Crown Copyright and may lead to prosecution or
civil proceedings.
Licence Number: GD272671
Annex B: Maps of areas where a geological assessment should be carried out
42
6
Worcester
Stratford upon Avon
5
SP
Pershore
4
Bedford
Towcester
Biggleswade
Banbury
3
Milton Keynes
Letchworth
Tewkesbury
Stevenage
Cheltenham
Luton
2
Gloucester
Aylesbury
Witney
1
2
St Albans
Oxford
Stroud
Cirencester
0
Amersham
Abingdon
High Wycombe
Wallingford
9
Wembley
Swindon
Uxbridge
Ealing
8
Windsor
Chippenham
Reading
7
Teddington
Bracknell
Staines
Newbury
Esher
Devizes
6
Camberley
Woking
Epsom
Trowbridge
SU
5
Basingstoke
Fleet
Dorking
Guildford
Redhill
4
Crawley
Horsham
Salisbury
3
Winchester
Petersfield
Romsey
Eastleigh
2
Southampton
1
Lyndhurst
Blandford Forum
Havant
Chichester
Fareham
Littlehampton
Wimborne
1
Worthing
0
Portsmouth
Christchurch
Poole
9
Newport
Wareham
8
Ventnor
7
6
8
9
4
0
1
2
3
4
5
6
7
8
9
5
0
1
2
3
© Crown copyright. All rights reserved
PLATE 14 Southampton and the South
Areas where a Geological Assessment should be carried out
See also Annex A (Plate 3)
This map is based upon the OS map by DETR with the
permission of Ordnance Survey on behalf of The Controller
of Her Majesty's Stationery Office. Unauthorised reproduction
infringes Crown Copyright and may lead to prosecution or
civil proceedings.
Licence Number: GD272671
Annex B: Maps of areas where a geological assessment should be carried out
43
9
Ely
8
Mildenhall
Huntingdon
7
Bury St Edmunds
6
Stowmarket
Cambridge
TL
5
Biggleswade
TM
Woodbridge
Ipswich
Hadleigh
4
Saffron Walden
Letchworth
3
Colchester
Stevenage
Braintree
2
Hertford
1
Maldon
Chelmsford
Cheshunt
2
Clacton On Sea
Harlow
St Albans
Epping
0
Enfield
Brentwood
9
Basildon
Dagenham
Southend On Sea
Wembley
London
Ealing
8
Woolwich
Dartford Gravesend
Teddington
7
Bromley
Croydon
Esher
6
Margate
Chatham
Sittingbourne
Epsom
Canterbury
Maidstone
Sevenoaks
Oxted
5
TR
TQ
Redhill
Dorking
Ashford
Dover
Royal Tunbridge Wells
4
Crawley
Folkestone
Horsham
3
Haywards Heath
2
Battle
Hailsham
1
Hastings
Brighton
Worthing
1
Newhaven
0
9
Eastbourne
1
2
3
4
5
6
7
8
9
6
0
1
2
3
4
5
6
© Crown copyright. All rights reserved
PLATE 15 London and the Southeast
Areas where a Geological Assessment should be carried out
See also Annex A (Plate 4)
This map is based upon the OS map by DETR with the
permission of Ordnance Survey on behalf of The Controller
of Her Majesty's Stationery Office. Unauthorised reproduction
infringes Crown Copyright and may lead to prosecution or
civil proceedings.
Licence Number: GD272671
44
Annex B: Maps of areas where a geological assessment should be carried out
4
0
Amlwch
9
Holyhead
8
Rhyl
CL_LMST
Beaumaris
Llangefni
Menai Bridge
Bangor
7
Colwyn
Conwy
Bay
Llanfairfechan
St. Asaph
Denbigh
Bethesda
Llanrwst
Caernarfon
6
Betws-y-coed
SH
5
Blaenau Ffestiniog
Corwen
4
Penrhyndeudraeth
Criccieth
Nefyn
Pwllheli
Bala
Trawsfynydd
Porthmadog
Harlech
3
2
Dolgellau
Barmouth
Mallwyd
1
3
Tywyn
0
Machynlleth
Aberdovey
Carno
9
Llanidloes
Aberystwyth
8
Llangurig
Ponterwyd
7
Rhayader
Llandrindod Wells
Aberaeron
6
Tregaron
New Quay
SM
5
SN
Cardigan
Builth Wells
Lampeter
Llanwrtyd Wells
Llandyssul
4
Newcastle Emlyn
Llandovery
Fishguard
3
St. Davids
Sennybridge
Brecon
Llandeilo
Carmarthen
2
Whitland
Haverfordwest
Narberth
1
2
0
Ystradglynais
Merthyr Tydfil
Hirwaun
Milford Haven
Pembroke Dock
6
7
8
9
2
0
Pontarddulais
Llanelli
Tenby
1
2
3
4
5
Clydach
6
Pontardawe
7
Aberdare
8
9
3
0
1
© Crown copyright. All rights reserved
PLATE 16 West and North Wales
Areas where a Geological Assessment should be carried out
See also Annex A (Plate 5)
This map is based upon the OS map by DETR with the
permission of Ordnance Survey on behalf of The Controller
of Her Majesty's Stationery Office. Unauthorised reproduction
infringes Crown Copyright and may lead to prosecution or
civil proceedings.
Licence Number: GD272671
Annex B: Maps of areas where a geological assessment should be carried out
1
Bolton
Barnsley
Oldham
Ormskirk
45
Wigan
4
0
St Helens
Manchester
Rotherham
Liverpool
9
Stockport
Warrington
Widnes
Sheffield
Rhyl
8
St. Asaph
Macclesfield
Holywell
Buxton
Ellesmere Port
Chesterfield
Flint
7
Connah’s Quay
Denbigh
Bolsover
Winsford
Chester
Mold
Matlock
6
Ruthin
Coedpoeth
5
SJ
Wrexham
Leek
Crewe
SK
Newcastle
Corwen
Ripley
Llangollen
4
Ilkeston
Derby
3
Wem
Oswestry
Burton Upon Trent
Stafford
Llanrhaeadr-ym-Mochnant
2
Coalville
Shrewsbury
1
Telford
Welshpool
Cannock
Lichfield
Llanfair Caereinion
3
Tamworth
0
Montgomery
Atherstone
Wolverhampton
Hinckley
Bridgnorth
Newtown
Nuneaton
9
Dudley
Birmingham
Coventry
8
Knighton
7
Solihull
Kidderminster
Ludlow
Bromsgrove Redditch
Royal Leamington Spa
Llandrindod Wells
6
Leominster
Worcester
Stratford upon Avon
SO
Builth Wells
5
SP
Malvern
Pershore
Hay-on-Wye
4
3
Banbury
Hereford
Bronllys
Tewkesbury
Brecon
Cheltenham
2
Crickhowell
Gloucester
Abergavenny
Monmouth
Coleford
1
3
0
1
2
3
4
5
6
Witney
7
8
9
4
0
1
2
3
4
5
© Crown copyright. All rights reserved
PLATE 17 Welsh Border and the West Midlands
Areas where a Geological Assessment should be carried out
See also Annex A (Plate 6)
This map is based upon the OS map by DETR with the
permission of Ordnance Survey on behalf of The Controller
of Her Majesty's Stationery Office. Unauthorised reproduction
infringes Crown Copyright and may lead to prosecution or
civil proceedings.
Licence Number: GD272671
Annex B: Maps of areas where a geological assessment should be carried out
46
2
Huddersfield
Scunthorpe
1
Barnsley
Grimsby
Brigg
Doncaster
4
0
Rotherham
Gainsborough
9
Louth
Sheffield
8
Worksop
Buxton
Chesterfield
Lincoln
7
Bolsover
Mansfield
Matlock
6
Newark
SK
Ripley
5
Boston
Nottingham
Ilkeston
4
Sleaford
Grantham
Derby
3
Burton Upon Trent
Spalding
2
Loughborough
Coalville
1
Lichfield
Oakham
Leicester
Tamworth
3
0
March
Narborough
Atherstone
Peterborough
Hinckley
Nuneaton
9
Birmingham
Solihull
8
Coventry
Kettering
Thrapston
Rugby
Huntingdon
7
Redditch
Wellingborough
Royal Leamington Spa
Daventry
Northampton
6
Cambridge
Stratford upon Avon
SP
5
4
Bedford
Towcester
Biggleswade
Banbury
Milton Keynes
Letchworth
3
Stevenage
Luton
2
4
0
1
2
3
4
5
6
7
8
9
5
0
1
2
3
4
5
© Crown copyright. All rights reserved
PLATE 18 East Midlands
Areas where a Geological Assessment should be carried out
See also Annex A (Plate 7)
This map is based upon the OS map by DETR with the
permission of Ordnance Survey on behalf of The Controller
of Her Majesty's Stationery Office. Unauthorised reproduction
infringes Crown Copyright and may lead to prosecution or
civil proceedings.
Licence Number: GD272671
Annex B: Maps of areas where a geological assessment should be carried out
47
3
2
TA
1
4
Grimsby
0
9
Louth
8
7
6
5
Boston
TF
TG
Cromer
4
3
Spalding
2
Kings Lynn
East Dereham
1
Great Yarmouth
Norwich
3
0
March
Lowestoft
Long Stratton
9
Ely
8
Mildenhall
Huntingdon
7
TL
6
TM
Bury St Edmunds
Stowmarket
Cambridge
5
Woodbridge
Hadleigh
Ipswich
4
Saffron Walden
Letchworth
3
2
3
4
5
6
7
8
9
6
0
1
2
3
4
5
6
7
© Crown copyright. All rights reserved
PLATE 19 East Anglia
Areas where a Geological Assessment should be carried out
See also Annex A (Plate 8)
This map is based upon the OS map by DETR with the
permission of Ordnance Survey on behalf of The Controller
of Her Majesty's Stationery Office. Unauthorised reproduction
infringes Crown Copyright and may lead to prosecution or
civil proceedings.
Licence Number: GD272671
48
Annex B: Maps of areas where a geological assessment should be carried out
8
7
Newcastle
upon Tyne
Hexham
6
Carlisle
Consett
Chester Le Street
NY
5
Durham
4
Crook
Spennymoor
Penrith
3
Workington
2
Whitehaven
Barnard Castle
Darlington
1
5
Richmond
0
Kendal
9
8
7
Barrow In Furness
Morecambe
6
Skipton
SD
5
Clitheroe
4
Nelson
Blackpool
3
Bradford
Burnley
Preston
Lytham St Annes
Accrington
Halifax
Leyland
2
Huddersfield
Chorley
Bury
1
Rochdale
Bolton
Oldham
Ormskirk
Wigan
4
0
Manchester
St Helens
Liverpool
9
Stockport
Warrington
Widnes
Rhyl
8
8
9
3
0
1
2
3
4
5
6
7
8
9
4
0
1
2
3
© Crown copyright. All rights reserved
PLATE 20 Manchester, Merseyside and the Northwest
Areas where a Geological Assessment should be carried out
See also Annex A (Plate 9)
This map is based upon the OS map by DETR with the
permission of Ordnance Survey on behalf of The Controller
of Her Majesty's Stationery Office. Unauthorised reproduction
infringes Crown Copyright and may lead to prosecution or
civil proceedings.
Licence Number: GD272671
Annex B: Maps of areas where a geological assessment should be carried out
49
9
Morpeth
8
Whitley Bay
7
Newcastle upon Tyne
6
Sunderland
Consett
5
NZ
Chester Le Street
Durham
Easington
4
Crook
Spennymoor
Hartlepool
3
2
Middlesbrough
Barnard Castle
Darlington
1
5
Richmond
0
Northallerton
9
Scarborough
8
Malton
7
Bridlington
6
Harrogate
York
SE
5
TA
4
Leeds
Bradford
Selby
Hull
3
Goole
Wakefield
2
Huddersfield
Scunthorpe
1
Barnsley
Grimsby
Brigg
Doncaster
4
0
Rotherham
9
4
0
1
2
3
4
5
6
7
8
9
5
0
1
2
3
4
5
© Crown copyright. All rights reserved
PLATE 21 Teeside, Humberside and Yorkshire
Areas where a Geological Assessment should be carried out
See also Annex A (Plate 10)
This map is based upon the OS map by DETR with the
permission of Ordnance Survey on behalf of The Controller
of Her Majesty's Stationery Office. Unauthorised reproduction
infringes Crown Copyright and may lead to prosecution or
civil proceedings.
Licence Number: GD272671
Annex B: Maps of areas where a geological assessment should be carried out
50
7
6
Berwick Upon Tweed
NT
5
NU
4
3
2
Alnwick
1
6
0
9
Morpeth
8
Whitley Bay
7
Newcastle upon Tyne
Hexham
6
Carlisle
Sunderland
Consett
NY
5
NZ
Chester Le Street
Durham
Easington
4
Crook
Spennymoor
Penrith
3
2
Hartlepool
Middlesbrough
Barnard Castle
Darlington
1
5
Richmond
0
Northallerton
Kendal
9
8
7
2
3
4
5
6
7
8
9
4
0
1
2
3
4
5
6
7
© Crown copyright. All rights reserved
PLATE 22 Tyneside and the Northeast
Areas where a Geological Assessment should be carried out
See also Annex A (Plate 11)
This map is based upon the OS map by DETR with the
permission of Ordnance Survey on behalf of The Controller
of Her Majesty's Stationery Office. Unauthorised reproduction
infringes Crown Copyright and may lead to prosecution or
civil proceedings.
Licence Number: GD272671