ENGINEERS IRELAND 5th November 2013
Monitoring the Remediation Works on Site
Paul Forde BE CEng MIStructE EurIng FIEI FConsEI
1. Remedial Works Plan
− This will have been prepared as part of the Tender Documents
and all of the headings below will have been
referenced/outlined.
Monitoring the Remediation Works on Site
Note:
Due consideration should be given to the impact of remediation
works on adjoining buildings and any shared structural elements
eg. Party walls. In this regard, the sequencing of works should
be carefully planned. It is good engineering practice to
remediate all affected parts of buildings and adjoining buildings
concurrently. (See Clause 4.2 IS398:Part 2)
Monitoring the Remediation Works on Site
2. Enabling Works

All relevant services shall be isolated by suitably qualified personnel and the service locations recorded to
facilitate reinstatement later;

Adequate protection shall be provided to the building and its surrounds as appropriate i.e. windows,
external doors and sealing off of upper floors;

Works shall require the removal of all fixtures and fittings including sanitary ware in the area affected.
These should be stored for later reuse, if possible, following remediation;
Note:
It may be prudent to take, and store, samples of finishes such as carpet, floor tiles and timber flooring.
Such samples would then be available for comparison purposes at reinstatement stage.
Note: It will be necessary to form an opinion on the condition / suitability for reinstatement of some of the
fixtures and fittings.
Enabling Works
Enabling Works

Temporary support or bracing of non-structural elements shall be provided as specified in the RWP e.g.
stairs and internal partitions etc;

Floor finishes on the ground floor including timber boarding and floor tiles shall be removed; - it may be

Remove sections of internal plasterboard as required in the RWP to facilitate appraisal of damage. This
may require the RWP to be amended in the form of written instructions if necessary.
prudent to take, and keep, samples of the timber flooring, carpet and floor tiling.
Enabling Works
Note:
It may subsequently be found that cracks have closed or partially closed. This may influence the
extent of remedial works required.
RECORDS SHALL BE MAINTAINED.
Enabling Works
3. Removal of floor slab and hardcore material (internal and external)
●
General
•
The junctions between the floor slab and the walls shall be assessed. If the floor slab is isolated from the
wall, the slab shall be removed. If the floor slab is not isolated from the wall a projection of slab adjacent to
the wall in accordance with the RWP shall be retained to facilitate subsequent integration with new floor slab;
•
Remove and dispose of concrete floor slab
Note 1 :
The preferred option is to use saw cutting.
Removal of Floor Slab and Hardcore Material
(internal and external)
Removal of Floor Slab and Hardcore Material
(internal and external)
Note 2 :
When removing concrete floor slab it is of critical importance that the integrity of the existing radon
membrane / DPM at the locations where it is to be lapped or connected with the new membrane DPM is
protected.
•
Inspection shall be carried out at this stage to determine that there is adequate support for all walls – is any
temporary support required?
RECORDS SHALL BE MAINTAINED OF THE INSPECTION
Removal of Floor Slab and Hardcore Material
(internal and external)
•
The insulation, DPM / radon membrane shall be removed. A recommended minimum 250mm lap shall be
maintained of the existing DPM / radon membrane around the walls for reinstatement purposes. This lap
shall be protected through all stages of the works.
Removal of Floor Slab and Hardcore Material
(internal and external)
Note:
In some instances where a separate screed is provided, the insulation may be above the floor
slab.
Removal of Floor Slab and Hardcore Material
(internal and external)
•
The hardcore material under the concrete floor slab within the building, and to a minimum of 500mm (or
as specified in the RWP considering the site conditions) from the external faces of perimeter walls and/or
projecting concrete footings, shall be removed completely.
-
Temporary support or bracing of structural items shall be provided as necessary. Consideration
shall be given to the avoidance of excessive level differences on opposite sides of walls.
Removal of Floor Slab and Hardcore Material
(internal and external)
•
All existing services, including heating pipes shall be protected – or removed for replacement at a
•
The radon sump and piping shall be removed.
•
Blockwork rising walls shall be brushed clean.
•
Inspections shall be required to confirm that all particles of the original hardcore and any embedded
particles in the subsoil are totally removed. The inspections shall be carried out by a design
professional.
subsequent stage.
RECORDS SHALL BE MAINTAINED.
Removal of Floor Slab and Hardcore Material
(internal and external)
•
Disposal of the excavated hardcore.
-
The management of waste consisting of pyritic hardcore is subject to statutory obligations
covered under environmental legislation particularly with the requirements of Sections 34 and
39 of the Waste Management Act, Waste Management Act 1996 (No.10 of 1996) and Waste
Management (Amendment) Act 2001 (No.36 of 2001). Alternatively, the pyritic hardcore shall
be managed, where appropriate under certain specified circumstances, taking account of
Article 27 of the European Communities (Waste Directive) Regulations 2011.
Removal of Floor Slab and Hardcore Material
(internal and external)
4. Determination of Works to Substructures
• Assessment of Works
-
Substructure inspections shall be carried out to determine if repair is necessary. The
inspections shall be carried out by the design professional.
RECORDS SHALL BE MAINTAINED
-
Substructure elements such as rising walls and strip foundations etc., shall be examined for
defects including sulfate attack, cracking, movement of blockwork of any other defects. The
resolution of this damage may require repairs as specified in the RWP or as instructed by the
design professional.
Determination of works to substructures
-
If inspection determines that sulfate damage is present, remediation may be deemed necessary
by the design professional
Note:
Typically this may involve scabbling the rising walls and rendering with a protective
coating or replacement.
-
Following assessment of works, the RWP may need to be amended in the form of written
instructions if necessary.
•
Repair works to substructures
-
Following completion of any necessary repairs, an inspection shall be carried out to confirm
that the repairs are adequate. The inspection shall be carried out by the design
professional.
RECORDS SHALL BE MAINTAINED
Determination of works to substructures
5. Installation of replacement hardcore and underfloor services
•
General
-
Replacement hardcore shall conform to I.S. EN 13242 and Annex E of S.R. 21:2004+A1:2007 and any
other requirements of the RWP.
-
Specific guidance is given in 3.4.2 of S.R. 21:2004+A1:2007 on limiting the presence of a reactive form
of pyrite which may give rise to swelling or sulfate attack on concrete.
-
Prior to receipt of replacement hardcore, appropriate documentation confirming its source and
suitability for the intended use shall be submitted to the design professional for review.
Installation of replacement hardcore and
underfloor services
Installation of replacement hardcore and
underfloor services
•
Placement of hardcore
-
Prior to the placement of the hardcore, it shall be visually inspected by the design professional and he
shall direct further testing if necessary.
-
Scale of the works may suggest particular on-site sampling and testing.
-
The new hardcore shall be placed in accordance with the RWP.
-
Finished depth of hardcore shall be a minimum of 150mm. In confined areas such as dwellings the depth of
hardcore should be limited to a maximum of 900mm.
-
Suitable concrete may be used as a sub-base to raise levels to ensure this maximum of 900mm depth of
hardcore is not exceeded.
-
Typically hardcore shall be placed in layers not greater than 225mm maximum in thickness and levelled and
compacted using a mechanical plate compactor. Care shall be taken in areas of local deepening such as
foundation trenches.
-
Care shall be taken to avoid damage to existing structural elements and possible differential filling on rising
walls.
-
Following completion of the placement of the hardcore, inspections shall be carried out by either the
builder or design professional.
RECORDS SHALL BE MAINTAINED
Installation of replacement hardcore and
underfloor services
•
Underfloor services
-
Underfloor services (including radon sump and associated pipework, drainage services, utility
services) shall be reinstated as the filling of hardcore progresses as specified in the designer’s
RWP.
-
Reinstatement works shall ensure that all pipework is clear (by rodding) and properly
connected.
Installation of replacement hardcore and
underfloor services
6. Preparation for laying ground floor slabs
•
Blinding Layer
-
A blinding layer shall be provided in accordance with the specification given in Annex E of S.R.
21:2004+A1:2007
•
Radon membrane / DPM
-
The radon membrane / DPM shall be reinstated.
-
Reinstatement shall ensure that laps, edges, joints and service penetrations are effectively sealed in
accordance with the RWP.
-
Inspection shall be carried out by the builder or design professional.
RECORDS SHALL BE MAINTAINED
Preparation of laying ground floor slabs
Preparation of laying ground floor slabs
•
Floor Insulation
-
Install adequate floor insulation in accordance with the RWP.
-
Inspection shall be carried out by the builder or design professional.
RECORDS SHALL BE MAINTAINED
•
-
Services
Services within the floor slab shall be reinstated as works proceed and tested as specified in the RWP.
Preparation of laying ground floor slabs
Preparation of laying ground floor slabs
7.
Laying of new concrete floor slab
-
Where there are sections of original concrete floor slab remaining, the joint between the new and existing
slab shall be made in accordance with RWP. This may involve scabbling, dowelling etc.
-
The thickness of the concrete floor slab, grade of concrete, support conditions and reinforcement details (if
required) shall be specified in the RWP, taking into account whether the floor slab is ground bearing or
suspended in-situ.
-
The concrete supplied shall be in accordance with I.S. EN 206-1.
Laying of New Concrete Floor Slab
-
Consideration should be given to the use of admixtures to reduce the water cement ratio of the concrete
which may result in speeding up the remediation works.
Note: When using admixtures, care should be taken in terms of the curing time of the concrete and the
implications for site workability of the concrete.
Laying of New Concrete Floor Slab
8. Structural repairs above ground floor slab level (internal and external)
-
Prior to commencement of repairs above ground floor slab level, the design professional shall review the
RWP, and the superstructure, to determine any revisions that may be necessary as a consequence of the
remedial works to date, and issue amended written instructions if required – it may be found that cracks
have closed or partially closed. This may require the RWP to be amended in the form of written
instructions if necessary.
-
All repairs shall be carried out in accordance with the RWP.
Following completion of the repairs, an inspection shall be carried out by the design professional.
RECORDS SHALL BE MAINTAINED
Structural Repairs above ground floor slab
(internal and external)
9. Reinstatement
-
Reinstate services, internal non-structural elements, fixtures and fittings, including sanitary ware
previously removed as specified in the RWP.
Note:
In cases where the works are carried out in a compressed timescale due recognition should
be given to the installation of moisture sensitive floor finishes.
Reinstatement
10. External Works to the immediate environs
-
The external immediate environs (to a minimum of 500mm from face of external walls and/or
projecting concrete footings) shall be reinstated in accordance with the RWP.
-
In some cases it may be decided to remediate the entire site curtilage
-
Following completion of the works, an inspection shall be carried out by the design
professional.
RECORDS SHALL BE MAINTAINED
External Works to the immediate environs
External Works to the immediate environs
11.
Inspections, testing and records
-
During the remediation works inspection and testing shall be carried out as specified in the various
clauses of this standard, and records shall be maintained.
-
The design professional may specify further inspections, tests and records, and these shall be specified
in the RWP.
-
Inspections shall be carried out by either the builder or design professional as specified.
-
Records can include paper or electronic records, photographs, videos.
Note 1
:
Inspection criteria to be specified in the RWP.
Note 2
:
Testing to be specified in the RWP.
Inspections, testing and records
Stage Valuations
12. Stage Valuations
-
It is likely that interim payments will be made to the Builder at key stages. Such stages may
include the following:-
-
Completion of repair of rising walls (X %)
-
Completion of installation of floor slab (Y %)
-
Completion of works (balance less retention)
Stage Valuations
13. Issue of Certificate
-
Following the completion of the remediation works, a Certificate of Remediation shall be issued (see
Annex B)
-
The Certificate shall be issued by the design professional who inspected the works in accordance
with the requirements specified in this standard
-
The builder shall complete the relevant sections of the Certificate in Annex B
Issue of Certificate
Issue of Certificate
Issue of Certificate