Rev 3 – 14 01 15
TECHNICAL INFORMATION SHEET
Movement Joints
Movement joints in buildings are required to allow the structure some “give” and generally to avoid undue
stresses being created within the fabric of the structure.
These movement inhibitors/joints are generally created by placing 10mm joints through the wall section at
strategic locations within the building design which are generally at internal corners of buildings, specific site
lines or if possible they are hidden behind building features such as rainwater down pipes.
When a render system is applied to the wall, the movement joints must be mirrored through the render
system.
There is often a belief that when render has cracked it is because there has been movement within the render
itself but in most cases where a manufactured render system has been used it is because the structure that
the render has been applied to has moved which has caused the render to crack.
This is not always the case because if a very dense, hard render system is applied over a softer substrate the
render could in fact cause the substrate to crack. A common example would be rendering onto a very
lightweight 3.5kN block using a dense, cement rich render. E.g. Parex Parmurex, which is not a suitable render
for this substrate.
Parex avoids this scenario by producing a range of renders that are suitable for specific substrates. We always
advise the customer/Specifier to obtain a Parex specification first.
Assuming the correct render has been used, when the render system has been applied to a wall, it effectively
becomes monolithic and therefore becomes part of the wall. The wall being the stronger element, if it cracks
then the render is likely to crack too.
Based upon this principle if there is no movement joint created within the structure of the building, it is
pointless having a movement joint solely within the render.
As an example;
if there is a rendered wall 40m long that has no movement joints and it does not or will not move then the
render is unlikely to crack, however if the building moves and the wall cracks the render will generally crack
within or close to the same location as the substrate crack.

If we look back in time, lime mortar constructed buildings allowed movement to occur due to the
nature of the material. Generally these buildings did not have movement joints but do not show signs
of cracking (they may have moved out of level somewhat but indicate little or no cracking). This is
due to the nature of the lime materials used but this would be another lesson in its own right! For
additional guidance on lime renders and their uses consult the Parex brochure which offers full
guidance on lime applications.

Movement joints are generally a modern requirement due to the various types of construction
materials within the main substrates that are now in use. A range of application guidelines are clearly
PAREX LTD, Holly Lane Industrial Estate, Atherstone, Warwickshire, CV9 2QZ
Tel: 01827 711755 Fax: 01827 711330
Email: [email protected] Web: www.parex.co.uk
Registered in England No: 2450579
Rev 3 – 14 01 15
set out in the British Standards for masonry and timber structures. As initial guidance, these are
advised at every 6m or within 3m of any corner in masonry construction and every 15m and within
3m of any corner in timber frame construction. In steel frame construction, movement joints are
generally included to assist with the application.

Timber frame structures require additional consideration as frame shrinkage needs to be considered
in the vertical mode too and it is recommended that the roof is loaded first before the final external
render system is applied to allow for the frame to settle. This may require the addition of horizontal
movement joints on structures above two storey’s and will be determined by the building designer.
In addition, timber frames or timber based structures if left exposed to the elements, unprotected
for a period of time will generally take on moisture and expand, then once they are covered up do
have a tendency to shrink back quite rapidly initially. This factor needs to be considered before
rendering commences. Specialist render boards will provide an element of “give” too but this is no
substitute for good project management.

Steel frame structures are generally less prone to movement due to their inherent stability and thus
give minimal issues to render systems.

The use of an insulated render system will provide some additional “give” should the building
structure move because the insulation will assist in absorbing some of the stresses and due to the
ductility of the render system can allow the building more flexibility in design.
For additional information or other Technical Information Sheets, please visit our Web site link
http://www.parex.co.uk/Render_Systems/Technical_Information_Sheets_and_FAQs
Or for product datasheets contact;
Parex Ltd
Holly Lane Industrial Estate
Atherstone
CV9 2QZ
Tel: 01827 711755
www.parex.co.uk
PAREX LTD, Holly Lane Industrial Estate, Atherstone, Warwickshire, CV9 2QZ
Tel: 01827 711755 Fax: 01827 711330
Email: [email protected] Web: www.parex.co.uk
Registered in England No: 2450579