Garden walls are exempt from control under the Building Regulations.
However, planning permission may be required if the proposed wall is to be more than 2 metres in height. If the wall is to be built in a conservation area or in the vicinity of a listed building, Listed Building consent is likely to be required as special considerations apply. Similarly, if an existing wall in a conservation area or near a listed building is to be demolished, consent is likely to be required.
If garden walls are not properly built, they can become dangerous through instability, settlement and cracking. Local authorities receive many calls every year reporting defective or dangerous walls. These defects can generally be prevented by good design, construction and maintenance. This note aims to provide common sense advise on good practice so that safe and satisfactory garden walls may be built.
There are circumstances where further guidance is necessary, such as where a wall is to be built in areas of poor ground conditions, on sloping sites, walls where ground level is significantly higher on one side of the wall (i.e. the wall is a retaining wall) and where a wall may be subject to additional loading (such as vehicular impact damage, supporting a door, gate or a sign of significant weight).
It is worth bearing in mind that more robust construction is necessary in exposed areas than in those that are sheltered.
Foundations should be taken below topsoil onto a firm substratum.
Concrete for foundations should have a minimum mix of 1:3:6 (cement: sand: ballast).
Mortar should have a minimum mix of 1:6 (cement: sand). It is recommended that a plasticiser be used in the mortar.
The guidance is for walls with restraining piers at each end.
Movement joints should be provided at centres of not more than 6 metres in blockwork and at centres of not more than 12 metres in brickwork. Movement joints should incorporate lateral ties for restraint. Brickwork walls constructed using sand-lime mortars do not need movement joints because of their greater capacity to accommodate movement. This should be borne in mind in designing garden walls, as ground movement is a frequent occurrence due to the activity of tree roots or other factors.
Walls in exposed sites typically are subject to more rainfall, more wind loading and greater changes in temperature (and thus greater thermal movement) than are walls in sheltered sites.
Half brick or 100mm blockwork walls should have foundations of at least 375mm in width, bearing onto a firm substratum. Piers should be provided at centres not exceeding 2 metres. The maximum height should not exceed 725mm (525mm on exposed sites).
One brick or 215mm blockwork walls should have a foundation of at least 525mm in width. The maximum height should not exceed 2 metres (1.5 metres on exposed sites).
One and a half brick (330mm) walls should have a foundation of at least 600mm in width. The maximum height should not exceed 2.7 metres (2.4 metres on exposed sites).
If foundations are to be eccentrically loaded, they should be designed and built to resist the overturning moment that will occur as result of the eccentric loading.
For shallow earth retaining walls, the following points should be observed:
- The wall should be monolithic.
- The earth being retained must not be allowed to become saturated. Either land drains should be provided in the earth being retained or weep holes provided in the retaining wall.
- The depth of ground to be retained must not exceed four times the thickness of the wall.
- The combined loading at the base of the retaining wall should not exceed 70kN per metre run of wall.
Vertical or diagonal cracks of up to 3mm in width generally do not adversely affect the stability of a wall. The cause of any cracks should be established before repointing a wall. Loose masonry will need to be rebuilt.
It is the owner’s responsibility to ensure that a wall is maintained in a safe condition.
If you are concerned about the stability of a wall in an area to which the public have access, e.g. adjacent to a highway, you should report the matter to the local authority.
This guide is produced for general guidance in the London Borough of Waltham Forest. It is not a substitute for a proper structural design carried out by a suitably qualified and experienced engineer or surveyor.
The authority does not accept any liability for walls designed in accordance with this guide.
This guidance was correct at the time of writing (September 2011).
Contact us
Building Control
Environment and Regeneration
Waltham Forest Council
Sycamore House
Forest Road
London E17 4JF
Tel 020 8496 3000
Email building.control@walthamforest.gov.uk
