Garden Walls

Building Regulations - Your Garden Walls

Better To Be Safe.........

The Building Regulations do not apply to the construction of free-standing garden walls. You may however need to contact the Council's Planning Department to clarify if planning permission is required. They can be contacted on 01628 796050. Permission will also be required from the Council's Operations Unit for any excavations onto the public highway ie. for foundations, disturbing pavement surfaces etc. They can be contacted on 01628 683970. The structural design of the wall and its foundations will also need to be considered. Advice may need to be sought from a structural engineer. The Council has produced a design guide to help provide some advice, copies can be found at the Council's reference libraries or alternatively purchased from the Council ( priced £60 plus £2.50 p&p ).

Garden walls will eventually collapse if they are not properly maintained. Garden and boundary walls should be inspected from time to time to see if any repairs are necessary or whether a wall needs re-building.

Such walls are amongst the most common forms of masonry to suffer collapse and they are unfortunately one of the commonest causes of deaths by falling masonry. Your household insurance may not cover you if the wall has been neglected. Beside the general deterioration and ageing of a masonry wall over the years, walls may be affected by:-

• An increase wind load or driving rain if a nearby building is taken down or a protective tree screen removed.
• Felling of nearby mature trees or planting the new trees close to the wall.
• Changes leading to a greater risk of damage from traffic.
• Alterations and additions to the wall or removal of part of the wall e.g. for a new gateway.

Things to check

1. Is the surface of the brickwork crumbling away? If restricted to a few bricks this may not be serious but walls can be weakened by general crumbling across either face.
2. Is the mortar pointing in good condition? If the hard surface layer can be picked out from the joint or if the mortar can easily be scraped out with, say, a door key, then this is a good indication that the wall may need re-pointing.
3. Is there a tree near the wall? Clay (shrinkable) soils change volume as their water content changes. Soil has less volume change at greater depth. Garden walls usually have shallow foundations. Trees tend to increase the changes in water content of the ground. If a wall is cracked  and trees are nearby, it may be prudent to trim them. As trees mature there is a risk of the wall being damaged by the roots and from windblown branches. Damaged sections may have to be re-built, perhaps with 'bridges' incorporated to carry the wall over the roots. The removal of large trees can also lead to problems because the soil accumulates more moisture and expands. Even with no trees nearby, clay soils can damage a wall. If the damage warrants it, the wall may need to be rebuilt with deeper foundations, or repaired by adding vertical movement joints so that it can accomodate the movement without being damaged. Even in non-shrinkable soils, walls can be damaged by the presence of tree roots, which expand as the tree matures. Seek professional advice before cutting back roots, you may make the tree liable to collapse, or kill it. An alternative is to partly rebuild the wall so that it bridges the roots being supported on a lintel at that point. Cracking can also be caused by leakage from an adjacent drain.
4. Is the wall upright? Walls lean for a variety of reasons, due for example to failure below ground caused by tree roots, a cracked drain, frost damage to the foundations or inadequate foundations in the first place. If your wall leans to an extent that could present danger e.g. more than 30mm for a half brick wall, 70mm for a single brick wall, or 100mm for a brick-and-a-half wall, it is recommended that expert advice is sought. This may involve checking the wall foundations, rebuilding the wall in a more suitable form or adding structure at the side of the wall below the higher ground level to reinforce its strength.  Any weep holes in the wall to allow water through should be cleared if blocked. If the ground is higher one side of the wall than the other, the wall will have to retain the higher ground. It may have not been designed to do this, or may simply be inadequate.
5. Is the wall thick enough for its height? The table below gives guidance on how high walls should be relative to their thickness. You should seek expert advice if your wall exceeds the recommended height or in circumstances whereby this guidance is inapplicable e.g. walls incorporating piers, or walls supporting heavy gates or retaining soil.

   WALL THICKNESS	MAXIMUM HEIGHT
   Half Brick	525mm
   One Brick	1450mm
   One & a Half Brick	2400mm
   100mm Block	450mm
   200mm Block	1050mm
   300mm Block	2000mm

   
   *HALF BRICK = 100MM ONE BRICK = 215MM ONE & A HALF BRICK = 325MM

    6.   Some climbing plants, like ivy, can damage walls if growth is unchecked. Consider cutting them back      and supporting re-growth clear of the wall.

    7.   Is the top of the wall firmly attached? If the top of the wall is weather resistent the life of the wall will be enhanced. Any water in a wall can freeze causing cracking and loosening of masonry that further reduces the life of the wall, and loose masonry may then fall. Signs of damage here may indicate the need for re-building the top of the wall. Capping stones work best if they have overhangs and drips. Bricks work best if they are hard engineering bricks. Brick cappings or concrete copings may be loose or there may be horizontal cracks (frost damage) in the brickwork a few courses down. Loose or damaged masonry near the top of the wall will need to be re-built and should include a damp-proof course.

   8.    Has the wall been damaged by traffic? Minor scratch marks or scoring of the surface may obscure more significant cracks. Piers at vehicular entrances may have been dislodged by impact and be unsafe. In such cases we recommend expert advice should be sought and they should be re-built. If you think vibration may be the cause of damage, we suggest you also seek expert advice.

  9.    Are there any cracks in the wall? Hairline cracks 0-2mm across are common in walls and may not indicate serious problems, for wider cracks seek expert advice; some may indicate a need for partial or complete re-building. Seek advice on any horizontal cracks that pass right through a wall or any cracks close to piers or gates. Re-pointing of cracks can lead to problems. Do not re-point without establishing the cause of the cracking.

The Council under the Building Act 1984 has the power to deal with walls that are in a dangerous condition, so if you are concerned about a wall near where you live, please do not hesitate to contact Building Control Consultancy during office hours on 01628 796872, or alternatively out of office hours the emergency number is 01753 853517. Further guidance can be sought from our Dangerous Structures web page.

Than Sorry......

Further Useful Guidance

A leaflet published by the Department of Communities and Local Government (DCLG) is available to download below.

•   ODPM Garden Walls Leaflet (pdf) 124kb