As we are coming into winter and the storm season, we thought we would look at this construction. This tends to be where a smaller fences are attached to the top of a wall to give height and privacy. This is often done without any thought for wind loading or design. The posts/fence supports are often fixed to the top of the wall in metal brackets such as met posts. The fixing is then screwed or bolted into the top of the wall.
This type of fix under load stresses the top course of the brickwork. Over time the fixing may well work loose. During violent or strong winds this will take down the fence and the upper courses of brickwork. The upper course of brick or blockwork tend to be the most vulnerable. These are the most exposed to the elements so on older walls the mortar is often weakened on these parts.
The other way of doing this tends to be bolting a timber fence post to the front of a wall. Again, with bolts or screws. During strong winds the bolts tend to act as levers.
This in turn will cause the wall to fail on the joints of the bolts, causing lager section of the wall to detach or at the very least loosen.
The rules for fences
Planning legislation applies as to the height you can erect walls or fences to depending on where it is on your property. We discussed this in the previous blog on fences. In addition to this the guidance on walls issues by the Government is discussed in a previous blog on boundary walls. This research was based on the Building Research Establishments work over many years and is based on wind loadings.
When installing a fence on top of a boundary wall, the entire height of both wall and fence must not be above the prescribed heights for a wall of the thickness of the lowest course of bricks. Base on this a fence should never be attached to a half brick thick wall, as combined it could only be an overall height of 45cm in Bristol. Similarly on a one brick thick wall combined it could only be 1.3m in height in Bristol.
Am my fence covered?
If your wall and fence hybrid were to fall down and the worst should happen. You would likely call your insurance company; we will look at this in more detail in a later series #amicovered. In reality as long as the fence and wall together are lower than the prescribed heights in the BRE category, and were in good condition prior to the loss. You would in theory be covered. However some insurance policies exclude damage to fences. So you may only be covered for the brick wall element not the fence.