Expert Witness Report by RICS Chartered Surveyors Derby

Photographs from an Expert CPR35 Report by our Derby Surveyors on a collapsed wall where the neighbours disputed the cause of the collapse.

A general view of the collapsed wall. The owner of the higher ground level who owned the wall had an engineer's report claiming that drains under the slabs shown had caused the foundations of the wall to rotate and that this together with the weight of the retained ground caused the wall to collapse. Our Derby surveyors soon showed different.

A view of the wall looking the other way. What can not be seen is that the wall leans along its whole length.  This would be unusual in a drain failure. Normally the drians fracture or collapse in a small area and movement above is confinded to a small section of wall or floor. Another important point is that although the wall is constructed of sepaerate brick and block leaves there is no evidence that they were tied together and so acted seperately.

 Here the wall has remained upright as it is retianed by the wall that can bee seen to the left and there was an expansion joint in the wall. The blocks appear to be behind the brick wall at its base but project beyond the rear of the bricks at the top. The fill behind the wall is interesting as it is gravel. Walls are normally pushed over by wet clay as it is very heavey particuarly if it expands as it get wetter.

Three trial pits were dug at the ends of a garge and in the centre.

The wall had a very good foundation which can just be seen to the right of the hole. The drian is bedded in gravel along its length so that should it fracture there is an easy path for the water to follow.

A vertical level shows the widening gap towards the bottom of the wall.

This level however shows that the wall is entirely in plumb below ground level.

Our surveyors concluded that the likely cause of the collapse was that the wall was badly constructed. The two leaves of the wall were able to act independently of each other so that one leaf was easily puched onto the other by the fill. The ground under the slabs had held the wall in plumb below ground level. A drains report also showed that the drians were in very good condition.