A gable end wall is the triangular section of wall supporting two sides of a sloping roof. The phrase may also be used to describe the whole of the end wall of a building which includes a gable.
On most modern houses the roof tiles or slates extend over the top of a gable end wall, with some form of weatherproofing added between tile and brickwork to stop the ingress of rainwater. Bargeboards are often fixed to the horizontal timbers or Purlins of the roof when these rest on the top of the wall.
Gable end walls may also rise above the roof line, in which case Flashing must be inserted to seal the junction of the roof tiles or slates and the inner surface of the wall. Gable end walls rising above the roof line may be finished in a slope following the slope of the roof, or as stepped, corbel or Dutch gables. The wall should be capped or finished in such a way that rainwater runs off and cannot penetrate the wall.
Potential Gable End Wall problems
Because gable end walls rise above the level of the main walls of a building, they are susceptible to damage from high winds. This should not be a problem when they are properly braced, but if suffering from a lack of lateral restraint the following damage can arise:
- Outward bowing of the walls
- High level horizontal cracking
- In extreme cases, collapse of the wall
- Failure of the flashing or other means of waterproofing of the junction between the roof and the wall
On properties where the gable end wall rises above the roof line, the top of the wall should be finished in such a way that rainwater cannot permeate the wall. If this finish decays or cracks then water and frost action can severely damage the wall.
A survey will show any apparent defects caused by any of these problems, and suggest possible remedial action. If the surveyor considers that any gable end wall is not properly braced then bracing can be inserted in the roof space. However if a wall has already suffered damage it may be necessary to rebuild the wall as well as installing bracing.