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Leicester RICS Chartered Surveyors report on Structural Movement of a Gable Wall

Front elevation

Leaning gables apex

Deflection of the wall compared to a spirit level

Restraining strap

Strapping of the new wall to the roof structure

The property is a detached two storey house of solid brick wall and pitched slate construction constructed about 1925. The property is rectangular with a two storey projection at the rear.

The rear gable end of the main part of the property leans out about 150mm above first floor level. Measurement with a spirt level suggest that the top fifteen course of bricks lean out from above the point at which two large longitudinal structural roof timbers bear into the wall. The top ten course of the wall are of single skin construction and particularly vulnerable to further movement.

The wall only supports itself and the likely cause of the leaning wall is failure to restrain it at the time of construction. As it appears that the wall may move under the load of being pushed with a hand it should be restrained as soon as possible.

Remedial works are as follows

1. Demolish the top fifteen course of brickwork and rebuild them with a 225mm wall tied together with either bricks laid across the wall or metal ties. Straps set into the centre of the wall can be secured to the roof structure. The straps can be secured to the existing longitudinal timbers and to planks screwed across and perpendicular to the rafters just below each side of the apex.  18mm x 120mm x 2.4m floor boards or similar would suffice.

2. The existing wall can be strapped to the roof structure as described above with raw plugs. An inner leaf can then be constructed for the top ten courses and tied to the outer facer of the wall with metal ties cemented into raked out sections of the existing mortar.