Damp can occur in any building during its lifespan. There is however a tendency at present to ignore good building practice and this exacerbates problems with damp / water ingress into the building. These problems can be attributed to errors on the behalf of the architect and the builder, in the buildings the Association has inspected this year.

Penetrating Damp

This is caused by water penetrating the external fabric of the building. Contributing factors are the following:

1. Box gutters are under designed and the property owner does not clean the gutter on a regular basis.
2. Eaves are nonexistent or very small allowing rain to continually run down the external walls of the building.
3. Bad pointing in external face brick walls.
4. Not enough attention to detail on the sealing of window frames in a wall aperture.
5. Penetration of the waterproofing membrane by post completion installations, for example air conditioning units.

Lateral Damp

This is caused when the ground level outside the building is higher than the internal floor level and or the level of the damp proof course. Areas of a building that are susceptible to this problem are internal retaining walls, basements, cellars, lift pits and flower boxes. The following areas require specialist detailing and construction supervision.

1. Agricultural drains.
2. Waterproofing / tanking on the face of the retaining wall / flower box that receives the soil backfill.
3. Property owners should take great care of not over filling planter boxes above the design level.

Rising Damp

This is caused by the failure or bridging of the damp proof course in brickwork and penetration of the waterproof sheeting under floor slabs. The following should be observed by all builders in order that rising damp does not become a problem in the future of the building.

1. Use good quality embossed DPC that must be at least 375 um thick and make sure all overlapping joints are at least twice the width of the DPC.
2. Under surface bed plastic sheeting should be taped at the joints and precaution must be taken that reinforcing steel or anything else does not penetrate the sheeting.
3. If there is no face brick plinth below the DPC level a v-joint must be cut into the plaster at the DPC level to stop moisture bypassing the DPC.

R.H. Stembridge | Building Services manager