Professional Plaster and Drywall Services in Barnstaple

Apart from the adverse effect it has on the environment in general, cement mortar is usually hard, brittle and less porous than lime mortar. It often contains additives to make it sometimes completely waterproof and is damaging to traditional buildings for several reasons. Cement mortar is often harder than old bricks, cob or some types of stone, therefore when movement occurs it may damage these softer traditional construction materials. Hard cement mortar can trap moisture behind it causing damage to the structure and encourages ground water to rise up a solid wall by capillary action. Trapped water in the wall can cause poor insulation, decay and crumbling. In severe cases a cob wall can fail. The brick, cob or stone can also be subject to frost damage if moisture levels are to high.

Animal hair, usually horse, cow or goat, is added to the backing coats of lime mortar used for external rendering or internal plastering onto stone, cob, brick or timber lath. Adding hair gives extra strength and minimises shrinking and cracking. This allows thicker coats to be applied to uneven walls and holds the plaster keys in place when plastering onto lath.

The materials cost a little more and some firms will also charge a premium for lime work. In the long run using the right materials is less expensive than causing damage to the building.

For lime putty mortars, the sand used for building, pointing and backing coats of render and plaster should be a washed sharp coarse sand. We use a sharp sand to BS882 which is free of vegetable matter, clay and salts. For finishing coats of internal plaster we mix a very fine, kiln dried sand with the lime putty.