The materials used to build and maintain a wall of a home directly influence its performance. The lime-based renders and mortars traditionally employed in old buildings ensure breathability and flexibility, so it is essential to use these when carrying out repairs. If cement-based products are substituted, damp problems are likely to occur and the property may be scarred visually.
Unlike the breathable lime mortar joints of old brickwork, cement mortar prevents the evaporation of moisture so, when the water expands during cold weather, the surface of the brick is stressed and breaks down. The same thing happens with render. Lime renders are breathable and accommodate slight seasonal movement. Cement renders will crack under stress.
Lime based renders and mortars were used on older properties as these are both breathable and flexible. Do not compromise the integrity and appearance of an old home by using inappropriate alternatives when carrying out essential external repairs
Illustrations Sarah Overs