PROTECTING NEW BRICKWORK AND BLOCKWORK
At the end of every working day, newly laid brickwork or blockwork should be protected from the actions of rain, frost or snow. Rain will wash unset mortar from the joints, leaving stains down the face of the wall, while icy conditions will cause the water in the unset mortar joints to freeze and then expand, causing irreparable physical damage to the new brickwork, particularly if the top of the wall is allowed to become saturated. Allowing the top of the wall to become saturated can also increase the likelihood of free lime leaching from mortar joints (causing the effect known as lime staining). It may also lead to unsightly efflorescence, which occurs when soluble salts from the brickwork remain on the face of the wall following drying out. The action of the sun in hot weather cannot be ignored either. High temperatures in summer can cause mortar joints to dry out too quickly, before the cement has set. This problem is
The prevailing weather conditions will dictate the method used to protect new external walling; there are various approaches that can be taken.
During periods of wet weather, the brickwork should be protected with polythene sheeting, weighted down on top of the wall and at ground level with timber boards or scaffold battens. In addition, inclined timbers are leant against the wall every metre or so, in order to hold the polythene away from the faces of the wall. This creates an airspace that allows the wall to breathe, creates some ventilation and avoids condensation forming. Condensation can be just as injurious to the wall as rain. The need to create some ventilation in this way is common to all the protection methods, regardless of weather conditions. During warmer months, the action of rain is less of an issue, but it is worthwhile protecting against the detrimental effects of sun and wind by draping the wall with damp hessian. Ensure the hessian is not too wet, as this can result in staining from the mortar joints. The main problems during winter are frost and rain, meaning that the wall has to be kept insulated and dry. This is achieved by using dry hessian for insulation, with polythene sheeting placed over it. The polythene keeps the hessian dry so it retains its insulating qualities, and ensures that the wall is kept dry at the same time.