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Building Products January 2018

DAMP-PROOFING, SEALANTS AND ADHESIVES Hudson Lambert, director of Safeguard Europe, considers the issue of penetrating damp in new and converted properties, and how modern masonry treatments can solve this enduring problem. Water ingress into masonry is an ageold problem. Many building stones are naturally porous, and the external walls of many older properties – residential or non-residential – encountered in conversion will be constructed with bricks that are considerably more porous than would be permitted today. Walls constructed from porous materials soak up water every time it rains – often acting as a conduit for rainwater to permeate through to the inner face of the wall, where it presents itself as damp patches or blistering paintwork. They are also less thermally resistant than dry walls, which means that heat loss from the affected building is increased. Test work carried out by the University of Portsmouth showed that a modern brick lost half its insulation value when fully saturated with water, and a study by English Heritage has shown that the loss of insulation value can be even higher for more porous historic bricks – as would be the case using salvage/ reclaimed in new buildings. 52 BUILDING PRODUCTS | JANUARY 2018 Of course, not all rain penetration through masonry is caused by porosity of materials: defects such as cracks, faulty pointing, and poorly sealed doors and windows are a primary cause of many penetration problems. However, where masonry is particularly porous, it can be a major contributing factor and for this reason, there have been efforts over many years to develop products that can be used to reduce the permeability of such masonry. In new properties, defects are typically a function of craftsmanship issues, such as poor detailing and, for instance, poorly installed or designed proprietary dry verge systems that shed water onto gable end walls rather than taking it to the eaves (this can be identified by heavy streaking down brickwork). Remedial measures can be taken to waterproof porous brick in conversions and renovated properties, and to protect new brickwork with preemptive treatment; by way of applying colourless masonry water repellents that have been designed to reduce the permeability of masonry without affecting its appearance. Early attempts to achieve this kind of protection involved liquids made by dissolving waxes or linseed oil in solvent. These were simply painted or sprayed onto s masonry and could block rain penetration for a time. However, they were vulnerable to discolouration and could often become sticky and attract dirt. Their main disadvantage was that they worked by blocking pores of masonry, trapping moisture in walls and preventing it from evaporating. DEALING WITH DAMP


Building Products January 2018
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