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Building Products October 2017

DAMP PROOFING, SEALANTS AND ADHESIVES furthermore, EWI can lead to rising damp reaching a greater wall height – typically no more than 1.5m – than is usually the case. The issue of rising damp stems from most solidwalled housing in the UK being built before the 1920s and before installing a damp-proof course became common practice. Not all these properties will suffer from rising damp, yet it is far less expensive and disruptive to conduct a survey – and tackle the causes of damp present at that stage – than to be faced with complex and costly remedials post-EWI installation. The nature of the issue is explained in the BRE’s 2016 report Designing Out Unintended Consequences When Applying Solid Wall Insulation by Colin King and Caroline Weeks. The authors relate that “There have been reports of increased condensation and mould growth and other undesirable effects within some homes following such insulation measures”. With the introduction further stating that “As installing such measures becomes more common, it is imperative that stakeholders properly appraise the risks that may be associated with these works”. Cavity Wall Insulation (CWI), although not targeted in terms of numbers of installations like EWI, must be subject to similar concerns. Again, it is a highly effective measure that improves the energy efficiency of housing stock and cuts carbon emissions. Yet it is vital to survey properties carefully before CWI installation too. Cavity walls were introduced primarily as a means of defending homes from penetrating 68 BUILDING PRODUCTS | OCTOBER 2017 damp caused by heavy rain. The thermal performance benefits of cavity walls, though, are hard to establish and cavity wall insulation (CWI) was introduced as a means of improving it. However, for CWI to be effective and not cause other problems, external walls need to be in good order prior to installation. This means cracks, mortar losses, poor pointing and other defects need to be rectified first; otherwise CWI will itself become wet through moisture penetration. This not only negates its insulation properties, it can potentially result in slumping and complete failure. This failure is almost always a function of the installation, rather than the products themselves. Incidentally, having ensured exterior wall condition is satisfactory, the application of a masonry protection cream will also prove beneficial to the overall installation. This allows the wall to breathe, while acting as a water repellent. Apart from underwriting the dryness of the CWI, it can also improve thermal performance the building as dry walls have better insulating qualities than wet ones – dry bricks have twice the thermal resistance of wet. Although the drop in funding for the ECO scheme is disappointing, its continuation and the measures proscribed – especially in terms of EWI and CWI – are to be welcomed regardless. But we must be mindful that, despite the considerable energy benefits these systems bestow, there cannot be an unthinking move to install them without proper consideration of building conditions first. <<< Continued from page 67 This implies a more holistic ‘whole-building approach’ to tackling damp issues is taken: a recent school of thinking extensively outlined in the BRE White Paper Moisture in Buildings: an Integrated Approach to Risk Assessment and Guidance by Neil May and Chris Sanders. As the authors say: “It is apparent that the current approach to moisture issues in standards, regulations and certification is inadequate and requires substantial review and revision. The current approach is based predominantly upon the idea of a building as composed of discrete building elements in perfect conditions, not affected by their interactions with other building elements (fabric and services) or by their context or use. In reality, most building elements interact in multiple and sometimes complex ways with one another, occupants and the external environment. Building materials are also affected by changes to their condition over time. The failure of the current approach to deal effectively with this reality has led to significant moisture risks. A new approach is therefore required”. Therefore it is a significant imperative to consider, detect and treat even the most minor cases of rising damp prior to moving forward with these programmes. Failure to do so will result in waste, expense, inconvenience and – possibly – homes that are even less accommodating to residents than before, thanks to exacerbated damp problems. Hudson Lambert is Director of Safeguard Europ


Building Products October 2017
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