66 RCI 0514

RCI May 2014

FLAT ROOFING & FLEX SYSTEMS documented advice and British Board of Agrément certification.” The above is clear in principle, however in practice zero pitch / completely flat roofs and roofs with ponding are an everyday reality, and measures need to be taken to deal with the issues created. Dealing with the issues Waterproofing: If the membrane is designed to be resistant to standing / ponding water, is not damaged by long term interaction with water, and is not damaged prior to being submerged beneath the water, this should not be an issue. What may be an issue is if the waterproofing itself has potential weaknesses such as laps or seams, or simply that it may be damaged by hydrolysis, which can simply be defined as the chemical breakdown of a compound due to reaction with water. We would recommend that specifiers and contractors are careful to ensure that the selected waterproofing manufacturer is entirely comfortable with the potential of standing / ponding water, whether planned or not, and that if this situation arises, there are no exclusions from any warranty or guarantee. Structural: Loading issues and deflections where they may cause structural damage must be avoided, and if a roof is designed to hold water this should be included in the structural design calculations. If the roof is either designed for the load or there is sufficient redundant capacity to Roofing Black and White EPDM, Rubber Seam, Flashing and Cover Tapes, Bonding Adhesives, Caulking and Accessories 066 MAY 2014 RCIMAG.COM “In practice, zero pitch / completely flat roofs and roofs with ponding are an everyday reality and measures need to be taken to deal with the issues created” withstand the load, this issue can also be dealt with subject to design / assessment by a suitably qualified structural engineer. Safety: As with any working environment and every instance of working at height, it is critical that risk assessments are carried out in accordance with the principles laid down by the Health and Safety Executive. U-Values: Thermal performance of inverted roofs may be affected by the rainwater cooling effect, but there are acknowledged mechanisms with water reducing layers and the option to adjust UValues to deal with this. BS 6229:2003 (under review): This standard was introduced approximately 11 years ago and in this time both waterproofing technology and concepts of roof design have evolved. With interest in completely flat roofs and designs such as Blue Roofs (roofs explicitly designed to attenuate and possibly store / hold water), the potential for having to deal with water on the roof, either planned or unplanned, is something that the industry is likely to need to continue to deal with. The way forward Clearly there are demonstrable advantages to creating positive falls on roofs to prevent ponding or standing water and avoid the issues detailed previously. There are also instances where this does not happen either by planned design, for example Blue Roofs, or unplanned, as a result of errors or omissions in the design or construction. Introduction of a cut to falls scheme, crickets to divert water, or additional outlets may not always be possible or effective, and the fact remains that a consequence of waterproofing a roof may be the creation of areas where water collects. As a liquid only specialist for more than 30 years, we have extensive experience of waterproofing all types of roofs, many of which are subject to long term standing / ponding water. We also regularly use the same roof waterproofing systems to waterproof water-retaining structures, from fountains to duck ponds, where the waterproofing is permanently submerged. We would suggest that if ponding / standing water is likely or even possible, specifiers and contractors ensure that they fully understand the implications, and ultimately ask the question of the waterproofing manufacturer; will this compromise any warranty or guarantee? www.triflex.co.uk LottesRoofing “Quality Roofing Since 1919” Lottes Tapes 15% BELOW WHOLESALE! SPECIAL UK pricing Works on EPDM, TPO and PVC! 20 Year Warranty ASTM Approvals Pallet Pricing Contact us on 001-480-442-1307 Email david@lottescompanies.com www.lottescompanies.com


RCI May 2014
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