080 GGP 0113

GGP JAN 2013

TRADAREPORT Stopping the rot Tand poorly organised storage are majorimber is one of the most commonmaterials on a building site but is oftenone of the least respected. Bad handling causes of damage and wastage. This has a consequent impact on costs, particularly for ‘specials,’ or materials with a long delivery time as replacements, or remedial works, may delay completion and result in financial penalties. However, the problem of material wastage is not just a financial issue, it is also an environmental concern and with the current high emphasis on sustainable construction, it is important to take all reasonable measures to reduce it. This is covered in a new Wood Information Sheet from TRADA, Care of timber and wood based products on building sites. MOISTURE CONTENT Wood naturally contains moisture; the amount varying with the temperature and relative humidity of the surrounding air. Any mismatch Nick Clifford, TRADA, looks into the dos and don’ts between the moisture content of the wood and its surrounding environmental conditions can when dealing with the care of timber and wood based lead to changes in dimension as well as some products on building sites. physical and mechanical properties. All wood based products, including external joinery To avoid prolonged site storage and double manufacturer for as long as possible but these products like timber windows, as well as solid handling, phase delivery to coincide with the may be insufficient for outdoor storage without wood, are subject to this change to some degree. progress of work. Use suitable handling methods further protection. It is particularly important when timber products to ensure that timber and wood products are not Treat factory finished components, such are used in a centrally heated building. damaged during loading, transit and unloading. as kitchen units and fitments, in a similar Observing a few simple rules about the correct manner as for internal joinery and flooring. specification of moisture content and careful site STORAGE OF JOINERY Particular care is necessary to avoid damage to storage can avert ‘drying out’ problems, such as Joinery, including wood windows, is a precision completed units. shrinkage, distortion and staining. In situations made and costly building component that involving high class joinery or other prestige should be treated with respect. TRADA’s WIS 4- TIMING IS CRITICAL work, proper care takes on special significance. 16: Timber in joinery highlights the importance Build to a programme that protects timber and of specifying and maintaining the right moisture joinery from the wet. Do not allow floor joists TIME OF INSTALLATION content in joinery. and roof timbers to stand exposed to the It is desirable to introduce all timber and wood Treat external joinery in a similar manner as elements for longer than necessary. based products into the building at their in- for structural components. Choose support Glazing before fixing floorings, linings and service moisture content but in practice, this is carefully to avoid distortion due to unnatural joinery, minimises the possibility of timbers rarely possible. Nevertheless, if timber is ordered loading. Priming offers little protection against being soaked and therefore reduces the so that the recommended moisture contents are the uptake of moisture. Should any projections, likelihood of excessive shrinkage and twist. Plan not exceeded at the time of installation, most or any other sections of primed timber be cut deliveries to coincide with progress of work so as shrinkage should not be a significant problem. off, re-prime the exposed bare timber. Similarly, to avoid prolonged site storage. Prepare storage For wood windows, this moisture content is in the case of preservative treated timber, coat in advance. between 12%-19%. Creating and maintaining any cut ends, borings and notchings liberally Check the quality, specification and moisture the correct site conditions is important for with preservative. content of timber as well as its condition and controlling moisture content. Ideally, keep internal joinery and flooring finish at the time of delivery. This is the time to in a heated dry store to maintain the correct raise any issues with the supplier. CARE AT ALL STAGES moisture content. Ensure that proper protection has been Joinery and other wood products should be If that is not possible use a garage or other afforded to the material in transit. manufactured with the timber at the dry and weatherproof storage area, providing Use proper mechanical handling equipment recommended moisture contents. If wood it is well ventilated. The stored components whenever possible. Do not damage the product, products have to be stored before delivery to site, should not rest directly on fresh concrete especially edges, corners and wrappings that the manufacturer should keep them in and the material should be close piled and should be maintained as long as possible. conditions that will maintain the correct fully wrapped. Instruct and train handlers and always supervise moisture content. Goods should be adequately In general, store joinery items flat on closely off loading. protected during transit. This should ensure spaced bearers but in all cases follow the that they are delivered to site at the correct manufacturer’s recommendations. Retain For further information, visit the website: moisture content. protective coverings supplied by the www.trada.co.uk 80 January 2013 Glass & Glazing Products


GGP JAN 2013
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