BWF members such as yourselves frequently use our Member and Technical Helplines for assistance on a wide range of Employment, Health and Safety, Contractual and Technical issues. We’re putting up a frequently asked question every Tuesday in order to help members and illustrate the type of advice we are able to provide. If you have any questions that you would like to see featured, we would be happy to assist. This question and many others like it can be found in our Question Centre. If you want further advice on any of the issues, don’t hesitate to ring the helpline or browse our extensive publications library, which includes our information on Installation, Building Regulations and Maintenance. This week: What Should I Expect a Customer to Know About the Product They Ask For? Our technical team frequently receive enquiries regarding the specification of products. Often these enquiries are made to gain information on an aspect of the performance of a product when this feature has been disputed by a customer. Too often, the dispute has come about due to a lack of information at the outset of discussions between the supplier and the customer, and a common theme in these disputes is that the customer considers the supplier to be an expert and to have taken into consideration all aspects of the work in hand, and the supplier often over-estimates the understanding and expertise of the customer. To reduce the likelihood of a problem later on, it is best to provide as much information as possible to assist the customer. This should cover aspects such as the performance of the product, quality of materials, the affects of changes in moisture content, and advice on storage, installation, finishing, glazing and maintenance. One aspect to consider, however, is that it would be best to present the specification in a written form and at a level that is achievable rather than by way of a high quality sample if the sample is not truly representative of the products that the customer will receive. The performance of a product needs to suit the conditions in which it is to be used. In my last Join-In article, which discussed glazing, I referred to a site exposure rating. For external doors and windows, there is a correlation between the exposure rating and the weather performance of the product which is determined by testing in accordance with BS 6375-1. External doors and windows fitted in a house located in open country, near the top of a hill in the Lake District will need to withstand more severe weather conditions than a similar product installed in a property in central London. A stair fitted in the common areas of a block of flats will need to withstand greater applied loads than a stair fitted in a private dwelling. When agreeing the quality of materials, all joinery items should have their material specified in accordance with BS EN 942. This standard describes various ‘J’ classes which contain, to varying degrees, features or defects such as knots and splits. There should also be agreement whether the material can be laminated and whether it can contain finger-joints. There are also controls on the minimum density of timber and moisture contents should be checked to ensure it matches the in-use conditions. It is worth noting that there is no correlation between the Scandinavian Grading Rules and the ‘J’ classes. A high grade J10 component can be manufactured from fifths grade material, but a lot of waste may be created in the process. When products are supplied to site, it is best if these are completed to the greatest extent possible, as this reduces the problem of poor site work later on and adds the opportunity for increased revenue from the added value aspects of finishing and glazing. Unfinished products should be finished as soon as possible to prevent the surfaces of the timber degrading. Glazing should only be applied to prepared timber and never to bare surfaces and hardware is best applied on to finished items to ensure that the surfaces beneath the hardware or within cut-outs are finished as well. If products are supplied in winter, the external conditions may be too cold or wet to undertake finishing or glazing satisfactorily. Once delivered to site, if they are not to be installed straight away, products should be stored in suitable conditions which will not make them deteriorate in any way. They should be stored either upright or supported to prevent them from distorting, kept at a reasonable moisture content, preferably in naturally ventilated conditions with plenty of air movement and protected from sunlight until they are properly finished. Customers’ attention should be brought particularly to the fact that internal doors, fitted into newly built properties that are being forced dried using heaters during the day, will be affected by the condensation which forms when the warm humid air cools overnight once the heaters are switched off and all the doors and windows have been closed.