SIPs (structural insulated panels) are a modular form of construction. They can be used on their own for whole house assembly or part of a more conventional timber-frame construction. The standard panels themselves are made of oriented strand boards or plywood sandwiching a rigid insulation core (such as urethane). In the layering there is a vapour-controlling membrane to keep moisture out. They normally have the thermal and sound insulation requirements to meet Building Regulations without the need for extra materials. But check with the manufacturer as the level of efficiency does vary. ‘Turnkey’ providers, companies that take the hassle of building a house away from the individual by providing as many services as they can, can ensure that the panels are even more ready to go. They will prefabricate the windows, include plasterboard on the inside of the panels and first-fit the electrics. Some will go the extra mile and organise bathroom and kitchen pods which arrive already to go on site. For any additional service, of course, there is additional cost. But the convenience and speed of build may outweigh the additional expense. For the exterior the individual self-builder can choose and arrange anything, such as render, brick or timber. In terms of cost, to supply enough standard SIPs for a whole house expect to pay around 15% more than a traditional timber-frame house. However, you may find this additional cost for the raw material is outweighed by the savings you make elsewhere. For example: the build will be a lot quicker, which will save you workforce expenses; the thermal performance should be higher saving you on your bills; and the wastage on your site will be a fraction of a typical build, saving you rubbish removal costs. For more information, BRE publishes An Introduction to Building with Structural Insulated Panels by J Bregulla and V Enjily for £9 and Modern Methods of House Construction by K Ross for £22.50, both available from www.brebookshop.com. For an extensive list of SIP and timberframe suppliers see pages 78-89 of this magazine.