Roof Design Advice
There are two main roof types - flat roofs and pitched roofs.
What's the difference? Here's the lowdown on each:
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Flat Roofs
Flat roofs generally have either concrete or timber decks. The traditional waterproofing method is two or three layers of felt laid onto hot bitumen, finished off with a layer of protective chippings. Modern alternatives use four layers of glass-reinforced polyester bonded permanently to each other and the decking, with no joints or seams. Flat roofs used to be designed as ‘cold roofs'; meaning the insulation is beneath the decking. However, nowadays the more popular construction of a flat roof is to lay the insulation on top of the decking and beneath the waterproofing layer.
Pitched Roofs
Most houses are designed with a pitched roof, as this is the most reliable and effective method to weatherproof a building. Historically pitched roofs were constructed on site from loose sawn timber. Nowadays, the more common form of roof structure is a pre-fabricated frame called a “trussed rafter”. These are predesigned and manufactured to meet the loading requirements of the building, taking into account span, roof pitch and weight of the roof tiles or slates. Unlike traditional roofs, where the purlins take much of the load, trussed rafter roofs are not usually suitable for conversion because to remove or change any component would weaken the structure.
One of the big benefits of pitched roofs has emerged in recent years as more and more homeowners have taken the opportunity to increase the number of bedrooms in the property by converting attic space into living space.