Flat roof extensions can provide a simple, cost-effective solution that ticks all the right boxes, especially for many smaller extensions. The comparative ease of constructing flat roof extensions, as well as their discreet visual impact, can prevent you having to shell out for a more expensive tiled roof in many cases.
Flat roofs can also come in handy where using a bulky pitched roof would overshadow or block existing windows. There may even be an added bonus where the space can be utilised as a balcony, subject, of course, to planning permission and Building Regulations.
The main concern with flat roofs is their unenviable reputation for developing problems. Unless carefully designed and constructed they are notoriously prone to leakage and heat loss, along with defects like sagging decks, ponding water and prolific plant growth. All of which may explain why mortgage lenders and insurers have a tendency to be wary of properties endowed with large areas of flat roofing.
Thankfully, such concerns can be dispelled by taking the trouble to consider the three main aspects of flat roof extensions: the structure, insulation and coverings.
GETTING THE STRUCTURE RIGHT
Extension flat roofs are normally constructed like timber floors, in essence comprising a series of joists with a timber deck plonked on top. Obviously, it’s essential to get the size, type and spacing of joists right. (These can be calculated with reference to published span tables — see the Right Survey website.)
Building control will normally require a structural engineer’s calculations to demonstrate that the completed
