How much will an extension cost?
Building work will cost around £1,500 per square metre for the building work but as much as £3,000 per square metre for higher specifications. Bi fold doors can add £1,400 to £1,800 per metre for these. The interior can cost the same again, depending on the level of specification you require. The cost of an extension all depends on the level of specification you decide on.
It is important that you get quotes from at least four builders. It is almost certain that each of the builders will provide different costs for exactly the same work using the same materials. If you only approach one or two builders, you run the risk of only obtaining high quotes, rather than getting an idea of an average.
Whichever builder you choose beware oddly low quotes and ensure you get at least four references from previous customers for similar sized jobs.