Exactly that. We were thinking of having the back of the house extended (1.5m x 2.9m) to square off the kitchen/diner and have had quotes in excess of £20k!!! That's not doable right now especially as we'd like a loft conversion done at a later date that'd bring us to the ceiling price of the houses on our street but would give us the room we need for a growing family. Would it be worth getting a conservatory fitted at the back of the house instead?