I know I'm coming in late here however i'ed like to leave yet another warning. We went with the cheapest quote, got contract and drawings and yes building turned out to be too good to be true and the job has been completed but there are snags left untied up, sub contractors knocking on our door looking for payment and our builder looking for outrageous extras which he says we agreed to when we didn't. its a nightmare that you can do without. Get your contract even for something like a 10/20k build and pay an engineer if you are doing anything that if it goes wrong will render your house damaged.