We are in the pricing phase of this project. The builder has done an itemized estimate and I am double checking it to see if anything is unreasonably under or over. I do this by cross checking with numbers from local contractors and subs I have worked with in recent years. Some numbers are fairly hard such as $250/square installed for 30 year asphalt shingles. This is a number from local roofers used to estimate jobs. Another such number is $225/yard for concrete foundation. Painting and sheetrock have similar numbers. For other things such as labor, heating systems, electrical, flooring etc. I have to look at comps. This is where numbers from recent years and similar projects come in handy. I have found a very wide range when it comes to estimating. two years ago on a project, one overall estimate was 1 million and the other was 550k. I could then look at other past projects to see which was closer. I expect that if we had done two identical projects with each builder, the end number would have been well within a 10% difference. I also avoid cost per square foot numbers. Way too vague and innacurate. My preferred method is to find out how much can be spent, compare it to the wish list, judge then and there if it is possible, (it usually is not) then do some initial design and bring the builder on board to back me up when I say it can't be done for that $$. That sounds depressing but $100/square foot- which is what people usually expect - can only be done with some serious compromises and larger scale projects. My recent explorations into modular and prefab have born me out on this as well.