Around Seattle where we work it is generally around $200-$250 a square foot to design and build a custom home of typical size on a flat site with good soils. Steep lots and bad soils can add tens of thousands of dollars before you’ve bought a single 2×4. That said, building may cost considerably more or less than that amount – dollars per square foot is merely a rough guide if you need one.
How much does Green Building cost?
$200-$250 a square foot is inclusive of most green building selections and strategies, although solar photovoltaics PV and geothermal heating can add a bit more.
Do I need a soils report before building?
Sometimes the building department will require a soils report before issuing a building permit, but not always. If you choose to have a soils report done before construction, you will have much better information about what your soils are like, whether they are adequate for your design, and how expensive your foundation will be. Often this step is skipped to save money, and the excavator gets the first look at what’s really underground. It’s a gamble – either it’s sufficient bearing capacity or not. If not, a Geo-tech will need to perform field evaluations to determine the solution, and depending on the soils, the costs can quickly get into the thousands.