Take a 16 unit ground-up in Tacoma in 2021 where the developer already owns the dirt. The math works, but only barely. Soft costs run about 28k per door all in, architect, geotech, civil, permits, the whole pile, and on a 12 unit that same number is a reason to walk. What saves a project like that is a construction loan at a spread that does not destroy the yield on cost, and finding it usually means going through three lenders. The 30 to 40 number people throw around holds up reasonably well, and the reason is that below 20 doors you have almost no room for a cost overrun before the deal is underwater on a refi or sale. If you are not controlling land basis, 12 units in a mid-size PNW market is a very hard ask.