I am in the process of planning a detached accessory dwelling unit (DADU) in Seattle. This is on a rental property that I own. I am considering putting a basement under it. Per Seattle’s DADU rules, the basement can’t be habitable space but can be used as storage and could be a shop, etc. I think it would be useful space and if rules change in the future it could double the size of the house, but I’m not sure if it’s worth the cost. Most of my work is remodels and I don’t have a ton of excavation experience. You don’t see too many new basement foundations in Seattle, presumably because they aren’t necessary in our climate and water can be an issue. Any input from Seattle area builders out there? Am I crazy to be considering this? If not, any potential surprises I should be aware of? The DADU footprint (a house really) is 1000 sf. The lot is relatively flat with easy alley access. The soil is glacial till.
Thanks