PNW Conditioned Crawlspace VS Insulated Slab
We are a home builder in the Seattle area and I’m building a personal home. The architect isn’t a high performance architect, so that leaves me to detail some features- which I totally don’t mind.
My main question is the foundation floor systeme- I know that IF we;ll build a crawlspace it will be a conditioned, floor insulated with a rat slab, foundation walls insulated and the perimeter of the rim joist sealed with spray foam. Just like a basement. HRV for air exchange.
The only question I keep asking myself is WHY do I need a crawlspace? We will be doing ductless mini-splits the house so mechanical isn’t an issue.
Now IF I do a slab on grade with lets say R25-R30 under slab, R20 foundation wall insulation, will this be a colder floor than the non vented crawlspace approach? I do like the soling feeling of a SOG floor.
I agree with the fact that slabs are faster, more economical, and easier to detail and insulate. I just want want a colder floor assembly.
Open to suggestions and options.
Thank you all!
GBA Detail Library
A collection of one thousand construction details organized by climate and house part