Zone 6 (Maine)
1. Foundation – I’ve specified 2″ XPS foam board on the exterior foundation wall. There’s also a perimeter drain. Should the foundation have a waterproofed coating applied before the XPS board is applied? Can you recommend a type/kind of WP coating?
2. Slab – I’ve specified 2″ XPS foam board, 6 mil vapor barrier and rebar stanoff’s/WWM. Gravel is specified under the slab. Is this 3/4″ gravel? Note. Contractors use a lot of gravel fill with dirt mix. It compacts (dense) well but believe it can hold moisture. Radon mitigation system is planned so 3/4″ gravel is preferred?.
Replies
Full basement, crawl space or slab on ground?
What's the surrounding terrain like?
Rain gutters in the plan? Do NOT connect them to the foundation drain(s).
The WWF used in the slab will probably be better supported by #4s on chairs (24" c/c) with the mesh on top of the bars. Ever watch a placing crew do a slab? It ain't pretty when they're walking all over the WWF.
Full Basement, Clay about 18" down, No gutters (stone will be placed under the eaves with edging and concrete FDN well above grade (splash/snow)). Yes, SOW specifies chairs. It up to them to use WWM or rebar, Waterproofing FDN before XPS?
I'm not an expert but I'm building similar specs and have read/researched a lot.
1. There is a good article floating around FHB or related groups about the difference between dampproofing and waterproofing. Quick version is you want waterproofing if there is a water pressure (like sitting in water). If your exterior perimeter drain moves the water along then maybe dampproofing is all you need. I am doing waterproofing because I needed a little, so why not just overdo the whole thing. I am using WR Meadows Mel Rol LM (liquid membrane), but you will be heavily limited by what your local supplier offers. My goal is to push the 2" XPS into the waterproofing while it is still wet, as an adhesive.
2. I'm building on hillside bedrock, so moisture is a major concern. You want 3/4-1.5" clean gravel. Some places its called #57. No fines.
I don't think you would regret spending a few more bucks for 10 mil VB.