I am not a builder by trade but I am building my own house & shop on the outskirts of the Phoenix metro area (two separate structures). I am going to be backfilling soon so figured I better get some input on waterproofing.
Both buildings are dug into a hillside in a daylight / walkout fashion. They are constructed of Rastra which is an ICF type product.
Obviously, since we are in the desert, ground water is not really an issue. We do get some tremendous monsoon weather and some winter rains, but that rarely soaks in more than a few inches. With that in mind, waterproofing is probably unnecessary. But much cheaper to do now than wish later.
My plan is to coat the exterior with a smooth coat of stucco. Then apply waterproofing material of choice. A perforated foundation drain is in place. Site drainage will divert runoff away from the uphill side of the buildings.
So now to open the can of worms… what products do folks recommend considering the local climate. Is rolled/sprayed on asphault based adequate? What is the price premium for one of the membrane products? No matter what the product, do they need some sort of protection during backfill?
Thanks in advance.
-dch
Replies
Daen,
If it is really as dry as you say, asphaltum applied over the cured parge coat should be all you need. Rastra is very stable, so the parge won't tend to have large cracks. However, if any significant water gets past the parge coat, the Rastra matrix is very open, so it will move freely inside the wall.
If in doubt, a membrane system will give good peace of mind, and you won't need the parging, just the membrane.
A drain mat on the outside of the membrane provides some protection against backfill damage and also gives any groundwater a path to the perimeter drain.
Bill
Thanks Bill. So you suggest skipping the stucco coat and put the membrane directly on the Rastra, but also adding the drain plane product.
I'll have to look into the cost of the products. The cost of the Stucco is probably going to run $500 to $800.
Thanks,
Daen
I used a super seal membrane on my Polysteel ICF - up here in Northern Nevada we get some of your AZ monsoons and a little more snow ;)It is ugly though, a daylight basement would definitely need a transition to something more aesthetic above grade.