Is a drainage mat needed on crawlspace walls?
I’m researching dampproofing products for a 41 inch poured stemwall for a crawlspace (new construction). This is a foundation set into a sloping hillside, in rainy Oregon.
I’m already planning the following:
-foundation drains – 4 inch pvc with holes down, set on gravel
-gravel backfill protected by landscape fabric
-backfill adequately sloped away from house
-a capillary break (UGL DryLok paint) on the footings to prevent moisture wicking up into stemwall.
So the product I’m eyeing is asphalt (Henry Non-Fibered Asphalt Emulsion Dampproofing 788), which I intend to roll or brush on. I’ll do two coats, and make sure the result is as thick as advised (60 mil or 1/16 inch).
My question is–should I add a protective board or drain board after the asphalt? Or just wait for it to dry and then backfill?
The fact that there IS a product called protective board makes me think that the asphalt might be damaged by the backfilling process (is that true?)
The other product that the store mentioned to me is ‘aqua drain’.
My friend who seems to know these things says that if you expect a lot of hydrostatic pressure, the aquadrain/dimpleboard may be useful.
I guess I’m just wondering
1)If the asphalt layer needs protection
2)Are there other ways to protect it?
3) How to determine if my situation calls for the aquadrain product in addition to the asphalt. (maybe just on the uphill side of the house?)
4)If I do install the aquadrain/dimpleboard product, any tips on how? The information sheet says washerhead fasteners or construction adhesive. I’m wondering what adhesive would hold it up.
5)or is aquadrain or the similar products overkill for a crawlspace on a small house? The videos I’m watching seem to be doing this for basements that need to stay totally dry. I want a dry crawlspace but…
Thank you in advance!
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