Basement subfloor vapor barrier
BG57Builder
| Posted in General Questions on
While drilling holes for tapcons in basement for baseplate I drilled too far and went all the way through and likely punctured vapor barrier underneath. I did this probably 30 times without really thinking.
How big of an issue is this? Worried about moisture or radon penetration now.
Thinking I’m going to take the tapcons out, fill hole with silicon and put tapcon back in. Is this an adequate solution or is there a bigger issue on hand?
Zone 5A
Nervous I messed up bad.
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Replies
It's not a big issue unless you need that vapor barrier to also block bulk water. Vapor barriers still work if they have some holes or tears in them (within reason), they aren't the same as air barriers that really need to be well sealed in order to work properly.
I wouldn't worry about what are probably 30 or so 1/4" or smaller holes here. If you're really concerned, inject some polyurethane sealant into the holes before inserting the tapcon. The sealant will squish around everything as the tapcon acts like a piston during installation, and the sealant will help to seal any holes that might otherwise be potential leaky spots.
Bill
Thank you for the response!
I am concerned about the hole in poly matching up directly with hole in concrete, creating an easy passage way for moisture/radon.
If I do put some silicon at the bottom of the hole before putting tapcons back, should I let it cure for a night first? Or best to put it back in right away?
Thank you again, I am nervous I made a big mistake
I would prefer polyurethane over silicone for this (note that "silicone" is caulk, "silicon" is the element).
You would NOT NOT NOT wait for the sealant to cure first. You want the sealant to squish around the fastener and seal everything -- the hole in the poly, the poly to the concrete, the tapcon to the concrete, maybe even your pants to the concrete! :-D The sealant will cure fine after you put the fastner in, and it doing it that way ensures the seal is good and the hole is plugged.
I wouldn't really worry too much about the vapor barrier part, but it is standard practice to seal cracks and things if you're concerned about radon, so it's probably worth doing if that's the concern. A tube of polyurethane sealant is cheap and readily available, and sealing the holes in the way I describe will only take 10-15 minutes for the entire floor. The sealant sets slowly enough that you could inject a row of holes with sealant, then install that row's fastners, then move on to the next row. That's probably more efficient than doing each fastener one by one, individually.
Bill
I already bought the silicon - is there a major reason why use polyurethane over silicon? Am I fine using silicon?
Silicone is OK too, it's just not as durable as polyurethane in this application.
Bill
BG,
From a moisture perspective it's fine. Unlike water and air-barriers, vapour-barriers are effective based on the percentage of area they cover. Incidental holes or gaps don't matter.
Whether radon is an issue can only be determined by testing - and remediation relies on depressurizing the area under the slab. Again I doubt the holes make much difference - and I doubt they are the largest gaps in your poly.
Thank you for the response!
My concern is that a hole in the poly matches up directly with a hole in the concrete, creating an easily penetrable passageway. A random hole in the poly from before pouring concrete isn't going to have a drill hole directly above it.
Rather concerned I made a big mistake
BG,
A pasageway for what though?
If the concern is bulk water below the slab, poly probably won't be very effective keeping it out anyway - and as concrete is porous, whether it lines up or not makes no difference.
If the concern is water-vapour, the incidental holes make no difference.
Radon moves though concrete quite readily, so whether the holes line up again doesn't matter.
You haven't made a big mistake. Your sub-slab poly is probably in much the same shape as that in the average new house - and I doubt survived the installation of the slab when built without holes and gaps.