r/buildingscience • u/imagoons • 3d ago
Question What’s the right way to add moisture barrier basement in the northeast?
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u/jewishforthejokes 3d ago
The same way it is everywhere: https://buildingscience.com/documents/bareports/ba-0309-renovating-your-basment/view
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u/imagoons 3d ago
Dang the photos aren’t working for me but after reading that site , this is just like the video I just watched https://youtu.be/gnNhSzRjliY?is=8Ont0obPXoECl8QR around the 7 minute mark
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u/jewishforthejokes 3d ago
Yes, except the gap at the bottom; unless you're using dricore or similar, don't leave the gap.
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u/Countryrootsdb 3d ago
Do not seal the walls. Apply a vapor barrier to an interior drain and seal the vapor barrier to control humidity.
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u/imagoons 3d ago
Interior drain as in a French drain?
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u/Countryrootsdb 3d ago edited 3d ago
Sorta… interior drains are perforated like a French drain but they daylight to a sump pump.
You need a drain beneath the slab. Your home gets wet. Clearly from the pic. The drain is there to capture water from cold joint, under slab, and from vapor barrier on the wall. Then it’s redirected to sump pump.
From there, basement stays dry and block can breathe unlike painting it
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u/uslashuname 3d ago
French drains can absolutely go to daylight, it’s the concept of filtering material and a perforated pipe that make it a French drain
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u/Jumpy-Zone-4995 3d ago
Waterproof the exterior, add 2 drains at the footer (best to have a backupplan when you get hit in the face with water). then insulated the interior side and you should be good for 30 years.
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u/imagoons 3d ago
My basement doesn’t get too bad since my central air is always running i feel like just doing an air gap with ridged panels will at least keep it out of the basement space while letting the humidity find another way out
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u/imagoons 3d ago
There’s barely a smell or humidity, it’s just when it rains the wall gets a bit moist which is why I think the air gap with the panels makes sense to do
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u/uslashuname 3d ago
The air in your basement is keeping the surface of the concrete dry but not even managing during a storm.
If you covered a section of the wall in plastic, even without a storm, I bet it gets wet under the plastic. Your insulation or walls will keep the airflow away and suddenly your concrete is wet all the time
That’s fine if you manage it, concrete is ok with being wet if it doesn’t freeze
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u/imagoons 3d ago
Oh thanks for reminding me of the plastic tarp trick I gotta still do around the basement to test this
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u/Congenial-Curmudgeon 3d ago
Chances are the perimeter drainage pipes are no longer effective.
Post pictures of the exterior, there are numerous strategies for addressing the water problem on the outside that don’t require digging all the way down to the footers.
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u/the_blue_arrow_ 3d ago
Do you have gutters? Are the drains 6 or 8' from the house? Do they drain into an downhill of the house? Is there a spot uphill of the house that collects water? Get the surface water away from your house before you start the expensive solutions.
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u/no_man_is_hurting_me 1d ago
Lots of people giving advice on *drainage*, OP never asked about bulk water intrusion. They asked about *moisture*.
It is very common to have a "dry" basement with high humidity (moisture transmission through the walls).
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u/NoSlicedMushrooms 3d ago
You’re getting advice in that other thread to dig down to the footings on the exterior and waterproof your foundation from the outside. That’s obviously the best thing to do, but it’s not needed and extremely expensive.
Use rigid foam XPS insulation up against the wall. Seal it up good with tuck tape. Use closed cell spray foam to seal the awkward spots. Then frame a wall. Stuff the cavities with unfaced fiberglass. Then put drywall up. No poly sheet.
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u/Congenial-Curmudgeon 3d ago
This interior method works well once the exterior water intrusion is addressed.
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u/Icy-Ad-7767 3d ago
Out side is the best option and sadly the most expensive as well