Basement Wall Frosting

Fast Fred

I am currently finishing my basement. I live in Northern WI so the temps this time of the year get "COLD".

I have my basement framed and insulated. I built 2 X 4 walls and have insulated them with R13. I insulated the wall and after a few days I began to insulate them. I was suprised to find "FROST" on the back side of the insulation, which was against the concrete wall. I went ahead and placed 4 mil poly on the interior framed wall.

My question is whether or not the frost is a concern? Was it a result of not having the vapor bear on the wall? I assume the tempture difference between the heated basement and the cool concrete wall caused the frost...... but I am now questioning my thoughts. HELP!

scaryjerry

It might be more ideal to use a celotex type insulation. between the block/concrete wall and your framing

You really dont want moisture trapped in with the insulation. Mold will thrive on it and you could get yourself into a bad situation.

Mike Finley

Ridgid foam insulation between the basement wall and the 2x4 studs.

safaridog

frost on basement walls is definitly a humidity(moisture problem) and can be caused by inadequite drainage. Wicking is how it gets through,when it gets cold the moisture expands and pushes its way through. I believe that proper drainage outside is the most important, sealing infiltration points at the sill or wherever else air can get in is important inside, as well damproofing is recommended to seal the wall inside as well. frost will cause damage and create pitting on your wall, repair these first with hydraulic cement and then damproof. Ignoring the problem and hoping that a vapour barrier and extra heat or different insulation will cure it is asking for big trouble as well expensive repairs and wasted materials. Look for your leakage points first and then seal them,next damproof and this should cure your problem. I feel that mould will grow on the rigid insulation so this is a bandaid and not a cure.
If anyone has extra experience to help here please chip in.

bergenbldr

Rip the fiberglass out and install the rigid foam insulation ,idealy this should run continous behind the framed walls,i have had good results with dampproofing basement walls with drylock and then glueing 1" tuff-r the (stuff with the foil facing)to wall. You might want to use 2" tuff-r this will give you r-15 insulation. As for wood framing in basement i prefer to use metal studs/track ,however if you use untreated wood you must not place it in direct contact with masonary/concrete.

redwing510

Living here in Upper Michigan, I've done quite a few basements. There are a few ways to go. I normally like to use 2" rigid that has 1x2's built into it for finish wall. Another way is to use 2" metal Z-channel available at any drywall/metal stud supplier. But the rigid is the way to go. But sometimes you may have an older basement with cmu walls that aren't very plumb, then I would use either metal studes or wood studs with the bottom plate being pressure treated with fiberglass insulation but leave at least a 1" gap between back of insulation and cmu wall. I also normally use a vapor barrier on the heated side of the wall. Actually your cmu wall shouldn't be all that cold under the 42" frost line. I'm assuming you don't have a leaakage problem in your basement currently. The use of a drylok product before wall assembly would also be a good idea. Just a little Finnish food for thought!

mjay

Use a hair dryer, heat gun, something to dry a section of wall. Use duct tape to tighly seal a piece of aliminium foil to basement walls, after 24/48hrs
If the outside of the foil is wet, you got condensation; if the side of the foil against the wall is wet, you got seepage.
Check gutters, downspouts, siding, grading etc: Look for reasons that water may not be draining away from foundations.
How old is the house? Was the exterior waterproofed? What drainage is underground? Is the house at the bottom of hill?


Rigid insulation is the way to go. Take out the fibreglass and vapor barrier: Vapor barries trap moisture and will create a breeding groud for rot and mold in wall cavities. This will not only damage walls [masonary and wood], but also unhealthy air quality. And never carpet a basement.
www.buildingscience.com is a good start for info also Fine Homebuilding 169 March 2005 has a great article, check your local library.
Good luck with the project

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RowdyRed94

While moisture may indeed be coming from outside, the vast majority of frost and mold problems originate inside. Heating, human emmision of vapor, bathrooms and cooking result in large amounts of humidity. Positive pressure forces it outward, often resulting in rotten wall sheathing and mold which is often attributed to leaky windows, etc. It's not.

While you might take the advice given here and use rigid foam, your best bet might be to use nothing at all. Minnesota's upcoming building code changes allow remodelers to skip insulation altogether in existing basements because so many problems originate from moisture. Whatever you do, don't add a second vapor retarder which will trap moisture. Allow it to evaporate into the building and install or utilize proper mechanical ventilation down there.

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mjay

1st.Determine the source of the excess moisture: Interior or Exterior
2nd.Solve that problem.
3rd. Insulate with rigid foam: It's semipermeable and won't trap moisture, it will thermally protect the basement, and break the contact between framing and concrete. This moisture will diffuse into the air, use an A/C or a dehumidifier to remove excess moisture.

Yep. Trapped moisture = Decay + Mold Therefore no Vapour Barriers/Retarders

Skipping insulation? Makes no sense if you want a useable area, unless of course your using it for a walk in fridge.

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