Basement Finish/installation

ddave23

We are in the process of finishing our basement and we had some questions in regards to insulation.

Our basement is a walk-out basement, the 2x6 wall (non-concrete) is located in the back of house. I noticed that when we purchased the house built 5 years ago, the insulation on this wall was fiberglass unfaced batts with no vapor. I recently removed the unfaced batts for running electrical (we have permits) and noticed that the outside wall wood under the batts was moist/wet in some areas.

It appears the entire wall (walk-out basement wall) is in the same condition, i think mold may be in some areas, as there are some black smudges. There appears to be no plumbing leaks, no outside holes, etc?

What would be the proper way to insulate this type of wall? What could be causing the 2x6 walls to get moisture?

Thank You

gregzoll

You won't be able to, until you stop the water intrusion from outside. That means checking gutters and downspouts, slope of earth to push water away. The best way of insulating, is XPS, not fiberglass batts.

__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
: Now listen, Cadet. I've got a job for you. See this button?
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
: Don't touch it! It's the History Eraser button, you fool!
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
: So what'll happen?
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
: That's just it. We don't know. Maybe something bad, maybe something good. I guess we'll never know, 'cause you're going to guard it. You won't touch it, will you?

kmachn

The moisture is likely a result of condensation. Do a Google search for "Basement Insulation Systems" and the first .pdf file is one you want to review. My understanding is that this article primarily deals with concrete walls and not an exterior wood framed wall. Nometheless, I think it will be helpful. Personally, I would probably avoid fiberglass unless you can maybe install 2-inch XPS or 2-inch polyiso (directly against plywood), then follow that up with 3.5 inches fiberglass batts. That may not work either, but it's a starting point. Oh yeah, usually best to stay away from vapor barrier. That article does a nice job summarizing the why.

gregzoll

Google will return fud. The best info is the building science website at http://www.buildingscience.com

There is no way to tell that it is condensation, unless they place plastic wrap taped against the foundation. Due to the fiberglass was damp on the concrete side, that right there tells you that there was water intrusion from the outside.

__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
: Now listen, Cadet. I've got a job for you. See this button?
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
: Don't touch it! It's the History Eraser button, you fool!
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
: So what'll happen?
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
: That's just it. We don't know. Maybe something bad, maybe something good. I guess we'll never know, 'cause you're going to guard it. You won't touch it, will you?

ddave23

Thank you both for the links...I will check them out.

The wall that is getting wet is the outside wood siding wall (basement walk-out wall). When i remove the unfaced batts, the wood is wet.

We have checked gutters and slope on the outside, and have not noticed any thing out of norm...I was wondering if it was condensation?

kmachn

The .pdf that is the first result on "Basement Insulation Systems" on a Google search is from the Building Science Corporation. Maybe it would be easier to just link to the article... http://www.eere.energy.gov/buildings...s/db/35017.pdf

It is true that one can not be sure that it is condensation. My understanding from the original post is that there is "no concrete", meaning it is an exterior, wood-framed basement wall for the walkout basement. Unless they put dirt directly against this wood wall (which is unlikely) then it is probably not water intrusion from a ground source or water runoff. However, it is possible that it could be rain water penetrating the plywood sheathing. Condensation can accumulate on the plywood side of this wall since it doesn't have a vapor barrier. It is possible that it could be the surface where the cold outside air would meet the warm inside air.

Gary in WA

Do you have vented cladding or insulating sheathing on the exterior wall?

Sounds like you only have unfaced f.g. batt insulation without the required vapor retarder facing paper with high humidity in the basement. Your Zone 5 requires it, unless as I said above.
High basement humidity or other can cause the wetting, reducing the insulation by 60-70%: http://www.nrc-cnrc.gc.ca/eng/ibp/ir...ling-heat.html

Gary

__________________

ddave23

Thank you for the info...good stuff..

I think the basement does have high humidity, I am in the process of getting a de-humidifier. I do not believe it is a water issue from the outside, but I cannot be for sure.

It may be moisture from the concrete floor, as on the same wall, past the floor joists, when i remove the insulation, I do not see any mold or does not appear/feel wet. The moist wood only seems to be the above grade walls in the basement. i can see the first floor wall (same wall above the joist) is not wet/mold.

gregzoll

First step is to get everything off of the walls, so that the dehumidifier can do its initial job. Then when you go to finish, make sure that the hvac system is properly ducted to help keep the space conditioned. If done correctly, there should be no degree difference between the finished basement space and the main living space.

While you are at it, get a humidistat to monitor the space. You can get remote sender units, so that you can read it from the main floor.

__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
: Now listen, Cadet. I've got a job for you. See this button?
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
: Don't touch it! It's the History Eraser button, you fool!
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
: So what'll happen?
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
: That's just it. We don't know. Maybe something bad, maybe something good. I guess we'll never know, 'cause you're going to guard it. You won't touch it, will you?