Doug:

I found your recent post to "bateslabel" regarding insulating and framing basement walls very informative. I to am about to tackle this job (albeit with the help of some professional carpenter friends) and hope you don't mind a couple follow-up questions to make sure I understand the proper/best technique.

I am indeed planning to use traditional 2*4 framing set at least an inch of the concrete wall (half the wall is below grade and half above). However I'm not certain from your posting if:

1) I should install a poly/plastic vapor barrier directly over the concrete wall from floor to ceiling and if so - am I suppossed to slice some "weep" holes at some level (relevent to the exterior surface grade) in one of the plastic sheets?

2) Should I make sure that the fiberglass battings do NOT touch the plastic sheeting on the concrete wall or does that not matter? I can easily make the gap between the concrete wall and studs greater then 1" to accomodate thicker insulation.

3) If I use kraft faced insulation - am I creating a double vapor barrier that could trap mosture between the drywall and the concrete wall (i.e. in the inulation)? OR is the plastic on the concrete wall considered an exterior moisture barrier while the kraft paper is the interior vapor barrier?

4) I prefer using kraft faced insulation for easier installation (stapling to studs) but in previous high humidity areas (e.g. bathrooms) have felt poly was better so I put many slices through the kraft paper after instaling the insulation and then installed poly over the kraft faced insulation (under the drywall). I was told that slicing the kraft paper eliminated the double barrier (trapped moisture) concern - Do you feel this an acceptable technique?

Note: I do not want to use foam insulation because this house had termites in the past (about 20 years ago) and even though there is no sign of recent activity and we've treated with Termidor to be safe - I've heard they love to travel through foam insulation - so I don't want to provide any potential pathways. Speaking of which should I use treated studs for more than just the bottom plate or is that overkill? I dont think my carpenter buddies like steel studs.

Thanks in adance for your advice!

Ed
Chicago, IL

 

Ed,

Thanks for the compliment!

Here goes...

1. Yes, you have it correct. Slices in all sheets at grade level. Poly needs to be overlapped and not be sealed/taped.

2. We want to make sure that the insulation doesn't touch the wall. Having placed poly there is fine but I like to see the poly hanging and NOT being touched by the insulation as you want the poly to just hang...this provides some "breathable space" between poly and concrete.

3. Bear in mind, the slices in the poly are creating a weeping effect, there is no worry about trapping moisture. This is, in part, the breathable space I mentioned above. The latter part of your statement is true..in a sense. Also note that we are not and you would not be able to make an air-tight environment with the use of the poly and kraft paper barriers. If that was the case, you realize that I would not even suggest this nor would the State of Minnesota require it. Thus we are not trapping moisture that could potentially be a problem.

4. The need to put slices in the kraft paper is not needed. This is not like a bathroom, small, enclosed with extreme moisture content when in use. In the basement, you can use kraft faced and staple it to the studs. No need for vapor barrier over this (between studs and drywall). If installed as I explained, it will be fine.

If termites were or are an issue, then they should be terminated! What you have done is good and it should work well. I feel if a home is sealed properly, the need to use W/T all over is overkill. You know your home better than I and you must decide if this is required.

Hope this helps!

 

Hey Doug,
When finishing off the basement, I placed wood studs (pressure treated) on the bottom a inch away from the wall, insulation, and plastic as an extra vapor barrier before putting up the drywall.
However, I have nothing between the concrete wall and the insulation and it maybe possible that the insulation is touching the wall. Is this a potential problem and if so what can I do at this point to correct this matter. Thanks for the help.

 

ecd123,

If you have provided a good vapor barrier of poly, between the drywall and studs and if SOME insulation is touching the concrete walls, chances of damage would be minimal. If you installed 2x4 walls then R-13 should had been used to keep it off the concrete but if you installed thicker insulation, then I would say that yes. This would be a problem if you have any heat loss, that gets bewteen the space, the temp difference as this touches the cold concrete could cause problems.

You be the judge of what you have but my thoughts are it should be OK.

Hope this helps!

 

It took me a while to get back to the post - but thanks for your detailed reply!

Ed

 

Ed,

You're welcome!

Hope it all helped!