I am about to start a basement remodel project. I have been tossing this around for a long time trying to figure out the best way to frame/insulate the walls. I live in a cold NorthEast town and have a basement that is pretty much water free. Based on research I have been doing I have been thinking about doing my walls like this:

2 inch (r10)rigid foam glued to concrete wall. Next putting up 2x3 framed stud walls, installing unfaced installation and then putting up drywall. I really don't want to cause any moisture problems since I have none right now. Will this configuration allow my walls to "breath"?

Thanks to all that can help..

Joe

 

Joe,

You seem to be doing some things that would be considered overkill and possibly cause some problems.

I would forego the rigid adhesively applied to the walls. This can cause condensation to form behind and down to the floor. As soon as the cold hits the inside with rigid, it can condensate there. Do this;

Frame your walls allowing for 1" space between wall and foundation, use 2x W/T plates, install unfaced R-13 between studs then apply 6 mil vapor barrier to warm side of room, then your wall finish.

You're done!

Hope this helps!

 

I take it that you have had good luck with this senerio. Is R13 good enough insulation?

That sounds really easy. If I leave that 1" gap, will air get back there to evaporate the water?

Is it OK if the unfaced insulation touches the wall? Can I use kraft faced insulation and forgo the VB?

Thanks for your help, This is really good info.

Thanks, Joe

 

Joe,

I guess this is the best and most economical way to construct walls that would be placed on the exterior. I prefer to see 2x4 but as mentioned by others they can get 2x3's. You still need that W/T plate. Doing the framing 16" O.C. provides a solid base for your 1/2" drywall.

The reason to keep the wood out from the walls is the moisture that could damage them. Using larger insulation like R-19 would touch the walls. I have stated before that if a homeowner did put thicker insulation in, and the wall was only 1" from the masonry surface, I recommended hanging a vapor barrier between the back of the wall and masonry surface. This doesn't allow for the insulation to touch the wall and air movement is not restricted but at least you won't create damage to the insulation or wood. If you do want to increase the R value, move the wall out further or use the R-13 and then apply a rigid insulation over the studs (warm side) then drywall (not paneling) *Code advises a 15 minute fire rated material over any rigid insulation - 1/2" Drywall* You can then put paneling over this if desired to met code.

Kraft faced insulation is fine to use in the above scenario. No need for the poly and you can do everything easily. You may find this easier and I would do this versus unfaced and vapor barrier because I don't like to play with it any more than I have to.

Let me add one other thing, rigid insulation used on a concrete/masonry surface is fine. Considerations to make in using this is;

1. If you are just using 1 1/2" rigid and furring strips - A. You need W/T strips to protect the wood. B. The strips can be adhesively applied but they must be solid - mechanical anchors may have to be used to insure that if shelving is installed it will hold. C. Any electrical boxes will have to be shallow - sometimes makes it hard to wire. D. You must use a fire retardant material over this as per Code.

(Most books, articles about rigid and furring strips fail to say anything about the use of W/T and this will get destroyed and be a good source for mold/mildew with the slightest hint of moisture)

2. Alternative which does add cost is to apply full rigid sheets to the concrete/masonry walls, adhesively applied, then place frame wall against the rigid, then insulate between studs and cover with drywall. The rigid does then act as a vapor barrier.

Hope this helps!

 

2. Alternative which does add cost is to apply full rigid sheets to the concrete/masonry walls, adhesively applied, then place frame wall against the rigid, then insulate between studs and cover with drywall. The rigid does then act as a vapor barrier.

This is what I was planning on doing. I saw it as preffered on the building sceinces Web site. I was a little concerned about moisture between the rigid sheets and the wall. I got to ask you though, If money was no object, would you do this over the 1" space as opposed to the rigid applied right to the concrete wall?

Thanks for the GREAT Info, this is really helping me..

 

Chubba,

Since you ask it like that, I would do the alternative #2. This will definitely increase your R-value and reduce some heating costs. By the way the rigid does breath so if you ever did get the slightest moisture, it would dry up.

With #2, the wood frame wall doesn't require the 1" space, you can place your wood right up against it. You may even want to install R-11 Unfaced versus R-13 Unfaced. No need for 6 mil poly either. Use W/T bottom plates and then you're in business! Don't forget to purchased some air filter maskes, wear goggles and long sleeve shirt!

Thanks for allowing us to help and Happy New Year!

 

Thanks a bunch Doug, you really helped me make this an easy decision today, I have been battling for months on this.

One last question, What type of glue is best to adhear the 2" rigid to the wall? And what kind of tape should I use to seal the joints of the rigid?

Sorry, thats 2 questions.

Thanks Again, Joe

 

Joe,

Here's 2 answers!

I would suggest Liquid Nails for projects - great for foam to masonry/concrete applications - won't take much.

I would not apply tape, don't really need it if your joints are tight. This would be different if this was on an exterior main floor but not here.

Glad these discussions have resolved months of thought. Hopefully all this will keep you warm with lower heating bills!

If you need anything, just let us know...Happy New Year!