Insulation

[gouyangg]

Can anyone tell me whether I can use R-19 Faced Fiber Glass Insulation (6 1/4"T x 23"W x 94"L) for 2 x 4 stud walls? It is intended for 2 x 6 exterior walls.

Thanks in advance!

[Rich]

You can try and stuff it in there. It won't work as efficiently as it should because it's over compressed.

[N2Deep]

You could also use the expanding spray in insulation - it seals and expands into that cavity. High R value due to sealing the air out - check out Icynene brand.
I hear lots of good things about it.

[Rich]

Just a pain to shear off after it hardens.. haha. Little fluff flying everywhere. Have a shop-vac ready. Typically only used for new construction also - putting it into a closed wall cavity could pup a few nails. same goes for around the windows and doors - get low expansion foam for there. Causes your windows and doors to bind up.

[Sophist]

Hi

First off yes it is ment for a 2x6 wall.

If you want to get an R19 out of a 2x4 wall you can ether stuff it in there and loose some of the efficiency like rich mentioned or you can use r 12 in the wall and a layer of rigid foam insulation on the inside to boost your overall value.

The first method would be cheaper and the loss in efficency wouldn't be to much.

What does your local code say for a minimum R rating for walls? This might be what determine which route you take.

The first method mentioned above wouldn't meet the code I would bet but the second method would if you used 2" foam.