I am going to hang new drywall in my kitchen. One of the walls is on the perimeter of the house so I figured I should re-insulate as well. I was recommended to get at least R-18 insulation given where I live. I'm looking at wall insulation sizes and I keep seeing 15 inches wide, but if studs are 16 inches apart, wouldn't this be too small? I never installed insulation before, but I would think it has to be in there pretty snug to be effective. Also, I'm not exactly sure how to determine how thick the insulation should be. Can anyone point me in the right direction as far as determining a size? Thanks.

The wall studs are typically spaced 16" on center, which means it is 16" from the center of one stud to the adjacent stud. Insulation is sized to fit this space so the 15" width would work fine. Check with the local building inspector's office and ask what R value insulation is required by code. You may be limited by the depth of the wall. Is the wall framed with 2x4's or 2x6's?

Thanks, I should have realized that. I haven't taken down the walls yet, so I am not sure what size the wall is framed with, does this affect what size insulation to use?

It sure does. You could go with a higher rated insulation for a thicker wall... like R-32... although more expensive, it is superior to R-18 for the simple fact that it is thicker. If it is a standard 2X4 wall, R-18 is what you would want to use.

Don't forget to seal the bottom of the wall well so the insulation doesn't get wet in the kitchen... wet insulation takes a long time to dry and becomes very heavy... more often than not, wet insulation needs to be replaced.

Try using green board for the walls (if you are using gypsum)... that cuts down on water damage. Also, if you are trimming the base of the wall, try plastic trim and caulk it with both a top and a bottom bead as well as in any corners.

Solid advice from epawls: just remember to wear long sleeves, gloves, eye protection and a mask when you handle the insulation. Even minimal contact with fiberglass can cause problems. Better safe than sorry...

Yea never can be too careful. The wall isn't near any water sources in the kitchen, do you still think I should use the green board?

Regular drywall will be fine in the kitchen.
GOOD LUCK,AC

AC is right, regular drywall should be OK. If you are only taking down a part of the wall, make sure you get the same thickness for the drywall you are hanging...