Sealing your insulation box.

When I began building my home near Lexington, SC, I became a certified green professional through NAHB. One of the statements that stuck with me when I took one of my green training courses was one that went "insulation does a better job when it's sealed on six sides." It turned out to be incredibly true, and one of the first thing to look for when you are inspecting your insulation package. What the rule says is this: your insulation needs to be sealed up in a box on all sides. In the wall the box would be made up of the studs on each side, the top plate and the bottom plate, the drywall on the inside, and the sheathing on the outside. Six sides. Usually that happens naturally inside a wall cavity, so you need to look other places to look for it also. Places like knee walls in the bonus room, or wall height changes inside your structure's attic. If you see unfaced insulation that's pink or yellow or whatever color it may be, you realize that as the air moves across it it also can move through it. And if air moves through it it can't do its job. Those of you that are more experienced with construction will begin to think of other places that this may be happening. Floors of bonus rooms. Walls where the upstairs is next to the attic. One solution is to switch to foam insulation that seals the holes in the cavities where it is installed. I like foam insulation, but it costs more than fiberglass batts. You can make the batts work just as well by sealing up that last side with foamboard, or thermoply, or another material. I did my whole house this way by sealing the floors up with drywall over the garage (my garage was under the house,) and putting plywood down over the batts in my attic. That won't work for every design, but the key is to use the solution that works for your situation. In another post we'll explore sealing behind your factory fireplaces and tub units on an outside wall.