Insulate — you know you should do it; but how much insulation do you really need? You can check the building codes in your area to find out how much insulation is being put in new construction. Here in the Northeast, new homes are insulated to R-19 and attics to R-38. What does the R-factor mean? It’s the insulation’s resistance to heat flow. In another words, how much heat it prevents from escaping. The higher the R-value, the greater the insulating power.
How much do you need?
If you’re insulating an area of your home that has no insulation, you want to know what thickness and width of insulation you need. Check whether your home has 2 x 4s or 2 x 6s — that’s the size of the wooden studs in your walls and joists in your ceiling. Older homes generally have 2 x 4s, while most newer construction uses 2 x 6s. With 2 x 4 studs, the depth available for insulation is about 3 1/2″ which is equal to an R -11 or R -13. You might think that more would be better and why not use a thicker insulation in the same space, but it doesn’t work that way. By compressing the material, you can actually decrease the ability of the insulation to do its job.
The width of insulation you need is determined by measuring the distance from the center of one stud or joist to the other, usually 16″ or 24″ on center. The final measurement is the total square footage of the area you’re going to be insulating.
Faced and unfaced
There are two kinds of insulation you could use in your home. Kraft faced insulation comes with a vapor barrier that looks like a sheet of paper on one side. You install it by stapling it to your walls or ceiling with the vapor barrier toward the heated room. If you’re increasing the insulation in an area that already has some existing insulation with a vapor barrier, you want to use unfaced insulation. In this case, you don’t need a second vapor barrier.
Batts or Mini-rolls
Insulation comes in either batts or mini-rolls. A batt is a bundle of usually five individual pieces of insulation cut to a standard 94″ which is the height of most walls. The mini-roll is one continuous piece of insulation in various lengths, up to 40 linear feet. This allows you to cut the insulation to whatever length you need for parts of walls or odd sized areas.
The single greatest loss of heat in a home is through the attic. Attics should have an R-38 value. Most homes ten years or older have a maximum around R-19. One of the easiest ways to add insulation to your attic is to have a professional come in and “blow-in” fiberglass insulation under high pressure. It takes only a couple of hours to blow in enough fiberglass insulation to increase an attic from R-19 to R-38. The advantage of blown-in insulation is that the high pressure forces the material into all the little nooks and crevices making it very well insulated.
Adding or increasing insulation is a cost effective way to make your home more comfortable and is the most energy efficient improvement you can make.