No matter what kind of insulation you currently have in your attic, one quick way to determine if you need more is to look across the span of your attic. If your insulation is just level with or below your attic joists (i.e., you can easily see your wooden joists), you need to add more. If you cannot see any of the attic joists because the insulation is well above them, you probably have enough and adding more may not be cost-effective. It is important that the insulation be evenly distributed with no low spots; sometimes there is enough insulation in the middle of the attic and very little along the eaves.
Attic insulation prevents the heat in your attic, which can rise in the summertime Texas heat to more than 160 to 180 degrees, from reaching the wooden joists running across your ceilings and the studs in the walls. Wood is a conductor of heat and any exposed wood will carry this heat onto your ceiling and down inside your walls. The infrared image below was taken with a thermal camera and shows how much heat is being transferred into this room via the ceiling joists. The wooden joists are heating up this ceiling just like the heating coil in an oven. Not covering these joists up is like leaving your oven on all summer long with the door open.
Insulation levels are specified by R-Value. R-Value is a measure of insulation's ability to resist heat flow. The higher the R-Value, the better the thermal performance of the insulation. The recommended level for most attics is to insulate to R-38, 10 to 14 inches, up to R-60, 20 to 24 inches, depending on insulation type.
When adding additional insulation, you do not have to use the same type of insulation that currently exists in your attic. We blow loose CertainTeed unbounded fiberglass fill over the top of the existing fiberglass batts or blankets.
Yes, there is a 10% Federal Government Tax Credit that ends December 31, 2013. Click here for insulation rebate information.