Attic Insulation – How to Determine Current R-Value

Good question. First off, there is no "code" requirement that would mandate adding insulation to a 6 year old house. The current standard in new construction is to try to achieve a R-42 in attic spaces. Adding more insulation to your R30 is not a bad idea, however I have a few questions for you. What kind of insulation do you currently have installed there now? What are the dimensions of the space and style of house and source of heat and A/C.

Adding more insulation is almost always a good long term investment, but before I would trust a sales pitch from a door to door vendor, I would investigate alternate routes. If a DIY project, costs to simply add a layer of R 13 or R19/23 fiber glass blanket over my existing insulation.(assuming it is also F/G blanket style). I would also seek quotes from a couple of reputable energy conservation/insulation contractors in your area. A good contractor will ask you the same questions I have, and ask about your energy costs now, then calculate the potential energy reductions in hard numbers or percentages and expected pay back period. Some energy audits are offered at a reasonable fee or even free and address several aspects of comprehensive energy savings in the home. It can be amazing what a little caulking, joist/wrap box insulation, weather stripping, hot water conservation methods and increased attic insulation can make in your total energy picture. Does your state require a professional license or certification for this kind of work? Be cautious and seek a trusted professional opinion.

Actually it is quite simple.

1. Take your dimensions of the area to be covered. Example: 25 feet X 20 feet = 500 square feet.

2. Determine what kind of insulation you are going to use. Fiberglass blanket, blow in cellulose, etc. Blanket is easy, select the R-value type you need, look on the package for how much area it covers. Example; a package covers 88 sq ft. (typical). Divide the area to be covered by the amount in a package 500 / 88 = 5.68 or 6 packs.

   You may have to double the amount if you want to double the r-value of the product. Example: two layers of R-22 give you R-44. (R-40 and above recommended for attics)

3. If you are considering blown-in cellulose, consult the chart on the bag to determine the amount needed for the R-value you want to achieve. The chart will have amount per square foot factors you need to determine how many bales it will take for your area.

4. Use "Propervent" panels, the air flow baffles you asked about, only if you have vented soffits and either a ridge vent or gable end vents. These must be installed before you add the insulation. They simply rest down on the soffit vents and staple between the rafters.

There are no special tools required to install blanket insulation. A good utility knife, blades, straight edge, dust mask, eye protection and maybe a cheap tyvec bunny suit. If you are considering blow in, you can rent the machine at many places including Lowes or HD for around $25 or less if you buy enough insulation from them.

If you give me the exact specs and dimensions you want, I can calculate the material list for you.