Is adding attic insulation right for you?

Adding attic insulation is typically near or at the top of the priority list for homeowners when looking for economical ways to save on energy costs. However, depending upon your DIY skills, the number of years you plan to stay in your house, your cost for energy, and the climate in your area, and other factors, it might not have a high enough return-on-investment to make sense for you as an upgrade.
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​R-value is a rating system used for insulation that measures its degree of insulating power. Insulation typically works by preventing conductive heat flow. The “R” stands for resistance to heat flow, with higher values being better at reducing heat flow and, thus, energy savings. Insulation works in both winter and summer. In the winter, the resistance is to heat escaping the house and in summer the resistance is to heat entering the house

When inspecting homes in the Redding, Red Bluff, and Chico areas of California, what I predominately find is about 6 to 9 inches of blown-in attic insulation. This is roughly equivalent to an R-19 insulation value that was the building requirement for many years, which has increased only slightly to R-22 that is the national minimum today.

​It is important to understand that building codes are only the required minimum. The U.S. Department of Energy has done many studies assessing insulation R-values versus heating and cooling costs and has for several decades recommended anywhere from R-30 to R-60 attic insulation depending upon what U.S. climate zone the house is located. Shasta, Tehama, and Butte counties are in Climate Zone 3 that has a current recommended value of R-38 for attic insulation that is the equivalent of about 14 inches of blown insulation or about double what most houses in our area have installed.
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That is all well and good, but how much does adding attic insulation cost versus how much money will I save you ask? That is a very complicated question. It depends on how much insulation you currently have, the type of insulation you install, how much you actually use your heating/cooling, your price of energy (e.g. propane, gas, electric, wood), how long you plan to live in your house, and how handy you are to take this on as a DIY project versus the cost to use professionals. Since there are thousands of combinations to those variables, the only way to synthesize it down is to use a few scenarios and you pick which is closest to your situation.

Let’s say you have 1,500 sq.ft. house and your combined annual total energy costs (e.g. electric, gas, propane) per year is $2,500. The Department of Energy predicts that, if you live in Climate Zone 3, provided that you seal up air leaks into your house (e.g. doors, windows, attic, crawlspace), then  increasing your attic insulation from R-19 to R-38 will save you around 14% of your heating/cooling costs. If you can separate those individual costs out, then 14% is your predicted savings. However, if you are like most folks and are not able to separate just heating/cooling costs, then the Department of Energy predicts that for Climate Zone 3 such an upgrade would save 8% of your total annual household energy costs. Doing the math, 8% of $2,500 is $200 in estimated energy savings per year for our example house.

Let’s say that you are a DIY type of person and have 7 inches of blown cellulous insulation in the attic (roughly equivalent of R-20) and want to double that to 14 inches of cellulous (R-40). Cellulous and rock wool are some of the cheaper insulating materials. It will take about 30 to 40 25-lb bags of cellulous at about $12/bag for the “green” recycled-paper product, for a total of about $400 to $500 in material costs. Home Depot and Lowes both have deals that they provide a free one day rental of the machine to blow the insulation if you purchase a minimum number of bags. In this DIY scenario, the break-even point on your investment is only 2 to 3 years. If this is your lifetime home and you are handy person, the benefits versus costs are excellent. For example, 10 years of savings would equal $2,000 at current energy rates and those rates will almost inevitably increase in the future.

If the same house had fiberglass insulation, the recommendation is to add more fiberglass insulation (adding cellulose over fiberglass will compact the fiberglass and reduce it R-value). However, the cost of the materials is more expensive, most likely in the range of $600 to $900 dollars, perhaps more. In this scenario it might take 4 to 5 years to recoup your investment and if you are not sure how long you will stay in the house, perhaps the benefit versus costs will be less attractive.

If you are not the handy type or just want the professionals to handle the installation, material and labor costs might run $1,500 to $2,500 for a 1,500 sq.ft. house. In which case, the return on investment in this scenario would be 7 to 12 years. In this scenario, if you are not a DIY type nor planning to stay in the home that many years, the costs might outweigh the benefits.

These are just a few scenarios. Check your energy bills, check the insulation level in your attic, investigate current insulation costs, get quotes from contractors, and so forth.  The 8% (of the total energy use) or 14% (of just heating/cooling costs) are the best available numbers to work with for predicted energy savings in Climate Zone 3. If you live in another part of the country, please refer to following link for energy savings estimates in your area.

https://www.energystar.gov/campaign/seal_insulate/methodology