Part I: How to Reduce Heating Bills with DIY Attic Insulation

Series: Installing Blown-in InsulationPermalink

Save money by adding blown-in insulation to your attic.

Our 1961 bi-level house had a reasonable amount of blown-in fiberglass insulation in the attic when we moved in. This surprised us because homes from this era often aren’t well insulated, although it’s possible a previous owner added the insulation more recently. Regardless, we were pleasantly surprised to have nearly a foot of blown-in fiberglass in our attic.

Unfortunately, even though we had nearly an R-value of 30, it wasn’t evenly distributed due to some large gaps caused by previous home improvement projects. We also had no air sealing between the attic and the conditioned rooms below, which was an even bigger issue for us.

Due to these circumstances I decided to air seal our attic and blow in additional loose fill fiberglass insulation. What followed was nearly a year of intermittent preparation, although your experience and requirements will certainly vary! I only worked in the attic when the temperature was comfortable, which severely limited the times I could get work done.

Insulation as An Investment Permalink

Outside of the fixed monthly cost of our mortgage and home insurance, the next greatest expense is heating and cooling our home. These are variable, but during the hottest and coldest months of the year we spend hundreds of dollars to make our home more comfortable to live in.

The only real way to cut these expenses is to reduce our consumption. The easy, but often uncomfortable way to do so is to lower the thermostat in the winter and raise it in the summer. The other option is to make our consumption more efficient. The latter option is preferable, just so long as you don’t sacrifice convenience and luxury.

Ideally any money spent on improving the energy efficiency of your home will generate a return on investment greater than what you could get in a traditional investment, whether it be a certificate of deposit, mutual fund, or individual stock. Do the hard labor now and reap the benefits for as long as you live in your home.

Do-It-Yourself to Save Money and Do It Right Permalink

There are two ways to add insulation in your attic. You can either hire someone to install it or you can do the work yourself. The benefits to hiring someone are their expertise and their time, not yours. Contrast that with the benefits to doing it yourself, which are saving money and doing it right, without cutting corners.

One of the reasons I decided that we’d install our own blown-in insulation is that whomever updated the kitchen for the previous owner left a mess in the attic. The exhaust duct for the kitchen range wasn’t secured to the roof vent, fiberglass insulation was either compressed or strewed about, and there was a surprising amount of construction garbage consisting of old wiring, drywall pieces, and scrap lumber. This is consistent with my experiences in hiring people to do work you could do yourself.

When you do it yourself the only thing you are spending outside of money is your time. Although I value my time, I also enjoy learning new things and have a strong preference for doing a good job, which isn’t guaranteed when you hire a contractor. Blowing in loose fill fiberglass insulation isn’t a technically difficult task. Any competent adult can do it after reading a handful of blog posts and watching some YouTube videos.

On the Importance of Air Sealing Permalink

The big prerequisite to adding insulation to an attic is to air seal the plane that separates the attic from the floor below. This is definitely a task that a contractor would either do poorly (or not at all) or charge an amount that would skew the economics of the project such that it wouldn’t be practical any longer from a financial perspective.

Air sealing is important because it prevents conditioned air from leaving the envelope of your house. It’s just like when your parents yelled at you as a child to close the door to stop heating (or cooling) the outside. There are so many avenues that air can escape the rooms of your house and exit through your attic.

The most arduous work around insulating an attic is air sealing, which is why it would likely be prohibitively expensive to have a professional do it. I spent considerably more time air sealing my attic than I did actually blowing in the insulation. I’m also convinced that I did a better job than anyone I’d hire because I had the luxury of time to do the work.

If you don’t air seal your attic then any insulation you add is for naught as you’ll be missing one half of the equation. Conditioned air will still escape through your insulation and you likely won’t see much a benefit from the added r-value. It’s imperative that you do a good job and seal all the gaps between your attic and top-floor.

How to Pick between Fiberglass and Cellulose Permalink

There are two common options for adding blown-in insulation to an attic: fiberglass, which is made from glass, and cellulose, which is recycled cardboard. There are pros and cons to each material that you’ll need to weigh before you decide which one to use. They’re both relatively inexpensive, easy to install, and do a good job of insulating. That’s where the similarities end.

Here are a couple links to help you decide which is best for you:

I decided to go with fiberglass primarily because it was easier to transport and roughly the same cost as the equivalent R-value of cellulose. I bought thirty-one bags of loose fill fiberglass and would have needed more than one hundred bags of cellulose. Since I don’t own a truck or van I had to rent a vehicle to bring the bags home. It seemed a lot less of a hassle to buy the fiberglass due to my transportation constraints.

Common Sense about Prices Permalink

For a few months previous to purchasing the loose fill fiberglass I monitored prices between several big box stores in my area. One thing that surprised me (but probably shouldn’t have), is that prices can really vary between stores and timeframes. Whether the fluctuations in price are due to promotions, the season, or local supply and demand, I cannot say.

The greatest weekly increase that I noticed was $5 per bag at my nearest store, which would have really extended the payback period for the project had I purchased my insulation then. Thankfully that price was later reduced to its earlier amount one week later, so it literally pays to be patient and buy when the price is right.

Be sure to get the bulk discount if it’s available and makes sense for your project. Some stores will throw in the blower rental for free too once a certain threshold of bags is met. I elected to buy the fiberglass insulation that I needed ahead of time due to a sale price, but do what works for you. I still didn’t get the best deal either, although it was far from the worst deal too.

The Expense Report Permalink

We spent nearly $800 on the bags of fiberglass insulation, the blower rental, and the vehicle rental. There was an extra ~$750 worth of expenses on materials for air sealing, which largely consisted of cans of spray foam insulation, boards of rigid foam insulation, tubes of silicone caulk, and plastic ventilation baffles (among many other ancillary items). Really it was a lot of small expenses that in the aggregate added up to a significant sum.

In spite of the cost, I am confident that we’ll make our money back in reduced utility bills, although it won’t be in the near term. We’ll also be more comfortable in our home, which is something that’s not worth putting a monetary value on. With every investment we make in the efficiency of our home we further extend the payback period of previous investments of time and money.

One Winter Down, Many More to Go Permalink

As of Spring of 2017 we’ve had one heating season with an air sealed and well insulated attic. There has been a significant decline in the amount of natural gas we consumed in comparison with the previous winter. This is evidenced by the month of November when we used the exact same volume of natural gas, in spite of temperatures that were thirteen percent colder than the same period the previous year.

Year-over-year change in natural gas usage with accompanying change in average daily temperature.
Period CCF Usage YOY Avg Daily Temp YOY
October -60.0% 6.2%
November 0.0% -13.5%
December -11.6% -10.4%
January -44.3% 40.4%
February -18.2% -1.4%
March -37.9% 13.9%

To my knowledge, our usage patterns are largely the same year-over-year in that we use a smart thermostat and are able to intelligently schedule when our furnace is in use. We set our thermostat at 67° when we’re home and 50° when we’re away. Only on the coldest days does the temperature inside the house get near that lower threshold, so it’s rare that the furnace kicks on when we’re away.

Was it Worth It? An Unequivocal Yes. Permalink

The winter of 2015-2016 had historically low prices for natural gas, so even though we consumed a lesser volume of natural gas, our bills look largely the same as they did the previous year. That’s okay since we are still paying less money than we would have had we not invested time, energy, and money into improving the insulation in our home. Real Gospodina and I see this as a hedge for future uncertainty, whether that be for the price of natural gas, our employment (or potential lack thereof), or the size of our family, which will hopefully increase in the coming years.

The work itself wasn’t so difficult either, although you’ll need to decide for yourself which tasks are worth doing. Some are mundane, while others can be downright uncomfortable. Regardless, there are many other folks out there who have successfully tackled this project, so you’d be in good company if you were to give it a go!

Other Good Blog Posts about DIY Blown-in Insulation Permalink

Read through those posts for further information and inspiration for your own DIY blown-in insulation project! Also if you have any good links to other DIY resources please let me know and I will add them to the list!

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