Is Adding Attic Insulation Really Worth It? | Results from a Real House

We had insulation added to our upstairs attic in Fall 2021, and I thought it would be worthwhile to see what kind of difference it made in terms of our heating bill. Previously, the attic had (maybe) R-28 total, and we had 4"-5" of blown-in cellulose added to bring the total up to around R-46 to R-50. Using thermostat data from our ecobee from the previous winter and comparing to this past winter, I can get an idea of how much more efficient heating the house is.

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[clausiusuf]

Brilliant, thank you. R-22-28’ish to R-48ish resulted in an almost 10% improvement in efficiency (reduced heat transfer). And youecexcel skills are impressive.

[TV-xvle]

I just got quoted $15k to insulate my attic with cellulose. Told the sales guy to take a hike. Small 1300sq ft house.

[ericwotton]

Did this project myself. Took along time to air seal. Cost about $2000, I built an insulated cat walk thru the attic. Saves us about 100gallons of heating the first year.

[dolfinwriter]

I think your water heater gas consumption is absolutely relevant. Presumably, making your house leak less heat would also cause your water heater need to heat less due to lower losses.
And by all means, do a similar comparison for your cooling bill in the summer and then combine the two. I track my water use and energy use month by month, which is how I saw how dramatically we cut our water use ~2005 when we got rid of our top loading washer and got a front loader $400 off at a "scratch and dent" sale. Now I'm comparing our larger house in Kansas to the smaller house we had in California, and what my updates and improvements are doing to our energy use over time.

[jlivers]

I love this video because it shows realistic expectation from a realistic scenario. Most people aren't going to spend the time removing old insulation and air sealing. Thank you. I will say I'm hoping to have a little better efficiency as I did take the extra step to remove the old fiberglass batts, and air sealed a few big areas like light fixtures and bathroom vents and added approximately 15 inches of Greenfiber cellulose back. But again, this took a whole lot more time and effort which many people won't do, and I still feel I had several things I could have done better.

[LifeyApp]

wow, you rock for putting in so much work into this video! thanks!

[RatedCfm-czff]

I have a bungalow just under 1300 sq feet, had 8" R-20 blown fiberglass in the attic.
I added 10"-11" of cellulose to get the attic around R-50.
I also dense packed cellulose around a couple knee walls inside a frame I built around them.
What I did over a period of two years was compared all of my gas consumption.
Looking at the previous winter, then compared to the winter after.
This showed a 23% drop in natural gas consumption based on gigajoules of natural gas used for each billing period.

Cellulose is definitely better than blown fiberglass, or batts.
I've done all three in different homes, and the cellulose made the most noticeable difference.

[mroberts]

Very cool! Thanks for doing this. You are a great example of why YouTube is great.

[Dan-szgc]

What a great video. Thank you for the knowledge!

[TRMRJaZz]

Great video! As you mentioned air sealing helps a lot in my experience. For crawlspaces too.
Top plates and around vents.

[motavice]

I have previously blown in insulation in the attic about 18 inches tall at the highest points. I'm going to buy 10 bags. I borrowed a quality temperature gun from a friend and and scanned the ceiling inside the house 1ft by 1ft to get areas needing touched up.
It's triple digits here and i keep the temp at 75. Attic temp at 112 during testing.
Living room was 77-79 in most spots and highest was 83 1-2ft from edges of walls. Our dining room was half 77-79 and the other half started at 80 rising all the way to 87 as i get closer to exterior wall!! Most of kitchen 79-81.
Hallway was 78 and hallway attic stair drop was 92 at center and 85 at edges. Spare room was entirely 81. Main bedroom was 79-80. Bathroom was coldest at 72-75.
I will make a map layout of the house and draw everywhere i need to spray in/add. I also blocked off half the Bathroom vent it doesn't need to be that cold so the air will push more out the needed vents.

[jonwikan]

Well, if an air sealed R-12 stops 92% and R-48 stops 98% of heat transfer it makes sense that you had only a 9% improvement, especially without air sealing. Cellulose is nice because it does stop airflow a bit better and unlike fiberglass, cellulose retains r value as it gets colder.

[EekaMau]

Awesome work ! thanks for sharing.. How much of an improvement in your comfort while in your home during the winters / summers ?

[NOOBKILLER]

Based on all the youtube research, that heat seal would save like 20% on total home airloss just from sealing the attic.

[DonTruman]

Appreciate it. This is the first I've seen on benefits achieved through insulation. In this case it was an increase in insulation from around R-28 to around R-50. Roughly double. Not a huge benefit and sounds like the break-even point on the cost could be 20 years. Albeit if energy prices skyrocket, as they could, then the break even point would of course be sooner.

[JonLeDoux-qxi]

I added 5" of celluose with vents to my 1060 sq ft house two years ago by a local contractor (Minnesota) for a total of $1, 200.

[Jopn]

Went to home Depot rented the machine and bought the sacs and did it myself

[HonestEvolution]

Thank you for sharing you findings to the world. I’ve done the same added cellulose and added a perforated radiant barrier over the insulation. Curious to see if theres going to be a difference.

[oliverupload]

Thanks. Good video. Preparing to add insulation this weekend

[collinbradford]

Similar house, i just added R30 batts to mine by myself. Spent roughly $600.00