The long anticipated, eagerly awaited day finally came today. I’m talking about insulating our attic. Finally did that. Never want to do it again. Last fall I purchased 76 bags of cellulose insulation at Lowes. It sat in the basement for a year, with several bags getting ruined in a flood last spring. At the time, I was involved in a major project that included a lot of travel to Florida, so my time at home was spent with my family instead of working on the house.
This year was different. The weather today was perfect, not too hot, not too cold, so I had no more excuses. Last weekend I crawled around in the attic stapling up the rafter spacers I placed in the soffits. These provide a gap between the installation and the roof sheathing allowing air to flow up to the ridge vent. I noticed that the attic was much cooler today than it would have been before I opened up the soffits.
I did a fair amount of research on this and found that blown cellulose insulation is a good product. I did not want to roll out more fiberglass because the pitch on our roof is pretty shallow, and it would be almost impossible to get it under the very narrow part of our roof.
I found I was right when I stapled the rafter spacers last weekend. There were some areas that I had a real hard time getting to. Lowes has a pretty good How To Library on home insulation, R-values, etc.
My friend Dan and I headed off early this morning to pick up the blower and the replacement bags of insulation. We got everything all set up by about 10:30 am and began to work at a steady pace.
One thing that I found was the cellulose insulation created lots and lots of dust. At some points it was difficult to see in the attic, so I would have to move on to another area until the dust settled. Dust also filtered its way down into the house, and covered everything. My wife and daughter were out all afternoon, but upon return I was given a few dirty looks.
All in all it took us about four hours to fully insulate the attic. I left a small crawl way down the center of the house because I really don’t want to crawl through the insulation to get to things if at all possible. The rest of the attic is filled to between 12 to 14 inches deep. That should bring the attic insulation up to about R-49, which is the recommended R-value for this area (it is now the recommended attic insulation R-value for the whole country). Considering that most of the attic had 6 inches, with one area only having 3 inches, I think we should see substantial savings on our heating costs this year.
The cellulose insulation was pretty easy to work with. There is a chart on the side of the insulation bag, which gives you the R-value for several insulation depths for attic application:
| R-value | Insulation thickness | Thickness after settling | Max square ft per bag | Minimum bags per 1,000 square feet |
| 13 | 3.9 | 3.5 | 52.9 | 18.9 |
| 19 | 5.7 | 5.1 | 36.2 | 27.6 |
| 24 | 7.2 | 6.5 | 28.7 | 34.9 |
| 25 | 7.5 | 6.8 | 27.5 | 36.3 |
| 30 | 9.0 | 8.1 | 22.9 | 43.6 |
| 32 | 9.6 | 8.6 | 21.5 | 46.5 |
| 40 | 12.0 | 10.8 | 17.2 | 58.1 |
| 49 | 14.7 | 13.2 | 14.0 | 71.2 |
| 60 | 18.0 | 16.2 | 11.5 | 87.2 |
There is also a blown insulation calculator on line. I found it easy to understand and calculate how many bags I needed based on the square footage of our house and the insulation depth required. Even so, I still over calculated and we ended up returning several bags to Lowes at the end of the day along with the blower.
This evening, my back, legs, knees, head, arms are all sore from spending four hours crawling around in the cramped attic. All in all, it feels pretty good.
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Well you have probably had this LOOSE isulation long enough now to realize it was a BIG MISTAKE. The grey insulation DUST in your house will never end. OOOPS.
Actually DK, the LOOSE insulation has settled down several inches becoming a dense layer. There is no DUST in the house because I installed a proper vapor barrier between the attic.
It was not a MISTAKE at all, I have saved well over $3,000 in heating oil since I installed this. I’d call that a wise investment.
OOOOPS, don’t you look like an ass
DK, he probably properly sealed his home first. I have the same pitch problem. I acquired roll insulation and wonder if you guys think it would be bad to put it face down over vermiculate blown in? Over time the insulation has been blown away from the soffits and it is relatively shallow insulation. The rolled stuff will fit in between the rafters good. I have also bought the same soffit vents so that the moisture is controlled better. Do you think that the vapor barrier will cause any problems? Also, the previous owner put rolled fiber glass in with the vapor barrier up, should I replace it with vapor barrier down?
To answer Jesse.. The only vapor/moisture barrier on the insulation in the attic should be against the drywall. ALL other insulation has to have the paper removed from the insulation to prevent moisture build up.
As for the dust. It’s not an issue unless you have a really poorly sealed house. As long as your interior is trimmed out and all trim is caulked at the joints like it should be to stop air infiltration you will have little or no dust inside during application.
I prefer blow in over batts because batts are tougher to install and keep the gaps tight between them.
Cellulose is typically manufactured as a loose fill or stabilized product. Stabilized requires a mist of water through an in line nozzle that locks in the built in adhesive. This reduces the dust considerably and provides less settling, however this is usually installed by contractors. Most contractors are competitive and cellulose is very affordable in attics and especially if you are topping off over your existing insulation. They can usually do 1500 sq ft R-30 in about 30/45 minutes. The store bought cellulose is usually in 18.1# bags so your material cost is about .40 sq ft. An installer would charge about .60/.70 sq ft so your really not saving big bucks, plus the back aches that go with installing yourself.