Monday, July 27, 2009

Adding Blow-In Insulation

I’d been thinking about adding some insulation to my attic for a while now. This year’s 30% tax credit gave me the final kick I needed to do it. I went to Lowe’s and bought 16 bags of Owens Corning blow in insulation which came with a free 24-hour blower rental. It was a tight fit but I made it in one trip:

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Maya read up on the installation procedure (pamphlet in hand) while I unloaded.


The first step was cleanup. It took a lot longer than I anticipated as there was more junk and garbage than I thought. Insulation works best when it’s fluffy and even so all this stuff had to go. Some “before” shots:

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After that came the main event. With my buddy Bryan feeding the blower, I crawled around the attic adding in 6-12 inches of insulation (the base was very uneven), bringing the attic up to R-49. Here are some “after” shots:

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Cost detail:


Some lessons learned or things I’ll do differently next time:

  1. Be more careful with estimates. I bought 16 bags and ultimately only used eight. I think I bought far too much for three reasons. First, I underestimated how much insulation I already had in my attic. Second, I think the charts the vendor supplies might be generous. Finally, I used data for a 1000sf attic but mine is more like 900sf. I easily returned the unused bags but hauling them around was a hassle.
  2. Put a sheet down around the attic access area. I had a lot of debris and attic dust beneath my attic steps. This would have been easier to clean up it I had put a sheet down. The shopvac did a nice job, though. Interestingly, the new insulation really was dust-free as advertised—90% of mess came from the junk I took out of the attic.
  3. Have something to entertain the helper. This job absolutely requires two people (one to feed to the blower, which is outdoors) but I’m told that job is pretty boring.
  4. Pick a cold day or do it earlier in the morning. It was a very mild day but damn it was still hot as hell up there. I was drenched in sweat the entire time. I cannot imagine what it’d have been like on a hot day. Jacket-weather or colder would be ideal since you have to wear long sleeves and pants anyway.
  5. Use more depth markers. I used about eight depth rulers throughout the attic (visible in some pictures above). I should have used 24 or more (they’re free). It would have made the process much easier as I wouldn’t have had to go back and forth so much stressing about an even layer. I’d certainly have done a better job, too.
  6. Collect some large pieces of cardboard in advance. I built little fences around our house fan and access steps with a bunch of chopped up boxes. This would have been much easier and cleaner if I had used larger boxes.

I still have one thing left to do: install the 2” board over the house fan and attic access. Currently these areas have no insulation at all. I plan to put two layers of 2” board over these, with a little insulation in between (hopefully about R-20). I might add a little framing, too, so they can be flipped up easily when the fan or steps are in use.

All told, I burned about 5 hours on the project, including two trips to Lowe’s. The project was more work than I expected but still easy enough (I hadn’t counted on the heat or amount of trash that I had to removed). Saving a mere $15/month (very roughly 10% of our energy bills) would give us an ROI of 12 months. I’m very confident we’ll meet or beat that.