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Insulation project

Posted by admin on Dec 24th, 2008
Dec 24

We live in a home built in 1952, which apparently is before the concept of insulation. Last spring we tackled insulating our attic. It was probably, at best, insulated to an r-value of 5 in a couple of areas and completely devoid of insulation in most places. Now it’s probably somewhere between an r-value of 30-35 with 8-10 inches of blown in cellulose insulation. It cost us about $350 for the materials ($325) and blower rental ($20) and about 3 hours of our time one afternoon. It was a step in the right direction, but it didn’t have much of an effect in the heat this summer since the walls aren’t insulated.
One of the big projects I have slated for this winter is to finally insulate our walls. I’ve been looking into all of the different insulation methods and narrowed it down to two in particular – denim cellulose and spray foam. Both of which are (or at least can be) green, and I can do them myself. Without going into too much detail, the decision was ultimately made based on ease of installation and overall r-value. Cost was also somewhat of a factor initially, but comfort won out over cost in the end and I decided on soy foam insulation. Here are the basic comparisons base on 1200 sq ft of wall space (@ 1 inch deep):




    • installation requires at least 2 people and a hopper that can be turned off/on by the person applying the insulation


    • total cost for 1000 sq linear ft = $1050 (sorry, can’t find the link at the moment)


Spray foam (soy) Thanks for the correction Jamie!



    • single person insulation is feasible


    • total cost for 1000 sq linear ft = $1370


So for about $300 more than cellulose insulation we’ll be getting twice the rvalue per square inch. The decision was pretty easy in the end. There is one other “honorable mention” that I should point out. It is still green in the long run and a little closer in price to the cellulose insulation at about $1050 as well, although you will need to keep in mind that the foam I listed above includes shipping and 17 installation tools, while this kit does not (at least not at the time of this writing). I’m hoping to complete this project by mid-January.

5 Responses

  1. Jamie Says:

    Chris, i’m quite interested in your insulation project. Our house (1905) in Seattle drafts like a GP-medium. Are you at all concerned about the ability to control the thickness and, thus, R-value when spraying into the walls? The calculations all seem to be based on 1″ but does the foam somehow settle into 3.5″ cavities at around 1″ and expand beyond that? While I am attracted to the other benefits foam seems to offer over cellulose, I am suspicious of how the foam settles into the walls leaving cavities, overfilling, underfilling.

    AlsoI looked at the link to Foam-it Green and they state that their product is NOT soy-based but rather polyurethane. Were you finding soy insulation products somewhere?

  2. admin Says:


    You are absolutely correct, the spray foam I listed actually isn’t a soy based foam. Thank you for setting me straight on that and I apologize for not getting that right. I’m not certain how I came to that conclusion initially but I’m guessing I was due to looking at a large number of insulation websites.

    In reviewing their website a little closer this time they do still provide a greener solution than traditional spray foam insulation in that they subscribe to TerraPass to offset each individual kit. They also claim to be “100% Free of CFC’s, VOC’s, Penta-BDE’s, Urea Formaldehyde”, which is excellent. For more information on why they are considered “green” please read this.

    As far as the 1″ calculations, that is just a standard base measurement (a 12″ x 12″ x 1″ section is generally considered to be one square foot). Here is probably a better explaination. For your situation you would multiply that by 3.5 to get your actual r-value and total amount you’d need. The site claims that the foam won’t sag or settle.

    Hopefully this answers all of your questions, but please feel free to comment again or to contact me directly at webmaster@ (THIS DOMAIN) .net.

  3. Back to my eco-projects again | Says:

    […] attention. Things that I have on my list: solar oven, micro turbines, a second effort towards my insulation project, and building my own solar panels. For now, here are a couple of links to some cool products that […]

  4. Home Insulation Says:

    Insulation is an excellent way to make your house energy efficient. Before doing the insulation, it’s highly recommended to do some inspection on the house to rule out all air leaks. There is no point in insulation if you haven’t weatherized your home.

  5. admin Says:

    Excellent point, and I definitely agree. Thanks for posting your comment!

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