Sunday, October 27, 2013

Cellulose vs Urethane Foams - Again

I've noticed that in much older posts I reported on costs of various types of insulations.  More on this here. We have now finalized our cellulose insulation contract with Greensaver - a not-for-profit in the Toronto area.  Costs for dense-packed cellulose insulation for walls seems to break down like this, at least on our project:

Walls:  4085 cubic feet, at 3.5lb/cf density = 14,300 lb cellulose, at 33 lb/bag, we need 433 bags at about $10ea. - so materials for the walls are $4330.

Attic:  4183cf at 2.0 lb/cf = about 8400 lb in the attic, or about $2550 worth of material.

Labour in the walls is about twice the material cost, and labour in the attic, about 70% of material costs.

Much thanks to Climatizer insulation of Toronto for providing a fantastic price on the material for our project!  (They've had a tour of our house and took a step to support us as a contribution toward green initiatives).  Here are the bags we will be using:

In the past I've noted that spray-foams are about 10x the costs of cellulose and the other fibrous insulations. There is a bit more to note regarding this issue, which has some impacts on the 10x difference.  I discovered this video on youtube: showing the use of pour foam - liquid foams that you pour into things.  This is very similar or the same stuff that is used in the spray foam process, (it is basically the same, but additives may differ).  The video points to Aeromarine Products, where you can purchase the foams right from the website.  You'll notice you can purchase about 500 cubic feet of 2# foam for about $3900 - which works out to $7.80/cf, or about 10.8 cents/sf-R.  This is still a lot more than cellulose, at $0.303/cf, or $0.0072/sf-R.  Something like 15x the cost on the materials.  Here is a place you can purchase spray-foam kits:, and they also give you the prices right online - I love it when they do this.  Here the price of spray foam on their largest kit works out to $14.3/cf - almost twice the price of the pour-foam.  This is some 30x the cost of cellulose, R for R (not accounting for the fact that cellulose takes about twice the space to achieve the same R levels - the value of space and the construction details required to build this space for cellulose are pretty variable - but then, we are also not accounting for the health and environmental footprints of the two materials, which are vastly different as well, with cellulose miles ahead on both accounts).  Note that labour costs are not included in the comparison, but given the labour portions noted above, we are still well ahead with cellulose.

Why is spray foam so much more expensive than the pour-foam?  Pressure vessels, and possibly additives - but mostly the pressure vessel/ hoses, gun, etc.  So the interesting point here is that if one must use urethane foam as a DIY, consider buying it in the liquid phase - that's what contractors do.  If you don't need to spray it on walls, but can pour it into a cavity, this is really the way to go.  In our case, we could have poured it into our walls - just like we will be 'pouring' the cellulose.

PS - We are purchasing larger amounts of mineral wool for our project as well, and Winroc has also given us excellent pricing on the material - again, to do their part to support 'green' projects.  Our cost for this material worked out to about $0.034/sf-R - about 4.7 x the cost of cellulose, not accounting for installation labour, which would reduce the cost advantage of cellulose, probably bringing it nearly even with the Roxul.


  1. I suspect that if you contacted a few spray foam installers for a quote you would find that their INSTALLED price for high density foam is similar to the prices you are quoting for foam only (about $10 per cubic ft). Still more costly than cellulose, but not as large a differential as your data suggests! Accounting for the lost square footage (at $300-$500 per sq ft), and increased construction complexity associated with holding and air-sealing the cellulose will further reduce the cost differential, as you noted.

    At present the biggest concern about spray foam is the large green house gas potential of the blowing agents used to expand the foam. The companies claim they have solutions in the works. If so, spray foam would look more interesting.