Do the slightest amount of research and you will quickly find the cost of insulation varies greatly. Purchasing power and materials both play a role. Professional installers buy for less than retailers and big installers buy for much less than small ones. And home improvement websites all publish different figures.

A rough idea for insulation costs, from low to high:

  1. Cellulose
  2. Fiberglass
  3. Rockwool
  4. Cotton
  5. Wool
  6. Closed-cell foam

Note: These are averages, i.e. foam tends to cost more on the West Coast than the East Coast.

While costs vary greatly, we continually encourage common sense and context in decision making. This is a topic we have previously written about so a summary is simply: stop and think about what you are buying and manage your expectations against cost and product integrity.


First, what are the actual prices? Again there can be significant disparity but HomeAdvisor, and others, offer the below data. (The omission of r-value or other performance metrics only adds to the confusion!)

  • Cellulose is generally $1.00 to $1.33 per s/f
  • Fiberglass is generally $0.64 – $1.19 per s/f
  • Rockwool is generally $0.91 – $1.65 per s/f – according to homewyse
  • Cotton is generally 0.76 – $1.41 per s/f – according to homeguide
  • Wool is specifically $1.33 – $2.00 per s/f for batts and $1.57 – $2.55 for blow-in*
  • Open-cell spray foam is generally 35 to 55 cents per board foot**
  • Closed-cell spray foam is generally $1.00 – $2.00 per board foot**

* Wool ranges are for a 2×4 and 2×6, respectively, for both products

** A board foot is 1 square foot with material applied @ 1” thickness. The foam figures need to be multiplied by the number of inches installed eg 3” of closed cell foam is $3.00 – $6.00 per s/f in the example above.

See the full HomeAdvisor article HERE.

Now for the all important context. It is really important to keep insulation costs in perspective.

A 2017 NAHB report reveals insulation is 2.2% of construction costs (up from 1.8% 5 years ago). Construction costs are 55.6% of total costs which, in turn, makes insulation 1.2% of overall cost.

So what does this mean? For 1-2% additional cost against your overall spend you can select healthy, high-performance options for insulation. We suspect the space is confusing on purpose which is why we strive to provide transparency.

The key takeaway from a group simply trying to help you make informed decisions: Insulation is a minor part of home build or renovation budget which means for a few extra dollars per square foot it is possible to vastly improve the health and performance of your building envelope.

If your builder or architect can’t help, call us; we can, and do all day everyday.

Thanks for reading and keep well,


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2 comments on “Insulation Cost in Context

  • I am interested in batt insulation of r-value 21. Not sure of the dimensions, but I believe one wall is 3’x26′. A second attic space is approximately 4′ H x 5′ long. We need 5 1/2″ thick.

  • Thanks so much for the SUPER helpful, succinct blog post on hard cost and % of build! Sealed the deal for me- will not use anything but wool for our shuttle bus build! Health is wealth! 🙂

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