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Comparison of insulation price per sq. ft. per R-1

One would think there should be a chart that compares the range of cost between different types of insulation (per sq. ft. per R-1). However, I haven't come across any reference.

Does anyone know a range of the prices off the top off their head for various types of wall insulation (polyiso, EPS, XPS, cellulose)? I know prices can vary wildly within a city and what volume your are purchasing, but I'm guessing that there are some rules of thumb that builders tend to go with.


Asked by subahn
Posted Nov 15, 2012 6:05 PM ET
Edited Nov 16, 2012 9:51 AM ET


9 Answers

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EPS runs ~8cents/ F-ft f.o.b. the distributor's lot, most figure with scrappage for cutouts on windows it's more like 10cents/R-ft installed. Iso is usually in the same range as EPS, XPS is typically ~20-30% more.

With cellulose it depends on the density and installation method. Open blown in attics at 1.2lbs density is under 5 cents/R-ft installed, but dense-packed at 3.5lbs density in netting it can sometimes hit north of 15cents/R-ft., but 12 cents for sure. It really depends on how big a PITA the job is for setting up netting (or drilling & blowing behind gypsum or sheathing.) Mid-density 2-hole method cellulose cavity fill is usually under 10cents/R-ft, but again, varies quite a bit with pain-factor.

Open cell polyurethane sprayed in open stud bays has a comparable to dense-packed cellulose.

Closed cell spray polyurethane is usually about 17cents/R-foot, give or take a coupla cents.

Answered by user-1004076
Posted Nov 15, 2012 6:23 PM ET


Thanks for the detailed reply.

I didn't expect that EPS would be about the same price as polyiso.

Answered by subahn
Posted Nov 15, 2012 6:30 PM ET


There are several reasons why it is difficult to put together the chart you would like to see.

First of all, prices for insulation vary widely across the country. In some areas, for instance, cellulose is common and cheap, while in other areas it is very rarely installed and therefore expensive.

For some types of insulation (for example, rigid foam), it makes the most sense to compare the price of the materials without the cost of the labor to install them (because they are installed many different ways, so there is no "average" labor cost). However, spray foam insulation always includes the labor to install it, complicating comparisons.

In any case, I did my best to come up with cost information for purposes of comparing different insulation products, and I included that cost information in my article, A Buyer's Guide to Insulation. Check it out; perhaps you will find it helpful.

Answered by user-756436
Posted Nov 16, 2012 9:56 AM ET


Thanks Martin. It seems like the "Buyer's Guide to Insulation" supports the idea that all foam board costs about the same $/R/sqft. With that in mind, why isn't polyiso more popular if it has a thinner profile and is more environmentally friendly than other foam boards? When I go to my local Home Depot I can find many stacks of EPS/XPS but no polyiso. I understand that polyiso absorbs water, but if your walls are taking on enough water to saturate the foam, you'll probably have much bigger issues than wet foam.

Answered by subahn
Posted Nov 16, 2012 10:25 AM ET


I don't know what's going on at your local Home Depot, but foil-faced polyiso has been stocked by lumber yards in my area for at least 20 years.

Answered by user-756436
Posted Nov 16, 2012 10:55 AM ET


I think finding a source for polyiso might be specifically a Midwest problem. I'm from Madison, WI and I needed about 50 sheets for a basement insulation project. I went to about 6 different big box stores and lumber yards without success. Most people gave me funny looks when I asked about polyiso. I finally found it at an obscure building supply company (shout out to Badgerland Supply!). Maybe other builders on this forum can confirm that it is rare to see polyiso used in the Midwest (vs. EPS or XPS)? I could be totally wrong.

Answered by subahn
Posted Nov 16, 2012 11:18 AM ET


There are midwestern polyiso manufacturing plants, I'd be surprise if it were hard to find. Building supply houses that cater to the commercial building rather than home building or home-center box stores, would be a good bet. I've yet to walk into a Lowes or Home Depot anywhere in the US that didn't have at least a couple of thicknesses of iso, but I haven't been in Madison for more than 15 years.

Reclaimed roofing iso/EPS is another thing. In southern New England there are multiple vendors handling it, but few bother to advertise (other than freebie craigslist ads.) The only one I know of that even has a website is InsulationDepot.com- they will ship nationally from a handful of distribution locations, but only in volume, not a couple sheets here or there. But they'll also do cash & carry on small lots if you have your own truck and live near one of their distribution warehouses.

Answered by user-1004076
Posted Nov 16, 2012 11:57 AM ET


"I've yet to walk into a Lowes or Home Depot anywhere in the US that didn't have at least a couple of thicknesses of iso..." •• You won't find it in Fairbanks. And fer git asking a store in the Lower 48 to ship up here; they don't do that. I tried w/ Roxul. Very strange, but Sears is the same way.

Answered by jklingel
Posted Nov 17, 2012 2:30 AM ET



I'm in West Michigan and can report that I buy it very regularly at the big boxes--Home Depot and Menards (I believe Menards is Wisconsin based). Menards stocks fairly good sized quantities, as I often buy 40-60 sheets at a time. Lowe's curiously does not carry polyiso. I have found asking for poly iso is a barrier to entry--ask for foil face foam.

Answered by user-755799
Posted Nov 17, 2012 4:55 PM ET

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