Whether you are building a new structure or gutting and renovating an existing home/building I think that getting the best insulation for your buck is going to come up at some point.

Consider these points. R-value has significant importance and is also what building department officials use to approve or deny your project. Getting the highest r-value in your wall cavities should be a priority.

Air-leakage is usually the culprit of 40% or more of the heat loss/gain in your home. Stopping the unwanted air exchange between indoors and outdoors should also be a major priority.

Builders and renovators are still using basic fiberglass insulation in wall cavities giving homes an r-value of 13 with no air-seal. You actually cannot seal the walls because fiberglass needs to breathe to be effective.

Many are using cellulose or other mineral fiber types which give the home a similar r-value as fiberglass. Some dense packed insulators on the market have higher r-values and also do a pretty good job at air-sealing (wet cellulose spray.)

Open-cell spray foam is a great air-sealant and r-values in a 2×4 wall cavity range from R-13 to R-19 depending upon the density of the foam.

Now we will get to the meat and potatoes of this post.

Having 1″ of Closed-Cell spray foam installed gives you an r-value of 6 or more, is the best air-sealant, adds structural strength and is an approved vapor barrier.

After the closed-cell foam is applied your options are endless. You could go with an open-cell foam, cellulose, mineral fiber insulation, etc.

Of course filling the wall cavities up completely with closed-cell will give you the best insulator but can run you somewhere in the ballpark of $2.80-$4.00 per sq’.

By combining one inch of closed-cell spray foam and an alternative you would be looking at a ballpark of $1.40-$2.50 per sq’.

That is where the value comes into play. Think about it before you decide one way or another folks.