2-Part Foam R-Value: 2lb vs 16lb

[BenBowSirocco]

Does anybody have data on which density has the highest R-value of the closed cell urethane foams?



My supplier sells 2lb up through 16lb. My first thought is that the 16lb density should be better- but that is nothing more than a guess.



Figured somebody has done testing on this.

No hits from google- I just get stuff about insulating houses.

[Benz]

In house insulations at least, higher density has higher R-value, and a higher price tag.
I don't know if they use the same type of foam as you would on a boat.

[GordMay]

The higher the density of the spray foam, the higher the R-value per inch.
The R-value of high density closed-cell foam is about R-6.5-7 per inch.
The R-value of low density open-cell foam is about R-3.5 to R-3.6 per inch.
Open-cell spray foam is also vapor-permeable [absorbs and holds water], whereas closed-cell foam is not.

The Difference Between Spray Foam Densities
➥ https://www.paragon-protection.com/t...oam-densities/

[BenBowSirocco]

Thank you Gord.

Any chance you saw numbers for the 2lb vs 16lb?


It says higher density the better- okay, but how much better? They are both closed-cell.

[boatman1]

I’ve been under the impression that one would opt for the denser foam if a structural component was required. The really dense foams permit a properly designed and executed shape to be incredibly strong. For reefer insulation I believe that the lightest/cheapest mix will be just fine.

[Jack C]

Depends on use. Filling a rudder, go for the heavy closed cell. Refrig insulation, non structural, go for closed cell, weight according to the R value you need.
Space in a refrig can expensive and limited so if you have limited space use a higher R value. Eventually water will get into open cell refrig insulation.

When I insulated the attic of my house I used open cell under the roof and closed cell in the knee walls.

The open cell was cheaper and roof leaks are visible from the underneath so they can be found and fixed. Imagine finding leaks in the roof with closed cell.

[MikeHoncho]

I think you are looking at just volume of foam. Read the article attaches to the second post, it explains a given surface area = a given weight of foam. It appears a 2 pound volume will cover a smaller area than a 16lb area given the same application thickness