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Open or closed-cell foam?

Mescher's picture

Brand new here. 1st post.  So I'm getting close to completeing a long project of building a 30'x42' detached garage that I intend to heat. 45 degrees most of the time and a little warmer when I'm working.  I plan to be here another 40yrs or better so I want it as efficient as possible with no problems down the road.  I'm in the north part of zone 4.  Should I use open or closed cell foam in the walls?  Benefits and potential problems with either?

Thanks

The bitterness of low quality will remain long after the sweetness of low cost is forgotten.

While open cell is cheaper... (post #207093, reply #1 of 9)

While open cell is cheaper... it breathes.  That means moisture can penetrate the insulation.

Closed cell has a higher R value AND doesn't let in air or vapor.  Generally, Closed cell has more capabilites that you are likely to be looking for.

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Yeah, according to some (post #207093, reply #2 of 9)

Yeah, according to some charts open-cell foam is only half the R value of closed-cell, putting it in the same general range as fiberglass and cellulose.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Still puzzled on that one.  (post #207093, reply #3 of 9)

Still puzzled on that one.  Closed cell would be sprayed 2", 2.5" or 3" thick (R-14.8, R-18.5, R-22.2).  Open cell will be sprayed 4" thick or fill the 5.5" cavity (R-15.24, R-20.95)  So I'm not sure the small difference on R-value and minimal cost difference for compareable R-values is much to be concerned about.  Here's my real concerns;  With open-cell being somewhat flexible and closed-cell more rigid, some say closed-cell and can shrink away from the studs over time creating air gaps.  I'm told closed-cell loses some insulation value as it ages and the blowing agent defuses.  Some say with closed cell you wouldn't know if you had a leak until its caused much bigger problems.  And are there any other differences I should consider?  What's going to be the big differences over the next 40years? 

Thanks

What's going to be the (post #207093, reply #4 of 9)

What's going to be the big differences over the next 40years?

No one knows.  If you want certainty, don't build a house.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

I'm planning on living here (post #207093, reply #5 of 9)

I'm planning on living here for the next 40 years or better so if closed cell could shrink back and crack away from the studs leaving air gaps I'll definitely rule that option out.  That would defeat half the purpose of using spray foam (to seal the building tight).  Or is that someones unfounded opinion?  I'm sure their are other pros and cons of open & closed cell I'm not yet aware of.  That's why I'm asking if anyone else here has any points to consider before I make the choice for open or closed cell.  It's a long term commitment.  I don't mind spending extra time or money to do something right the first time to save headaches and time redoing something later on.  The best option will is also the one that will make the building the most efficient saving me money every year for the next 40 years.

Thanks

The bitterness of low quality will remain long after the sweetness of low cost is forgotten

 

My understanding has been (post #207093, reply #6 of 9)

My understanding has been that the propensity to shrink depends to a large degree on the mix and hence the skill and training of the installer.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Those "Some" people are the (post #207093, reply #7 of 9)

Those "Some" people are the open cell foam guys trying to sell their inferior product.

Like everything, closed cell foam needs to be installed properly.  That means the mix must be right, install temp must be within bounds, and it can't be sprayed too thick on each pass.  It's not art, it's just dilagence.

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Thanks guys.  That helps.  (post #207093, reply #8 of 9)

Thanks guys.  That helps.  Was hoping to hear some positive about closed-cell.  Open cell cant be that tight if you still need a vapor barrier.  Also had a good conversation with an installer about the same causes for problems of improper application.

Insulation (post #207093, reply #9 of 9)

As you can see on the net, spray foam of all varieties has its problems, it takes a skilled operator, the surface being sprayed needs to be at the correct temperature and the humidity of the day needs to be perfect. How often will you be lucky enough to get these things together?

Compare this with Dow Styrofoam/polystyrene sheet, Dow brought this to market 51 years ago, I first used it 46 years ago.

The stuff is still in the same condition today as the day it was installed. No problems.

Your proposal having a shed that is used from time to time and not lived in, will fit any form of sheet polystyrene.

From a cost point install it on the inside of the frame. If you feel that later on you may live in there and may raise the internal temperature, then fit the polystyrene on the outside of the frame.

Polystyrene is a closed cell foam board, it is made of very thin plastic cells each with a small bubble of air, cost wise its as good as you can get. If you want performance and high expense use Aerogel.