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.
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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.
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.
What's going to be the big differences over the next 40years?
No one knows. If you want certainty, don't build a house.
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.
Those "Some" people are the
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.
Insulation
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.