My 30x40x13 pole building build started today here in NW NJ. I will be doing the walls and roof with closed cell. A few insulation companies stated 3 inches in roof and 2 inches in the wall is all you need . The building will have radiant floor heat, 6 insulated windows, 1 12x12 garage door insulated r9 and 1 man door. I plan on keeping it 60 degrees. The ceiling will be metal and I'm on the fence trying to decide if blowing in cellulose ? Whats your opinion on the spray foam thickness? One contractor is saying go open cell?
Spray foam closed cell thickness
- Thread starter skippydoo
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finn
Well-known member
We used open cell in an addition to our house, as recommended by the insulation contractor. He did a flash coat of closed on the basement walls and finished up with open cell.
What I got out of the discussion is that closed cell is more expensive, so some clients equate that to being better. The R value per inch is higher with closed, but a standard studded wall, especially a 2”x6” studded wall has room for open cell, applied thicker, at a lower cost, to attain the target R value.
This being The Garage Journal though, is prone to mine is bigger, therefore better, overkill thinking.
What I got out of the discussion is that closed cell is more expensive, so some clients equate that to being better. The R value per inch is higher with closed, but a standard studded wall, especially a 2”x6” studded wall has room for open cell, applied thicker, at a lower cost, to attain the target R value.
This being The Garage Journal though, is prone to mine is bigger, therefore better, overkill thinking.
dynahoe
Well-known member
open cell can hold moisture. there's a you tube video showing liquid leaching thru it,.like fiberglass it can get moldy
jack stand
Well-known member
dave_dj1
Well-known member
Closed cell is R6 per inch if I recall correctly.
R12 I would think in the walls is minimal. I explain it to my customers, it's the product that pays you back every single day whether you are heating or air conditioning.
Check with local/state codes.
R12 I would think in the walls is minimal. I explain it to my customers, it's the product that pays you back every single day whether you are heating or air conditioning.
Check with local/state codes.
StingRay
Well-known member
I wouldn't go open. I have 3" in my walls. At the time I was told R7 per inch. 1" will seal it up and then conventional can be used over it. You won't get the insulation value of all foam though. Foam will stiffen the structure and make it a lot quieter inside and also outside if you happen to remaking a lot of noise in there.
dave_dj1
Well-known member
Two-pound foam, also known as closed-cell foam, has a density of about 2 lb. per cubic foot and an R-value of 6 to 6.5 per inch. Two-pound foam is significantly more expensive than half-pound foam. Closed-cell foam is a vapor retarder.
Info from the web.
Info from the web.
bahamasair
Well-known member
When I used to do spray foam we would typically do open cell on the underside of the roof so if there is ever a leak you will see it and know roughly where it is. Closed cell would trap the water between the foam and plywood and you wouldn’t know you had a problem until the wood rots out and fails. Walls would depend on the thickness because of the cost difference between open and closed cell.
I did 2.5 minimum on the walls in NJ on a flash batt addition about 12 years ago in NJ -- we did 3" on the roof deck. 2.5 was recommended at that time as the minimum for condensation elimination. This was closed.
Closed foam does not allow moisture to flow through -- the only concern is to have enough foam so the interior surface of the foam is not going to be below the dew point in the winter. You don't want to have any moisture condense inside the wall.
With open cell foam you need a minimum of 5 inches to create a full air barrier and you still have the moisture problem ... I would not use in in NJ (open cell)
When we did the flash and batt -- after the foam was done it was really enough .. but we had to add the batts to the 2x6 walls and roof to get the r value needed for code. Insulation value declines as you get thicker .... have heard of doing a very thin layer of closed to seal everything up and then go with all open. Again, it's the condensation ... not worth the small savings in my opinion. The battle between the open and closed camps continues
Closed foam does not allow moisture to flow through -- the only concern is to have enough foam so the interior surface of the foam is not going to be below the dew point in the winter. You don't want to have any moisture condense inside the wall.
With open cell foam you need a minimum of 5 inches to create a full air barrier and you still have the moisture problem ... I would not use in in NJ (open cell)
When we did the flash and batt -- after the foam was done it was really enough .. but we had to add the batts to the 2x6 walls and roof to get the r value needed for code. Insulation value declines as you get thicker .... have heard of doing a very thin layer of closed to seal everything up and then go with all open. Again, it's the condensation ... not worth the small savings in my opinion. The battle between the open and closed camps continues
Mark in Baltimore
Well-known member
Here's the quote I received three years ago for closed cell in our garage:
3. Spray apply to the underside of garage roof deck sheathing.
Approximately 507' SF = 1,014' BF @ 2" inch thickness = R-14
4. Spray apply at all garage exterior facing wall cavities including gable ends.
Approximately 731' SF = 1,462' BF @ 2" inch thickness = R-14
3. Spray apply to the underside of garage roof deck sheathing.
Approximately 507' SF = 1,014' BF @ 2" inch thickness = R-14
4. Spray apply at all garage exterior facing wall cavities including gable ends.
Approximately 731' SF = 1,462' BF @ 2" inch thickness = R-14
Itsjustdirt
Well-known member
What is the ROUGH cost of either of the weights? I’ve only dealt with fiberglass but this stuff is interesting.
Mark in Baltimore
Well-known member
$2,600 for our 22' L x 19' W x 9' H garage.
pamike
Well-known member
4 in open cell in wall cavity and 4 in of closed cell on back side of ceiling tin. Shop is TIGHT...
While it's based on SF -- there are minimums and some projects can be complex. A big open building is cheaper vs doing a house. With foam ....everything not being covered must be protected.
There is also a wide difference in regions --
theoldwizard1
Well-known member
Closed cell has about TWICE the R value as open cell.
For ceiling/roof AT LEAST twice as much as the walls. 3 times would be better,
Lelandwelds
Well-known member
Which foam is a better choice and how thick depends on which region the building is located. Read articles from "Building Science Corporation" about moisture control and building movement. The "Pretty Good House" and "Passive House" movements have some good info. There's a university in a cold region that has some cool thermal images of convection inside a wall.
Closed cell can dent your sheetmetal but strengthens walls. I like open cell. Cellulose is good and better than fiberglass in a fire. It slows the spread of fire but is more work for the fireman to verify fire is out.
Closed cell can dent your sheetmetal but strengthens walls. I like open cell. Cellulose is good and better than fiberglass in a fire. It slows the spread of fire but is more work for the fireman to verify fire is out.
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homebuilt burner
Well-known member
I did 1 1/2" closed cell and 3 1/2" of fiberglass in the walls of my shop. Then 16" of blown cellulose in the ceiling and am very happy with it.
Lelandwelds
Well-known member
That would be a respectable amount of insulation here, especially in a shop. I like all the different insulation choices available today. I have been in many buildings that are far more comfortable than I remember from the 1970s.
I wish somebody would adapt the metal insulated panel stuff used in reefer warehouses to housing and small construction. The one with built-in standing seam roof is especially fascinating. Around here, even building with SIPS isn't common.
I doubt energy costs will go down.
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Randy in Maine
Well-known member
Once I figured out the cost of closed cell foam in my 40x28x12 shop, it was very cost effective to just use SIPs.
Savings also included less lumber, less labor, less time and less waste material. Plus it insulates better and has less infiltration.
Savings also included less lumber, less labor, less time and less waste material. Plus it insulates better and has less infiltration.
In cold climates the thickness is based on condensation -- a very thin layer will seal ... but it's the condensation that you have to worry about. That's different in various climates .. so the thickness will be different.
Closed cell foams ability to eliminate air movement is the reason for it's great insulating value ... nothing else does this.
Many times people use foam in walls (only) because it's so difficult to seal all the various leak points with anything else -- plus you are gaining more R vs what is possible with any other product. Cellulose is often recommended for the ceiling after drywall is installed -- while this is better vs using fiberglass .... it's not going to get you to the level of using foam.
The benefits of foam are easier to see and feel as buildings get larger -- unless you can experience two similar structures .....one with foam ... it's hard to show how good foam really is.
Part of my studio is SLP's -- they do work ..and are great IMO for utility buildings. Finding knowledgeable builders is the problem in many areas.
Closed cell foams ability to eliminate air movement is the reason for it's great insulating value ... nothing else does this.
Many times people use foam in walls (only) because it's so difficult to seal all the various leak points with anything else -- plus you are gaining more R vs what is possible with any other product. Cellulose is often recommended for the ceiling after drywall is installed -- while this is better vs using fiberglass .... it's not going to get you to the level of using foam.
The benefits of foam are easier to see and feel as buildings get larger -- unless you can experience two similar structures .....one with foam ... it's hard to show how good foam really is.
Part of my studio is SLP's -- they do work ..and are great IMO for utility buildings. Finding knowledgeable builders is the problem in many areas.
Jon_E
Well-known member
I glued strips of 2" polyiso board in my wall stud cavities and sealed the perimeter with can foam, and then applied 1-1/2" of closed cell DIY foam over the top of it all. So it's a total of 3" to 3-1/2" everywhere, probably a minimum of R15 and up to R20 in spots. In my ceiling I used 2 layers of polyiso and sealed it with spray foam. So that's probably more like an R30. The polyiso cost me nothing but my time and effort, which is why I did it, otherwise I would have sprayed 3" of closed-cell in all the walls and 6" on the ceiling.