Insulation of roof

[dstrbd488]

I have a 12x32 barn style shed that I’m fixing as best I can into a shop. I be got the fiberglass insulation for the walls and 5/8 Sheetrock for the walls but I’m at a loss for what to do about the roof area. It is a metal roof that is attached directly to the rafters and I’m worried about condensation forming between the metal and the insulation. I’ve been thinking about using form board attached directly to the metal with some type of adhesive. I looked into the spray foam but it’s a little more pricey than I’m comfortable with for a shop/man cave

 

[gmakra]

Is your roof pitched or flat?
If its pitched you could install vent on top of your ridge.
You can use construction tie wire to hang your foam board from the rafters.
Another possibility is put a lite coat of foam then wire up the foam board.
Or just spray the whole thing

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[JimD]

If you spray foam it, you should not have a condensation problem because there will not be a path for moisture laden air to get to the metal roof. I agree with George's comment about a roof vent but you also need soffit vents and a path for air to flow between the soffit and ridge vent. That would be a better setup but will be difficult to achieve. Foaming it would be far simpler for you. I had the ceiling of my crawl space, the underside of the first floor, foamed with closed cell foam within the last year. It made a big difference. They only put in a couple inches but it also sealed everything up. In my case, I wanted to seal against higher humidity in the crawl space and I am on a lake with a remote chance that I could get water in the crawl space. So closed cell foam made sense. For your application in a ceiling, I think open cell would be fine and it is significantly cheaper. I did not price it both ways but I wonder if foam boards would be cheaper than spray foam. They are certainly not cheap.

 

[dstrbd488]

Is your roof pitched or flat?
If its pitched you could install vent on top of your ridge.
You can use construction tie wire to hang your foam board from the rafters.
Another possibility is put a lite coat of foam then wire up the foam board.
Or just spray the whole thing

Handi-Foam 600 BF P10749, Spray Foam Insulation Kit, Closed Cell | eBay

Find many great new & used options and get the best deals for Handi-Foam 600 BF P10749, Spray Foam Insulation Kit, Closed Cell at the best online prices at eBay! Free shipping for many products!

www.ebay.com

It is “barn shaped”. We always called them mini barns when I was growing up

 

[zdorsch]

Are there any vents for the roof currently?

Another option may be to use the rigid foam and tape the seams.

Then place fiberglass below that for additional insulation if needed (although this would require more work to hold up the fiberglass insulation).

 

[jrfuda]

I agree with using spray foam. We live in a circa 1900 home that, as we've slowly remodeled over the past 9 years, we've had a pro install spray foam. It does cost a little more, but we would never have achieved the level of comfort we have in the old house using any other method. If you consider using spray foam for your shop, have a pro come out and give you an estimate. There's a breaking point where they can actually do it close to or cheaper than DIY. Small jobs are cheaper DIY and may not be touched by the pros, but they're great for the bigger jobs.

An important thing with spray foam too is the difference between closed and open cell sprays and how to ensure you avoid condensation. Open cell spray foam can still absorb moisture, has a lower R-value, has moderate sealing properties, but is better at sound absorption. Closed cell will not absorb moisture, has a very high R-value per inch, completely seals and adds structural integrity, but is not so good at sound blocking. Closed cell cost more per "R" also. The solution I used was 2 inches of closed cell with the remainder filled by open cell. This brought the closed cell inside of the point of the wall where the dew point could occur, met my R-value requirements, and saved me a few bucks. In my boys' room, The only rooms that has had the ceiling/roof completely foamed, the sound-proofing is so good that you cannot tell it is raining in even the largest downpour. It is also the most comfortable room in the house.

Bottom line is I don't think spray foam would be overkill for a shop and would probably be the simplest install.

 

[Jeff]

It is “barn shaped”. We always called them mini barns when I was growing up

Is your roof like this mini barn roof?

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[dstrbd488]

Is your roof like this mini barn roof?

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Yes it is.

 

[ralitaco]

What about those foam baffles? They create an air gap b/n the roof and the insulation.

 

[Gofor]

What about those foam baffles? They create an air gap b/n the roof and the insulation.

I used those on my shed and they work well. However, my shed has a layer of OSB under the metal roof and plastic barrier. (something to staple them to.) It may be problematic to attach them to the metal. I don't see tape lasting long in that environment. I suppose they could just sit on top of the insulation.

 

[FlyingRon]

What about those foam baffles? They create an air gap b/n the roof and the insulation.

Unnecessary and really not advised. They only exist because certain building inspectors weren't up to date with the technology. My neighbor has them. By the time I build my house, they'd wised up. Everything is sprayfoamed to the inside of the roof sheathing without issue.


Even without sprayfoam, you shouldn't have an issue if you install your vapor barriers properly.

 

[Oka]

Use Pre-engineered Metal Building insulation It comes in 24 36 & 48" width rolls some are 25 or 50 ft long, They have vinyl on the bottom. Typical way to install is to use tension wire and plastic or metal chicken style mesh.

Here is an example Steel building insulation 6"Th x 3'W x 50'L ST Reinforced w/ Batt ( 1 Roll) | eBay

Also if you are going to do it, plan on using a scissor lift if it is above 10 ft high. Forget what the cost is out there, but here is about 90/day or 300 /wk gotta have a flat floor though to use. If you are on gravel then it will be more casue you will need an rough terrain type.