Considering spray foam insulation in attick

[Oberlander]

I have spent a bit of time researching on this site and wanted to post my own thread to get some opinions from those who may be wise to the subject. My older pole barn is a wood framed and sided 26 x 32 x 12 with OSB roof decking and asphalt shingle roof. I did a complete tear off and put down synthetic underlayment followed by owens corning shingles a few years back. The roof is holding up great and has no leaks. At the time of tear off there was no areas of concern for moisture and the building was put up in 1998. Now I am wanting to insulate and climate control the building. I have gotten estimates to spray foam the underside of roof and gable walls in attick with closed cell and it seems very reasonable compared to hanging ceiling and doing blown in. Not to mention the quickness I could have it completed. I just have concerns about applying the product to the decking if a leak ever developed. The contractor states he does it all the time and has no concern. Would it make sense to put foam board directly under the decking, at least for the first 4-6 feet from soffet edge as this is where majority of moisture damage occurs? Pictures of interior of building attached.
Thanks to any that can offer advise.
Oberlander

 

[Nowater]

Closed cell foam stop the water from going further, but one still needs to fix the leak.

The foam will help hold your roof on in high winds and will offer superior air sealing. It will also make the building quieter, somewhat.

Mine is applied directly to the underside of the deck.

 

[Oberlander]

Thanks. Just want to be sure it couldn't cause accelerated moisture problems that may not exist now. Anyone with experience in the north? We can get a lot of standing snow on the 4-1 slope roofs here in ohio.

 

[yeldogt]

I use closed cell all the time -- get qualified person who knows how much to spray.

Closed does not allow moisture to flow .. properly applied roof ..does not leak. Any drips dry to the outside.

 

[tlspeed1]

I spayed the back side of my OSB. It works well, and haven't had any issues in 3 years of winters here in WI but that is pretty short period of time in retrospect.

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I would think one could lay in thin rigid foam between the trusses if you were concerned of needing to remove roof sheathing. It would be a pain and add to cost though. Or you take on the mind set that if you have a leak, you remove the faulty area, repair and just get it resprayed.

 

[bradpac]

You should be fine with spray foam, you just need to pay attention to the condition of your shingles as you won't be able to see a leak from the underside.

 

[Firstram]

Personally I prefer open cell foam, if the roof leaks the water will pass through the foam. With closed cell you'll never know there's a leak.

 

[yeldogt]

I have never understood this "leak" fear. Roofs leak at seams and junctions -- most framing will still leak through at those points.

Roofs don't leak throughout the field .... and with everything foamed -- there is no place for water to enter at the top.

Even with a flat roof -- you maintain them. What do you think happens with a small leak w/ batts?

 

[EdT]

I had spray foam insulation installed on a residential addition a couple of years ago. They used open cell foam for the walls and roof. I must say, it works very well the attic stays as cool/warm as the living space. In my case they recommended open cell for the above mentioned reasons of not causing very small leaks to become very large rotten places before you realize that there's a leak. I understand that a roof is not supposed to leak so that should not be a concern. Fact is, roofs do leak in the real world. I'm sure that there are regional and local preferences and contractors who recommend one or the other kind of foam depending on what's in their system at the moment so they don't have to purge it to change foam type. That was quite a production when they did the block foundation with closed cell foam.

 

[Firstram]

What do you think happens with a small leak w/ batts?

With batts/open cell, the water stain on the ceiling/floor would indicate the roof is in need of attention. With closed cell, a leak at the ridge would stay on top of the foam all the way to the wall. The framing could be waterlogged or rotten with no way to know.

 

[landlord30]

Once insulated, you will need a way to get all your heat back down towards the ground where you will be.

 

[Oberlander]

Thanks all. I have no fear of the integrity of the roof as I personally installed it and have faith in my work. My fear is the not being able to see a leak and small issue becoming much larger by the time its noticed. Open cell vs closed cell seems to be a big debate also. I think I will proceed with the closed cell as advised and just routinely inspect the roof. Knowing that if an issue arrises, the spray foam could be cut out in that area and reapplied after roof repair.

 

[yeldogt]

I had spray foam insulation installed on a residential addition a couple of years ago. They used open cell foam for the walls and roof. I must say, it works very well the attic stays as cool/warm as the living space. In my case they recommended open cell for the above mentioned reasons of not causing very small leaks to become very large rotten places before you realize that there's a leak. I understand that a roof is not supposed to leak so that should not be a concern. Fact is, roofs do leak in the real world. I'm sure that there are regional and local preferences and contractors who recommend one or the other kind of foam depending on what's in their system at the moment so they don't have to purge it to change foam type. That was quite a production when they did the block foundation with closed cell foam.

The open cell guys need to sell the product. It's not as good and has other issues in cold climates.

 

[yeldogt]

With batts/open cell, the water stain on the ceiling/floor would indicate the roof is in need of attention. With closed cell, a leak at the ridge would stay on top of the foam all the way to the wall. The framing could be waterlogged or rotten with no way to know.

People get roof leaks at penetrations --- valleys .. vents. Mostly because they are not done correctly.

The key to building properly is to understand that buildings leak. Proper buildings .. dry.

A properly installed cedar roof will drip over long periods of rain --- the cedar gets waterlogged. Why no rot on the deck ? Because, it can dry to the outside.

Don't use OSB

Don't trap moisture with impermeable roof underlayment.

maybe someone here has run into this foam caused roof deck damage from not seeing a leak -- I have not.

A foamed deck will stop water from getting in -- say when an ice dam would occur. After the event .... it dries ? With batts you have wet insulation and water damage?