Insulation

[Mtsoxfan]

I know of a house that was for sale for $800,000 in my area that used open cell spray foam on the roof that hasn't been able to sell because the foam is holding so much moisture that it's rotting out the roof. The house is only a couple years old, but the shingles look like they are at the end of their life. It's really bad.

I've seen a few metal buildings with open cell foam insulation that are visibly rusting on the outside. They need to have the foam removed, but haven't done so yet and they are trying to find an option to the moisture issues caused by the foam.

I've never seen an issue with closed cell foam on a house or metal building.

I personally prefer fiberglass insulation over foam because of the price, but I'll be using closed cell foam on the ceiling of my great room when I'm ready to insulate it. My reasoning for spending the extra money is that it's the only way I'll be able to get the R Value I want with a limited amount of space. The isn't going to be an attic, just the thickness of my trusses and purlins for a total of 7 inches.

If I was going to insulate a metal building, and I had a limited budget, I would fiberglass the walls, and try to put a ceiling on it so I could blow in fiberglass in an attic. Using metal R panels for a ceiling allows you to go 4 feet for your joists without any issues. If that wasn't possible, then closed cell foam as thick as you can afford would be the only other good option. I don't see any advantage in cost by buying sheets of foam and trying to fit them into place. You still need to buy cans of foam to fill the gaps and tape all the seams. The YouTube versions that I've seen of this being done convinced me that it's not a good option.

When finishing off my walkout basement, I used 2" foam board using can foam to seal edges and joints. R 19 fiberglass after that. No issues so far, but then again, once wall up, how would you know?
Went that route compared to spray foam, $8k vs <$1k
I thought only closed cell spray was to be used on exterior walls, because of open cells ability to hold water???

 

[EddieWalker]

From what I've been told by the people who paid for open cell foam on their buildings, they insulation company told them that open cell was just as good as closed cell, but a lot easier and cheaper to install for just a little lower R value. In the metal buildings, they will spray it thicker to make up the difference and still be a lot cheaper then closed cell. I never met anybody who had open cell foam tell me that they where told that it holds moisture, or that there where any issues with that moisture being in contact with the building over an extended period of time.

 

[dieselscout80]

I've seen many articles that comment on how the bubble insulation r-value isn't accurate. It's really only R-1.5 or so. It works well as the 'outer' layer for a pole barn though as it won't be damaged by water and doesn't support birds or mice nesting in it like fiberglass batts.

Personally, I'd go with the rigid foam board as your second layer. XPS, EPS, and polyiso have different r-values per inch and different characteristics -- if I remember correctly, XPS insulative value degrades over time and polyiso's insulative value declines as temperature drops, but EPS has the lowest R value per inch. I'd verify that, though, as my memory may have jumbled up those details.

Did you exclude batts in the walls for some reason?

With the posts being on five foot centers and only 2.5” thick getting batts of insulation in without compressing it would be impossible.

 

[ROUSTABOUT]

Just curious, why was faom taken out so often?

I used a foil backed bubble wrap, 1/4" thick to insulate my garage doors. All the companies boasted R8, doubling up only brings to R10.

I will use bubble wrap all day long every day.

Foam held moisture, caused mold and dry rot when around wood. Caused rust out on metal buildings. My brother was on that foam kick when we built his shop. 80 x 80 x 26' tall. I showed him the info, he stepped off that train. Sure, the people that install it highly recommend it. Only has to last a year. We used chicken wire and roll vinyl insulation. He asked me about chicken wire. I said I absolutely hate it, but I don't want you to build a building without it.

 

[LouNY]

I will use bubble wrap all day long every day.

Foam held moisture, caused mold and dry rot when around wood. Caused rust out on metal buildings. My brother was on that foam kick when we built his shop. 80 x 80 x 26' tall. I showed him the info, he stepped off that train. Sure, the people that install it highly recommend it. Only has to last a year. We used chicken wire and roll vinyl insulation. He asked me about chicken wire. I said I absolutely hate it, but I don't want you to build a building without it.

I have not seen the issues you have, but everyone I know of uses closed cell on exteriors walls and ceilings as anyone that has studied up any knows that open cell is permeable while closed cell is not.
Some in an attempt to save some money will do 2" of closed cell then finish off with open cell. The complete air leakage stop with properly applied closed cell is as important in many areas as the R value.

 

[ROUSTABOUT]

With the posts being on five foot centers and only 2.5” thick getting batts of insulation in without compressing it would be impossible.

He can build the walls out of 2x4 and bypass his posts. On true metal buildings I put two batts plus the vinyl insulation already on building. Have wall out until wall surface just slips behind flange on I beam. Some want hidden beams so I bring wall out to bypass beams. I use 9" batts when they'll fit.

 

[ROUSTABOUT]

I have not seen the issues you have, but everyone I know of uses closed cell on exteriors walls and ceilings as anyone that has studied up any knows that open cell is permeable while closed cell is not.
Some in an attempt to save some money will do 2" of closed cell then finish off with open cell. The complete air leakage stop with properly applied closed cell is as important in many areas as the R value.

Up there in your neck of the woods it may be fine. Down here, we barely have winter and tons of summer. Valentine's day we usually plant the garden. October frost is occasional, but rare. Usually too hot to deer hunt in mid November.

The last house I built, the owner used foam but he just ran beads and sealed each stud hole. Just a small bead top, bottom, sides to seal from exterior.

I wouldn't to the not touch that stuff myself. Too many foam horror stories. I'd be total ICF if I lived up there anyway. Have me a four wheel drive with a set of them grippy tires and some of them V bar chains for each tire, with doubled up cross chains. Might even get me a plow blade so I can work in winter. Locking differentials too.

 

[Doorman63]

I have not seen the issues you have, but everyone I know of uses closed cell on exteriors walls and ceilings as anyone that has studied up any knows that open cell is permeable while closed cell is not.
Some in an attempt to save some money will do 2" of closed cell then finish off with open cell. The complete air leakage stop with properly applied closed cell is as important in many areas as the R value.

We are doing 2” closed cell on our barn build

24x40 with 10’ side walls

$6700

Contractor said approx r-14 with the 2” thickness. Adding an addition inch does not add the same r-value as the first 2” does per inch.

We will supplement with batts/etc

 

[dieselscout80]

If I was going to insulate a metal building, and I had a limited budget, I would fiberglass the walls, and try to put a ceiling on it so I could blow in fiberglass in an attic. Using metal R panels for a ceiling allows you to go 4 feet for your joists without any issues. If that wasn't possible, then closed cell foam as thick as you can afford would be the only other good option. I don't see any advantage in cost by buying sheets of foam and trying to fit them into place. You still need to buy cans of foam to fill the gaps and tape all the seams. The YouTube versions that I've seen of this being done convinced me that it's not a good option.

Eddie,

Sorry for the question, but what are metal R panels?

Will metal span five feet for a ceiling?

Would contact adhesive (3M 77 type) hold batt insulation in place until I can get OSB installed to cover it?

How bad would it be to compress R13 2x4 wall insulation into a 2.5” wall cavity?

 

[drumminj]

Adding an addition inch does not add the same r-value as the first 2” does per inch.

Pretty certain this is not true. A material has a given r-value per inch. The impact of each additional unit of r-value diminishes as you add thickness, but that's different than the material's resistance to heat transfer changing based on thickness.