DIY spray foam sources for pole barn? Anyony have issues with foam?

[STx]

You don't really save much money with open cell vs closed cell, sure it's 1/2 the cost but, it's also 1/2 the R value per inch, so... If you want to save money, spray 2" - 3" of closed cell foam and then put batt insulation over it.

Air tight is just a side benefit of foam on metal siding, the real advantage is that foam will eliminate inside condensation in a heated building. Before we foamed our Morgan building (which we're using as a cabin), it would literally rain from the inside condensation if we turned on any heat in the winter. Since it was a small building (14 x 24), I got 2 of the DIY foam paks and sprayed it myself with a 1" layer of closed cell and put batt over that. It strengthened the building, quieted the rain and eliminated internal condensation. I would not even *think* about trying to do a building any larger than that myself. My results were good but you need the pro tools to do a large job and the machines are big $$$$. Controlling the temperature of the mix is VERY important, I had to do it ghetto by storing the bottles in a heated room until I got them up to temperature but the pros have heaters on their rigs. I learned the hard (expensive) way that if you spray it below an 80* material temp, you will not be at all happy with the results.

 

[bob112]

Here are my thoughts for consideration. R value is R value. Fiberglass, per R value is much cheaper. Cellulose is even cheaper but no way to install that unless I have finished walls. The issues with these insulating materials is air migration. Most glass insulation has an air/vapor barrier on the "inside" facing. If sealed properly, it functions as intended. However, If there is constant air circulation at the outside or unconditioned side of the insulation, physics laws take over and get air moving through the insulation which kills the R value. You can blow air through through fiberglass.

The only reason for condensation is warmer/moist air hitting a cooler surface in which the dew point is met and the cool boundary layer of air at that surface will give up its water and condense. Simply by not allowing that moist warm air to make contact with the cool surface will ****** condensate.

I have seen the majority of buildings done in my area by just pinching the glass between the sheeting and framing. So now you have air leakage through the metal overlaps and probably all the open pockets on the bottom and top so air is free to move around all day back there! Then you compress the glass so that R-19 glass is probably an R-5 at that point.... Then people ignore a good air seal on the inside, warm air works through the glass, condenses on the sheeting, and soaks the insulation, further reducing R-value.

I cannot claim to know it all here, thus my points in asking, but dare I say, being in the engineering field, I at least understand the physics of the matter. in all applications, we are effectively creating trapped air spaces and the air is what acts as a thermal insulator, ignoring natural convection which does occur. Closed cell foam can ****** convection but at some point, the costs get insane.

All I really need/want to do is find a smart/cheap/easy way to seal up the metal sheeting so the back side has very little air migration. From the sounds of it, foam might not be the best choice for sealing sheeting overlaps and maybe something as simple as spray rubber would be best. However, as some pointed out, if adhesion is broke, you are hosed. Urethanes and silicones seem to be the best fit.

How knows. I could end up looking at house wraps again, but in any case, getting that air seal is more important.

As far as why I don't want to just spray foam the whole thing complete comes down to cost and aesthetics for me mostly. Foam just ain't purdy...Not to say glass really is but I have seen them look decent enough.

Obviously this space will be 24/7 climate controlled. I have to weight certain other factors like the cheapness of my radiant floor heating, Geothermal heating/cooling, etc.

 

[boggen]

hardboard insulation (never remember correct term for it) comes in 4'x8' sheets just like plywood, but is insulation. is primary insulation in sheds. and then use of the "closed cell spray foam" name bran "great stuff". to fill in around the hard board insulation. along with use of the foil tape.

the hard board insulation, was generally cut almost for perfect fit, but for most part was cut slightly smaller from 1/8" to 1/4". and i relyed on the spray foam to fill in around the edges.

i did use the hardboard insulation nails (longer nails with a larger plastic washer on them) to hold hard board insulation in were i wanted it. once the spray foam fully cures, the hardboard insulation will not budge. or purposely trying to remove it.

i generally went with cheap hardboard insulation first up against the metal, then i went with a double sided foil hardboard insulation as the final layer. that foil seems to really help deal with radiant heat both coming into building but also keeping it in. a big issue was getting everything "air tight" as well.

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to note it. there are various fire codes / rules / regs you may have to deal with. some insulation requires that you put sheet rock or like on the interior walls.... some of the insulation out there toss a match and it just goes up instantly. and/or once it starts burning melting from a fire, the fumes are extremely toxic. hence some sort of fire barrier, from sheet rock or like (depends on code)

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for myself... i waited and waited and finally a real nice deal came up for hardboard insulation. menards big card incentive plus weekly add incentive, plus something else i want to say. added up to a nice reduce cost on the insulation.

i could of went with rolled in insulation maybe even blown in insulation. but to many mice, bugs, mold, etc.... just not worth it. it came down to a closed cell foam. and either it was going to be done by professional spray in job or DIY hardboard insulation. hardboard insulation won out.

 

[Cord]

Building a pole barn and have pretty much decided on a thin layer of open cell against the metal sheeting to work as an air barrier, then follow up with glass batts.

I have not totally decided on a foam thickness but I know that can only really be estimated as it varies a bit.

The main issue is I need to do about 14,000sf plus a few other things so probably closer to 20,000sf. These little DIY kits are a joke. I realize there are some "pro" work arounds here but if I can shoot auto paint and bed liners, I can shoot foam.... I am not yet sure of the specific equipment though. Wish I could just rent the equipment.


Anyone have anything to add here? I was also considering 1/4" foam board over the building framing before sheeting but taped joints are known to fail over time from thermal moment. My air seal is VERY important. I also considered a Tyvek housewrap product but seems a bit hassle to do.. BUT maybe that is BS considering the hassles of spray foam???

Basically I can do a house wrap to get air seal and install more glass...Or open cell foam against the inside walls, backed up with batts?

I do NOT like the idea that fixing or replacing sheeting with foam could be an issue. House wrap should be easy enough but I am still not sure on seams on that product as well as the nail holes in it.

The metal it's self is a air barrier, you just need to concern yourself with the joints. You can pretty easily tape these. I'd suggest using a Tyvek or similar tape that won't dry out like a duct tape does.

Oh, btw open cell foam is not a air barrier. Open cell resists air movement about as effectively as a sponge.

 

[taperbeaver]

I used to be a painter. You might want think also about down the road (i mean years). If you ever need to do any work on the roof with the underside foamed it might pop off do to walking. I also worked for an insulation company, they would used wrapped fiberglass in white plastic for reflective value to put on bottom of roofs. Good Luck

 

[EddieWalker]

In every trade magazine that I've read about reflective barriers in roofs, it's stated that there is no proof that it does anything. It is just a way to charge more for something. This is very common in windows too.

 

[TCJatko]

Isn't spray foam somewhat flammable? You might need to factor that into your plans.

 

[STx]

Isn't spray foam somewhat flammable? You might need to factor that into your plans.

Anything will burn if you get it hot enough, even concrete, but closed cell foam doesn't burn easily.

 

[TCJatko]

Anything will burn if you get it hot enough, even concrete, but closed cell foam doesn't burn easily.

I get that anything will burn, but isn't spray foam required to be covered with sheetrock, just like kraft-backed roll insulation?

 

[Luke'sScreenName]

I get that anything will burn, but isn't spray foam required to be covered with sheetrock, just like kraft-backed roll insulation?

... Or fireproof paint. But I think that is more about the gasses is releases not that it will accelerate a fire.