Recommendations/experiences with spray foam for existing shop

[WinterDeere]

One other thing I'd research about a vapor barrier between steel roofing and closed cell foam is the possibility of trapping moisture between the vapor barrier and the steel roofing which could potentially destroy your roof... RUST.

A lot of installers like to spray the foam right onto the underside of the roof. My big concern with this was that the foam would follow the exact ridge countour of the existing roof, and make future replacement very difficult, so I fit rigid foam insulation into east joist bay and had them spray against that.

This has two advantages, in that it doesn't block off any existing soffit-to-ridge ventillation which may help keep the underside of the roof dry, but also makes future replacement much easier. It was very easy to fit 2' wide sheets of the stuff between my rafters (24" on-center... or as close as 250 years of settling allows them to remain), and I just pressed the rigid foam insulation onto the purlins, and used a few drywall screws to lightly hold it in place.

 

[RayIN]

I see advertisements for block foam in various sizes all the time. I plan to buy it in bulk and insulate the side-walls, the roof was insulated during construction.
When Westinghouse Electric had the 2 acre building they built here sprayed inside with a fireproof shredded-paper mixture, kinda like paste. It was still intact 60-some years later when the building was demolished.
It didn't look good, but it was effective insulation.

 

[CliffordK]

I'm not sure about soffit vents. If you have an open ceiling, they may not be needed in the traditional fashion.

I've picked out a pair of big industrial fans for the rafter peaks (walls) in the build.

 

[gsganzer]

Thanks everyone, for some good pointers.

When I redid my current shop and turned it into an in-law apartment, I used the reinforced vinyl faced fiberglass roll insulation before I set the new metal roof down. It was really simple to put down. The first roll is 4' wide, so it staggers from the 3' R-panel seams and subsequent rolls are 6' to continue that stagger. You put double sided tape down on the purlins and roll the insulation out, with the vinyl facing the climate controlled space. You can buy the insulation with a 3-6" tape tab on one side, so the vinyl overlaps and makes a perfect vapor barrier, insuring a perfect seal between rolls. You don't pull the insulation taught, you want it to "blouse" slightly, so it increases your R-value.

When you lay the metal on top, it obviously compresses the insulation over the purlins and it's easy to shoot the tek screws.

I wouldn't hesitate to use the roll insulation on any new building. You can buy various thicknesses and also different abrasion ratings on the vinyl vapor barrier, even the color, white or black.

 

[EddieWalker]

This video has some good information on foam. Go to the 17:30 point to hear the differences and reason for closed cell over open cell.

 

[gsganzer]

This video has some good information on foam. Go to the 17:30 point to hear the differences and reason for closed cell over open cell.

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Wow! The early part of that video shows a shop that was sprayed incorrectly, I guess by not spraying a "flash or tack coat" first. I can't believe how much the metal distorted. I'd be pissed if that happened to me!! That building looked like a total loss.

 

[workinonit]

Eddie, I just watched that video yesterday. It's a great vid for anyone wanting closed cell insulation and it lets you know just how little the average Joes like us know about closed cell insulation. That guy has been doing that for years and knows his stuff.

 

[mikester]

So, im coming up with a very fast, rough, 2800 sq ft of wall and roof area. It could be as low as $2.50-3/ sq ft per inch, but upto $9/board foot.

So, im thinking a min of $8,500; on upto $25,900. I have seen some people report as low as $1.50/bf; or $4320; but i doubt thats the price a homeowner will ever see.

If its much higher than $7500, I would seriously look at a kit. Kraken has a fire rated, 1900 sq ft kit, at $2999.View attachment 4274868

I did 2" closed cell. I wish I did more thickness. Buy once, cry once. The money I saved going only 2" disappeared into propane bills shortly after.

I tried one of those kits for a cold cellar ceiling and said never again! It's a messy nasty job. The pros use heated kit with high pressure metered pumps. Everything requires maintenance to keep running smoothly.

The home brew spray foam kits give you a few spare cheap nozzles and good luck keeping the nozzles unplugged and chemical ratios consistent. They are designed as single use throw away when you are halfway through the job.

 

[EddieWalker]

Wow! The early part of that video shows a shop that was sprayed incorrectly, I guess by not spraying a "flash or tack coat" first. I can't believe how much the metal distorted. I'd be pissed if that happened to me!! That building looked like a total loss.

That was something that surprised me too. I think there must have been something on the inside of the wall that forced the foam to do that when it cured. I can't think of how it happened any other way.

 

[EscapedSuburbia]

During Covid when everyone wanted to turn a van into a camper a lot of people tried using home center spray foam for insulation and ended up with bulged body panels when it expanded between a sheet metal panel and a piece of interior structure. I wonder if what happened to that barn in the video is from foam expanding between the exterior and a purlin.