I find that apparently simple processes are more complicated than they look. So, please help me understand what it necessary and important in insulating a pole barn.

I have a wooden structure, with metal walls and roof. When it was built, rigid insulation was installed in the roof. That was pink rigid foam with a foil face towards the interior.

Now I want to insulate the walls and I have a couple of questions to sort out.

It seems that (R for R) white Styrofoam boards are half the price of rigid pink foam boards. In other words R6 Styrofoam is about twice as thick as R6 foil-faced pink foam but half the price. Is there a down-side to using the Styrofoam?

I expected to make the insulation airtight by metal-taping all the joints. But someone suggested I need a vapor barrier like visqueen (?) on the interior side of the foam insulation. Do I need the visqueen? It seems like the building materials are engineered to ventilate the backside of the foam through the vertical ribs in the metal siding and the open venting at the eaves and ridge.

I will be putting fiberglass panels (Like in commercial bathrooms or kitchens) over the insulation as my interior wall. I'm choosing that over anything else because 1)I can get them free, and 2)they seem fairly durable, waterproof and light-colored and somewhat reflective.

This seems simple enough until I get ready to dive in to it and then I wonder if there is something I still need to consider.

So: Styrofoam between the stringers, metal tape at joints and edges, fiberglass pre-drilled for ring-shank nails into the stringers, silicon caulk at the edges of the fiberglass panels. Can it be that simple or am I setting up a problem there?

So it is twice as thick per r value which means it isn't as good of an insulator. If you have completely fill your space with insulation, the rigid foam will provide more insulation power. I have not really used the stryofoam, but the one sheet I had was fragile, crumbled fairly easily, and looked to be easy pickings for mice and other vermin to make a home in. The rigid foam is pretty strong stuff.

IMO you are engineering an excellent job. Some might call it overkill for a pole barn, but as you outlined it should do a really good job. Have you compared the price of spray-on insulation to what you are planning? It is far better but a bit more costly. You have to decide if the difference in cost is worth it to you.

little white beads turn into a mouse playground....

I would look at one of two ways. Urethane foam is really good stuff and the shiny part you get on the inside acts as it's own vapor barrier. Either of the products I am recommending can be used for walls and ceiling. Don't mess with the other stuff.

The other is called metal building insulation. They can run it for you as wide as necessary so you have exact fits between poles and it comes with it's own vapor barrier, most people prefer white, as it makes the inside of the building brighter.

I'd certainly stay away from bead board, or the blue or pink foam. Not that the blue or pink is a bad product for the proper applications I just don't consider metal buildings that. Get two or three bids either way you go.

Are you keeping animals in this barn? I think Styrofoam can be hazardous if they eat it because it doesn't break down and can cause obstructions/choking.

No animals, except maybe a dog for company when I'm out there.

Cost is a primary consideration.

The Styrofoam I would use would about fill the space between the stringers. The pink board would only fill about half the depth.

One end of the building will be built out as a gun room with a built up floor of plywood over insulation over visqueen over the slab.

The majority of the space will be multi-function workshop: auto shop, machine shop, etc. sharing the floor space.

I wonder if mice are a factor or not. The building seems to be quite tight, it's been up several years and I've never seen signs of a critter in it. And the walls will be pretty tightly built. Maybe I should use the pink foam on the lowest tier and Styrofoam on the rest?

I'll see what else I can learn about the other materials mentioned.

Thanks!

I'd spray it.

Correct> Urethane foam. Best way to do it.

Does that eliminate putting the panels on the wall?

For a barn, i wouldn't put those panels up. You likely will want something a bit nicer in the gun room. The spray urethane is sort of a tan creamy color, firm surface, and it's own VB. If you want it brighter (very few barns and shops have adequate lighting, IMO) rent a sprayer and paint it white.

Spray would be the best insulation, best VB, most expensive, etc. get a bid and price out your labor on cutting endless foam panels up. Pole barn will have mice regardless of what it 'looks' like, no way to stop them. Factor in how much you plan on heating it and how long you plan on keeping it.

Okay. You've all got me thinking. Thanks!

First of all, spray foam is out. It is out based on cost but it is especially out because I am going to do this in stages over time.

It is not a barn in the farm sense. More like a very large garage (30' x 40' x 12') and I want finished walls.

Maybe I need to be disabused of my first thoughts on how to install rigid foam. I was going to cut pieces to fit between the stringers, and mount my interior wall material directly to the stringers. (Stringers? Is that the right name for the horizontal 2x6s the metal exterior is nailed to?)

Would I be better off to mount the foam board over the face of the stringers and the interior wall material directly on top of the foam board? That would leave a big air gap between the insulation and the exterior metal. That seems like an inviting space for all sorts of vermin, doesn't it? But it might make a firmer wall.

Use the Dow board, cut it to fit tightly, tape it with Tyvek tape, cover with FRP panels. You have the right idea. You can glue the FRP panels to the Dow board to keep them tight. You will want some mechanical connection to the barn, however.

The foam board insulation at R6 isn't much insulation. You may not notice a big difference. It helps if you can have a space of dead air between the R6 and the outside walls though.

R6 ain't squat...

Barndaminum finish it... build a 2x4 wall, fill wiht R30ish glass batt....

Who said you had to spray it all at once. I am doing my house now in stages. $1.10 sqft closed cell 2" thick. Save up, do an area. You will never get any of the processes you talk of now to be anywhere near as airtight as spray foam and if you can't keep it airtight, you are wasting your heating/cooling dollars.

No one has mentioned (or I missed it) blown in cellulose insulation. It is treated to be fire retardant and bug retardant. I can't speak to the price, but the big box stores let you use/rent a blower when you buy insulation from them. Said to be a great insulator. miles

Dennis, Are you agreeing with putting the Dow board between the stringers or over them? By mechanical connection, are you meaning something other than taping the stringer/Dow Board joints?

Rost, et al, Yeah, R6 ain't much. But I won't be in there much, if at all, in the winter. This won't be heated unless I am forced to work on one of the cars or something, in which case the heat will be a woodstove. Alleviating the solar oven effect in the summer is as big of a concern as heating.

The gun room will be heated but I'm looking for a way to control the temp to only stay a few degrees above the rest of the barn to keep condensation out. I figure that's the same principle as a Golden Rod or light bulb in a safe.

How much waste will you have with the cut-to-fit panels? Figure that in the price as well.

I'd have someone squirt an inch (or more) of urethane on the walls then paint it. You can then spray latex or most of the guys have some good coating options.

You won't beat the spray-on for dollars per R-value. The initial cost can be a shocker but either pay now or pay forever. 3/8"-1/2" sprayed on will blow R6 panels out of the water.

Can't beat spray on foam. Putting in R6 insulation is like scratching a pimple on an elephant's butt. You might think you are doing something but the elephant can't feel it.

A stated above,you can do the spray in increments.

Years ago we had a bunch of shops burn down around here. It happened when spray insulation caught fire, usually from welding sparks. It would almost explode and whoever was inside would have to sprint for the nearest door. Not all of them made it out. They've long since solved the problem by special fireproof paints to cover the foam but it was pretty scary at the time.

Having at one time worked for a big chemical company, I know just enough about urethane and similar products to be concerned about deadly fumes in case of fire.

Maybe somebody here knows more than I about this, but I personally would avoid it for that reason.

Ironbender has it nailed here. The rigidity of the foam is more than enough with out putting up panels. Want it brighter paint it white. Just doesn't get any better. Get a descent R value when you actually spray, at least 15 more depending on where you live. If you are in a tornado area the rigidity of the foam will help a LOT.

For those not in the know, there are building codes these days. You have to limit flame spread and smoke ... whats the word... i swear I'm getting old... producing smoke...

Anyway while things used to be one way I'd find it hard to believe that any new foam out there would not adhere to residential/commercial flame spread/smoke production guides. Its noted on every plan I review in podunk USA.

There is even fire rated spray on foam now... FWIW Meaning not only will it not burn much, it'll be so slow in trying to burn it will net you an X hour fire rating.

Between the stringers. Get whatever thickness it takes to fill the void.


I say this because you can do all of this yourself. Spray on foam is crazy expensive but very good.

For those not in the know there are PLENTY of places in northern MN and WI, and I'm sure others, that there aren't any building codes.

A good friend of mine just finished building a $300K "cabin" in central MN that didn't have any codes and it's on a populated recreational lake... in a town.

They may not REQUIRE building permits in certain, non populated areas but there are building codes everywhere. The US has gone generally to the IBC. International Building Codes. Now, even if the area you are in doesn't require a permit the products you use will still meet codes because generally speaking those are the products used where building permits are required.

Idaho County has no building code...........

That means, not inspected......

Yes, that is how it is in many areas here.

I have a 30x30 pole building that I use as my hunting cabin in the Upper Peninsula of Michigan; the floor joists are about 3' off the ground and it is metal sided. Every contractor / builder that I asked said to spray it with foam - it would both insulate and seal the cabin. I was up there in November deer hunting. The night before I left I let the wood stove burn out (about 10:00) and decided to just use the propane heater if needed. The inside of the cabin was about 75 when the stove went cold. It got down to about 5 degrees that night and never more than 30 the next day. At 6:30 the next night as I was closing the door to leave, the inside of the cabin was at 58 - and I had never even lit the pilot on the heater. Couldn't believe how well it held heat. I've also checked and not been able to find a draft anywhere when the wind has been gusting to 35 MPH. Cost to spray 6" in the walls, 16" in the ceiling and 6" underneath was about $5,000 as I recall.

You can save some cost by not spraying full thickness (didn't catch if wall thickness was mentioned). You can have the contractor spray to the "R: value (foam thickness) that you want.

Maybe more in the gun room area; maybe less in the barn/work area.

If y'all didn't read below.... the point was,as another noted, there is generally no reason to make things that don't meet code as there are very few places where they are allowed anymore...

Hence if it has to be X to meet code I'd bet 95% of things meet code these days...

Whether permitted, inspected etc.... by that I'm saying products.

What folks do labor wise is a total joke, I've seen a LOT of contractors build one way inspected and totally sloppy junk when not inspected but thats human nature these days.

But most of the physical products have to and do meet minimal codes.

BTW Texas and many otgher states adopted IBC stuff some years back, not always enforced in rural areas but is supposed to be. Not that it matters. Just a tidbit for those that think rural is always less restrictive.

But like I've told a few I inspected that complained, its why I live in the country, I'd tell myself to take my books and shove em...

Where IBC comes into play is when you buy Insurance, or when you decide you want to sell your property getting better loans etc. Too many people ignore permitting or at least inspections to their detriment down the road. Just call your insurance agent and ask him.

Keeping the heat in/ keep the wind out. An inch of closed cell or a couple of inches of open cell will make all the difference in the world. The foam seals up and keeps air out like nothing else. Hard Foam board or batting and tape cannot even come close.

Nobody is arguing that the spray foam is not the best. I am simply suggesting that he can make do with Dow board which is what his ceiling is insulated with. He can get the FRP panels free. Obviously he is trying to stay in a budget here.

I sprayed my the underside of my roof deck with foam on the last house I built (2009). I didn't insulate the attic. It was a wonderful system but cost me over $20K just for the roof. This was with open cell water born insulation. Closed cell urethane was a little higher R-value, had a structural component to it and more than double the cost.

I was suggesting a way to perhaps get the best of both worlds. Get spray foam AND limit ins. thickness to same some $.

Everyone is free to do what they want. For now.

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0 bummer ain't gone yet.

20K must have been a huge house.

There is little point in "insulating" with R6 versus spray foam. In the end, it will be almost completely wasted money and time.

Either do the spray foam, or leave it alone.

I insulated a south facing metal garage door on a 2 car garage with blue board and it made a HUGE difference in both summer and winter. It was an oven in the summer before and not nearly as bad after.

No, not hardly, foam is just expensive! I think my roof was about 45 squares.