Insulating a metal building

TBone · Oct 22, 2003

Hi folks. I am in the process of building a 28 X 36 X 10 workshop and need some advice on insulating it. I need some insulation mostly for the condensation problems associated with metal clad buildings, not so much for the heat and cold, even though it does get hot as blazes down here.

It will be stick built on a concrete slab (which I've already poured) with 26 ga galvalume on top and sides. I plan on using 3/4" styrofoam board (Dow blue board) on the sides (under the metal)and that should go on fast and easy.

The roof is a different matter. I don't really want to put the 4 X 8 boards over the purlins. I'm afraid I'll step through it while putting down the metal roof. /forums/images/graemlins/shocked.gif /forums/images/graemlins/shocked.gif The trusses will be on 4' centers and I had planned on putting the purlins about 30" apart. I could cut the styrofoam and put between the purlins but that would be a major pain. /forums/images/graemlins/mad.gif

I had thought about "sealing" the ceiling from below with the styrofoam board and not having any insulation in the roof area. Would I still get condensation from the metal roof? If I do it would drip down on my "styrofoam ceiling" and that probably wouldn't be a good thing. /forums/images/graemlins/shocked.gif

I really didn't want to use roll insulation but that might be my only option. I sure as heck can't afford to spray the ceiling. /forums/images/graemlins/confused.gif

Any suggestions would be greatly appreciated.

TBone

CTyler · Oct 22, 2003

I used roll insulation with the reflective backing for the roof and sides. This went between the wood and the metal.

If you going to put a ceiling in it then you'll need to vent the attic space above the trusses. If you don't it will sweat and drip. You'll need to plan how to vent it. I don't know how you calculate the required vent space though. I'm sure there is a formula out there if you search for it.

The general rule is you vent or insulate. I.E. vent the uninsulated space.

One more comment.....

If you insulate to the rafters themselves then you'll need to leave a space at each end for venting. A foot I think, not 100% positive. This is becuase there will be an uninsulated space between the rafter and metal so it has to be vented.

gsganzer · Oct 22, 2003

Go with the rolled insulation. When I hear styrofoam, I think fire hazard (remember the nightclub in Rhode Island?). If you do any welding, I wouldn't want styrofoam anywhere around.

My place had a 30' x 40' shop on it when I bought it. Unfortunately, the previous owner didn't have it insulated. I live in N. Texas and you need the insulation for both the summer and winter. In the summer you can feel the heat coming off the metal 5 feet away (feels like you're in an oven). In the winter, I have to keep the salamander heater aimed right where I'm working. As soon as I turn the heater off, it gets cold. No heat retention without insulation. Not to mention the sweating/condensate problem you referred to.

I priced up some roll insulation for the walls and roof and it will cost about $800.00 This was for the vinyl backed 2" thick rolls with seam tape. It's real easy to put on a new building. You just roll it out and tape it to the framework, then put your sheets over it.

I'm trying to figure out how to insulate my existing building with it. The only way to do it right is to remove the sheets, roll out the insulation and lay the sheets back down. (PITA)

I don't think I'd build a metal building without insulating it, but I'd find something that's non-flammable. Regardless of the climate.

CTyler · Oct 22, 2003

( I'm trying to figure out how to insulate my existing building with it. The only way to do it right is to remove the sheets, roll out the insulation and lay the sheets back down. (PITA) )

That would be a major chore! Is there any room to squirt foam between the wood and metal? Maybe you could push up on the metal and see, not sure. The other thing might be to spray it along those places and roll out the rest.

gsganzer · Oct 22, 2003

There's no wood. The structure's made of welded pipe w/ r-panels. My other option is to insulate it from the inside by rolling out the insulation and holding it in place with chicken wire. I'd probably have to weld on some wire studs in a few places to hold the wire. I'm still trying to figure out my best option. I have a few other projects before I tackle this one, so I already planned on freezing for another winter.

RedDog · Oct 22, 2003

I would use the same stuff on the roof. It is easy to put on, just look at your nail heads when stepping.

I'm doing my barn now.

Good luck, RedDog Kioti DK65

Junkman · Oct 22, 2003

( Go with the rolled insulation. When I hear Styrofoam, I think fire hazard (remember the nightclub in Rhode Island?). If you do any welding, I wouldn't want Styrofoam anywhere around. ...............................................
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I don't think I'd build a metal building without insulating it, but I'd find something that's non-flammable. Regardless of the climate. )

The fire in R.I. was a flammable product that wasn't installed according to the manufacturers specifications. There are spray foam insulation that is approved for building use and is very safe. Almost all insulation instructions tell you that it MUST be covered to be safe. The paper or plastic on fiberglass insulation can also burn. As with most products, if they aren't used properly with regard to the manufacturers recommendations, there is always a chance of fire or other safety related problems. If you are interested in safety, then use fire code sheet rock to cover what ever you insulate the walls with..

BB_TX · Oct 23, 2003

I put up a 30'x40'x10' metal building a little over 3 years ago. I bought a prefab building kit with an insulation option. The insulation came in rolls 6' wide precut to length to go from eave to eave. I just rolled out the insulation from one eave to the other, layed the metal sheets on it, and screwed them down. worked out great. The insulation was backed by a nylon (?) reinforced white vinyl backing. Picture attached.

slowzuki · Oct 23, 2003

Check out Quonset hut insulation packages, they are intended to be installed from the inside. I have never seen exactly how they do it though. May be a stud welder or something.
Ken

TBone · Oct 24, 2003

Hey, thanks for all the ideas. I have been looking around this area for a roll insulation with a tough face of some sort but have not been successful in finding any. All the building supplies have are the 15" or 23" rolls (3 1/2" thick and up) that go between studs and ceiling joists. The metal building companies are not really interested in selling me anything less than a finished building.

As far as the flammability of the foam board that doesn't worry me too much. I insulated a little building with it that my wife uses for her craft projects. I does a pretty good job. even in the hot months a small window ac keeps it cool.

I took a piece of scrap and put a torch to it and it really doesn't burn - it melts. A fire would easily consume it but it doesn't provide much of a fuel source in itself.

If I decide to use it I will probably build me a small welding booth in one corner and cover the foam board with a non flammable material.

Anyway thanks again for the suggestions. I haven't even started framing yet so I am still flexible in my planning.

TBone