metal building and moisture??

kayssupply · Dec 11, 2004

The condensation forms when you have a 20degree change in temp betwwen two areas, barn and outside air. If the barn is cool and the outside gets warm faster the condensation will form. Venting while this is happening will make it worse. Venting all the time will make it less. Here in the midwest we have to vent our attics and crawl spaces in order to keep it down. If you can keep the inside of the barn close to ouside temp it shouldn't sweat. It can be hard on the cool nights and warm sunny mornings. Insulation helps keep the two temps apart. I have 1/4" of foam on my intire barn. It works great for the walls but you have to keep the doors closed until the inside warms up in order to keep the tools from sweating.

nobull1 · Dec 11, 2004

I agree you don't need the full 6" of insulation. In out area the cost of 6 instead of 4 is only a couple hundred dollars more so well worth the money. A couple of issues I have about the ridgid board that might even be non issues are 1 no vapor barrier so all the joints have to be tight to prevent air leakage.2 The air space you have to leave due to the design of the building might be a spot where condensation may build and run down behind the insulation to the floor. When you use the fiberglass insulation it conforms to the building and the vapor barrier has a 6" overlap to seal it tight. I have assumed that you have a building as mine which is corrugated every two feet to a depth of 6". After reading your post there is no reason to be sure of that and what I say might not be pertinent at all to your project. Do you have a pic of your building or able to at least tell us if the sides and roof of your building are flat or corrugated?

LBrown59 · Dec 11, 2004

there are wet spots on the floor from rain soaking the outside perimeter most of the time.
JASTN70D
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You need to slope the ground away from the base of the building to drain off surfice rain water.

JD3130 · Dec 11, 2004

Mine is what they call "V" Crimp. It is flat and has a "V" crimped in it on 10 inch centers. (The V is not really a V, as it has a 1" flat) but they call it that. Remember we don't have snow loads to deal with here in south TX. Mine is supported by purlins on 4 ft centers. Not as fancy as yours, as our temp range is only from 29 to 103 degrees.
PS.
The drainage is well sloped all around the building, the floor is sweating. That day my tractor was in the shop and it looked like I had just drove out the car wash. ( I should add, we had just had 10 of rain in 8 hours, so it was humid)

nobull1 · Dec 11, 2004

Don't think fancy is the word to use /forums/images/graemlins/grin.gif. I bought mine used tore it down moved it and rebuilt it.

sneaky_pete · Dec 11, 2004

( I agree you don't need the full 6" of insulation.)

Mine has only 2 or 3 inches of insulation at best, but I have never had any condensation inside. Even that much insulation makes a tremendous difference in the summer. The insulation is just roll stuff with a white plastic back that was put between the metal frame and the steel panels, including the roof. I put OSB over the bottom 8 feet; I don't know if that compressed the insulation more or trapped more air.

Darren · Dec 11, 2004

"I know the spray on insulation works, ..... But so far the DIY's can't do that."

You can do it yourself. There's several links in previous posts to manufacturers that provide the two part system. It doesn't seem difficult to do. It's also cheaper than hiring a contractor.

LBrown59 · Dec 17, 2004

You said the purloins on the roof trusses were spaced 4' on center.
What is the spacing of the roof trusses?

The trusses on my metal build are on 4' centers but the purloins on the trusses are on 2' centers.

LBrown59 · Dec 17, 2004

( 1* Remember we don't have snow loads to deal with here in south TX.
2*Mine is supported by purlins on 4 ft centers.

)
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1-2*
But you still have wend and by spreading the purloins from 2 foot centers to 4 foot centers you have fewer nails holding down the metal sheets.

Also I don't think I'd want to walk on it as 4' is a pretty wide gap to span with the metal sheeting.
Another thing with purloins at 4 feet rather than 2 feet you have fewer nails holding the roof down onto the trusses.
A good hard wend is more likely to lift off the entire roof with 4' purloins than it would be with 2 foot purloins.

JD3130 · Dec 18, 2004

Not a problem. We build these buildings all around here. They are engineered by the factory. In fact for my span they called for a 5' on center. but I decreased it to 4' because I like to over-kill everything. The mfg claims they are safe to walk on as long as you step on the flats and not the ribs. But since I weight 330LBs I stay on the purlins when I have to go up there. Their 6 inch purlins are designed to span 25 ft on 5 ft centers. If I remember right, the bldgs are rated for 175+ MPH winds. I always add extra ties etc. for my own peace of mind.
I deal with a place call "Metal Mart" near Shertz, TX I think they have a web site. I'll ask next time I'm up there.