Insulation WET when heating the shop.

[chopperimpala]

I KNOW it is summer but figured it would be easier to fix this NOW while it is warm.
I have the typical pole building, metal siding, 6X6 posts 10 feet apart, with horizontal 2x6 stringers between the posts spaced on 30" centers vertically going up on 14 foot walls. The insulation consists of, 4mil vapor barrier on the stringers, vertical hanging fiberglass bats and 4mil vapor barrier over them, and then 3/8" OSB.
The reason I went with the vapor barrier in front AND behind the batts, was because on my last shop I had, that was insulated the fiberglass would freeze to the steel siding. I thought this way I would prevent that.
Last year when heating my pole building (30X36) I discovered the insulation was WET on the metal siding side. This was the first winter I had insulation up and heat in it (propane reddy heater, and a wood stove).
So what needs to be done? I have talked to several people... Lowes, H.D., and the builder of the shop, and the only answer other than a "blank stare" was "use the styrofoam insulation". Since I have quite a bit of money invested in insulation, 2X4's, and OSB, I am not really wanting to tear all that down and put up the styrofoam. Comments, suggestions, need more info???
Thanks, Ken

 

[Warrenator]

I think your propane reddy heater is putting out lots of moisture, which is migrating to the cold siding and condensing. Perhaps just heat with the vented wood stove, or switch to a vented style heater. Propane puts out a lot of water when it burns.

 

[chopperimpala]

Thanks, I knew Propane put out "some moisture" but have no idea really how much. Also, not that it makes a difference but I typed in the wrong heater I was using... I forgot, this past year I bought a Mr. Heater: Convection Heater Model No: MH200CV. STILL a propane heater but doesn't run off electricity like my Reddy heater did, and it puts out 75,000 - 200,000 BTU/HR, versus the 80,000 total of the Reddy heater.
Thanks again for the info. Ken

 

[jimp]

The first year I had my shop, I heated it with a 250,000 BTU convection heater, it rained all winter inside the shop, mold every where. The next year I had central heating installed, no more rain or mold.

Non vented propane adds a lot of moisture.

 

[burleymike]

IIRC you will get 1 gallon of water for every 5 gallons of propane burned. I would bet my money on the propane heater causing the condensation.

 

[tatra]

use a dehmidifier..........bonus is it generates a dry heat...........

 

[chopperimpala]

IIRC you will get 1 gallon of water for every 5 gallons of propane burned. I would bet my money on the propane heater causing the condensation.

You seriously get 1 full gallon of water in the air for every 5 burned!?!?!? I had no idea
My woodstove doesn't work real good, so I run that heater almost full blast NON-STOP when I am out there and I have 3 of those tall 100 lbs. tanks (hell I am from San Diego but live in Spokane and HATE cold!!!) so I never run out, local compressed gas shop fills me up bi-weekly at my work when they swap out our welding argon and helium tanks. I must be FLOODING the shop!!! It is well vented so no worries of to much exhaust!
but man the water in the air!!! That has to be it!?!?!?

 

[hockey88fan]

Does having the vapor barrier on the outside, as well as the inside, contribute to his problem as well? I would think the outside of the building needs to breathe, I'm no expert mind you.

 

[kbs2244]

You got to go with a vented heater.
Yes 1 gal from 5 is a good working number.
It is worse with karosene.
Your wood stove should help some since it is vented, and uses inside air for combustion.

 

[Dragster Racer]

Does having the vapor barrier on the outside, as well as the inside, contribute to his problem as well? I would think the outside of the building needs to breathe,

I would say this is part of the problem and the unvented heater is the other part.

 

[chopperimpala]

The inner vapor barrier is "liquid nails" glued to the 6X6 posts, top horizontal wall stringer, and floor, basically a 12'X14' square sheet of plastic glued all around between the posts, (I used liquid nails 'cause I got 5 cases from work free). The metal siding is that "corrugated" style so from the 3" gap between the earth and the bottom of the siding and then the top of the siding has a 2" gap between it and the roof eaves, lots of air can flow thru those corrugated channels, I --think??-- I have plenty of breathing. But not sure?

 

[redcorvetteman3]

not to hi jack this thread but what about radiant heater? Natural gas? my land lord put 6 -200,000 btu's in a pole barn and it was raining inside and 100 degres at the ceiling. He turned off two heaters and everything was back to normal. The ceilings are 20ft high. Would these do the same thing as the propane no venting?

 

[6768rogues]

I believe that the correct number is that one gallon of propane burning produces .81 gallon of water. Hence, almost a 5:4 ratio, burn 5 gallons of propane and get a little over 4 gallons of water as a byproduct of that combustion.
On the other hand, diesel produces 1.05 gallons of water for every gallon of diesel burned.

 

[Steve in Mi]

Double moisture barrier (POLY) is a NO NO. Only one moisture barrier and that needs to be on the warm side of the insulation. As already said, an unvented propane heater is the other flaw in your plan for comfort.

 

[chopperimpala]

^ got it, so If I remove the barrier from the metal siding side what keeps the insulation from gettin wet with the condensation transfering from the outside of the siding to the inside? I had my insulation freezing to the siding at my old house when I had just insulation, a vapor barrier on the "warm" side, drywall, and used a woodstove. The way I found this out was I slid into the wall (snow and ice on the damn ground) one day, so I was replacing a portion of the siding and when I removed it a layer of insulation pulled off with it because the insulation was frozen to the siding. Hell maybe it is just me and that is the way it is supposed to be and I am just "over-thinking" it all?!?!?!?!

----AND PLEASE....DON'T GET ME WRONG here guys anything I say and ask is NOT in a sarcastic smart-*** way EVEN if it seems that way, I am the type of guy that if I don't understand it, I'll ask! I don't care if someone thinks it is a dumb question! If I don't know then I ask so I will know!!!!---

 

[Steve in Mi]

The moisture to keep out of the insulation comes from inside the structure, that is why the poly goes on the warm side. Your observation of insulation frozen to the outside metal siding can have I think a few different scenarios - I'll just say that wet fiberglass has little to no insulation value. Temperature changes (cycling with passing clouds) in the sheetmetal skin from the Sun beating on it to a cooler cloud cover condition and viceversa can lead to water condencing out on the metal surface - in Winter the water can take on the form of ice. Your idea of keeping the insulation away from wet/icy metal is a good one but the execution using poly moisture barrier was not. Better to have used window screen, something to hold the fiberglass back but still allow the wall to breathe. I personally think TYVEK is a great product for this. It will stop liquid water but allow water vapor to pass, thus the wall can breathe but w/o the presence of drafts.

It might be easier to remove the metal skin to get at the poly if you decide to attempt a fix.

 

[Kriilin]

Propane heat: C3H8 + 5-O2 = 3-CO2 + 4-H20 + heat

 

[BadgerBoilerMN]

It is better to go without a vapor barrier than to sandwich wall insulation between two as you can see, once wet they can't breathe.

If you use 2# foam no problem. If you use fiberglass the ribs on the outside steel have to have air flow. Steel building can be very air-tight and all combustion equipment should be sealed combustion and direct vent. The tighter the construction the more critical this point.

If you have an exhaust fan you have to also consider where the makeup air will come from.

 

[dlenkewich]

Does having the vapor barrier on the outside, as well as the inside, contribute to his problem as well? I would think the outside of the building needs to breathe, I'm no expert mind you.

There should be vapour barrier to the warm side only. With both sides vapour barrier'd, you're trapping air, the air turns to condensation.

If you're insulation was freezing to the siding, you either had a leak, or a heat loss causing condensation on the cold side. The heat loss could have been attributed to inadequate insulation, insulation gap, broken seal, tear in the vapour barrier...

It shouldn't have to do with your heater. If you heater is putting out moisture, it shouldn't be getting past your vapour barrier, which means you'd have condensation and/or mold on the warm side of your vapour barrier.

Also - Don't know about your codes, but everything I've seen usually calls for a 6mil or better.

 

[GSSFC]

There should be vapour barrier to the warm side only. With both sides vapour barrier'd, you're trapping air, the air turns to condensation.

If you're insulation was freezing to the siding, you either had a leak, or a heat loss causing condensation on the cold side. The heat loss could have been attributed to inadequate insulation, insulation gap, broken seal, tear in the vapour barrier...

It shouldn't have to do with your heater. If you heater is putting out moisture, it shouldn't be getting past your vapour barrier, which means you'd have condensation and/or mold on the warm side of your vapour barrier.

Also - Don't know about your codes, but everything I've seen usually calls for a 6mil or better.

A vapor barrier with thousands of holes from staples and screws is no longer a vapor barrier.

Tim

 

[rwreuter]

How about this folks...........

my house faces the north (i live in Kansas = WINDY) here is what i did to the north wall (exterior is brick):

installed faced bats (R15) then on top of the faced bats i installed 1" of expandable polystyrene foam insulating with sheathing (R3.85). i liquid nailed the styrene to the 2x4's and at all of the joints. THEN over the top of the polystryene i installed 5/8 OSB. at a later date i will seal all of the joints and paint it.

the garage currently isn't heated, though more than likely i will be buying a convection 30k-80k convection propane heater. it won't be used all the time, just now and then for short periods if i want to do some work.

does anyone foresee any problems with this set up....i know now is a little late to ask this but, but oh well....

 

[rwreuter]

no one would even venture a guess at any moisture issues?