Insulating Metal Siding

[beweir]

I have a metal sided pole barn with an 2 story apartment that I'm gutting in Central NY. The previous owner had fiberglass insulation some ext walls had a vapor barrier- some none. I tore most of the Fiberglass insulation out- mice had made mess of it- I notice alot of sweating on the metal when I heat it up while working there in the cold- there's 7 inches between the metal and inside of where the vapor barrier would be (toward the warm) so I would have a 1" air barrier to keep the fiberglass from getting saturated- however I'm leaning towards closed cell foam for 2 reasons 1. More Mice proof and 2. If thick enough would prevent condensation or sweating- was thinking about 3 inches?. I have slight reservation because of the cost and also this would put my vapor barrier on the outside wall, the inside wall will be drywall. Is there any problem with having the vapor barrier on the outside wall- the metal is a vapor barrier anyways and then finishing off the studs with regular drywall?

 

[rd_macgregor]

My understanding is that you want to keep the moisture from entering the wall in the first place, so the vapor barrier goes on the inside. You can put a heavy plastic over the wall before putting up the sheetrock. Calk around any electrical outlets and use foam outlet seals under the cover plates to minimize air leakage there. Another alternative would be to leave a ventilated air gap between the insulation and the metal wall (if you use foam, not with loose fill or batts). An air gap would let any moisture moving through the wall evaporate rather than be held against the metal, where it would, eventually, rust out your walls.

BOB

 

[beweir]

The air gap is also the cause of moisture? Warmer air against the cold metal? I was hoping that the foam would prevent the condensation from occurring period- the moisture in the air would travel thru the inside wall though. Any Spray Foam advocates around?

 

[firemech]

Love the spray foam but get out the wallet if you're going that way. I have a 60x200 ft building with 12 ft high walls. Spray foam is almost six times the price of shiplap 2" thick SM board. The spray foam would definitely be easier to get around corners and crevises but I just can't see me spending the difference. Haven't committed to anything yet it might just stay unheated!
firemech

 

[bdeboer]

I have a metal sided pole barn with an 2 story apartment that I'm gutting in Central NY. The previous owner had fiberglass insulation some ext walls had a vapor barrier- some none. I tore most of the Fiberglass insulation out- mice had made mess of it- I notice alot of sweating on the metal when I heat it up while working there in the cold- there's 7 inches between the metal and inside of where the vapor barrier would be (toward the warm) so I would have a 1" air barrier to keep the fiberglass from getting saturated- however I'm leaning towards closed cell foam for 2 reasons 1. More Mice proof and 2. If thick enough would prevent condensation or sweating- was thinking about 3 inches?. I have slight reservation because of the cost and also this would put my vapor barrier on the outside wall, the inside wall will be drywall. Is there any problem with having the vapor barrier on the outside wall- the metal is a vapor barrier anyways and then finishing off the studs with regular drywall?

Another option would be a foam board layer between the fiberglass and metal. You want to caulk the edges to prevent air flow.

Or DIY foam like Tiger Foam if the area is not huge.

 

[PILOON]

The inside is where the vapor barrier goes!
And it wants to be sealed with VENTURE tape.
If well sealed then no vapor will get to the insulation.
Otherwise stated, you want the building to be one big plastic bag. LOL

All that aside, it is hard to get perfection so something to keep the wool from touching the metal siding might be a good idea.
That something should breathe, like house wrap (Tyvex).
Also you could probably use some felt paper or anything that creates a slight gap between the metal and the wool insulation.
If it weren't so pricey I'd suggest something like the moulded eave vents (Styrovent) as the ideal spacer.

Mind U with tapes U could probably be able to hang the house wrap B4 placing the wool in place.
Also U want that wool to be real snug, so much so that it would stand up without any supports.

NEVER vapor barrier on outside wall!
That will guarantee wet soggy wool and mould formation on backside of drywall.
(I have seen rotted studs created from that)

Inside=airtight, outside=breathable

 

[magicheater]

I use 1.5" foam against the metal with added fiberglass beneath that and have had great success. My roofs are "hot roofs" but they do just fine.

 

[toy]

The inside is where the vapor barrier goes!
And it wants to be sealed with VENTURE tape.
If well sealed then no vapor will get to the insulation.
Otherwise stated, you want the building to be one big plastic bag. LOL

All that aside, it is hard to get perfection so something to keep the wool from touching the metal siding might be a good idea.
That something should breathe, like house wrap (Tyvex).
Also you could probably use some felt paper or anything that creates a slight gap between the metal and the wool insulation.
If it weren't so pricey I'd suggest something like the moulded eave vents (Styrovent) as the ideal spacer.

Mind U with tapes U could probably be able to hang the house wrap B4 placing the wool in place.
Also U want that wool to be real snug, so much so that it would stand up without any supports.

NEVER vapor barrier on outside wall!
That will guarantee wet soggy wool and mould formation on backside of drywall.
(I have seen rotted studs created from that)

Inside=airtight, outside=breathable

What is your opinion of using a heavy plastic that is long enough to reach from the ceiling to the floor doubled, put one layer of the plastic against the metal and then the fiberglass insulation, and then fold the plastic at the bottom and bring it up and back to the ceiling? That way your insulation has a vapor barrier on both sides of your insulation and then use the blue board on the inside of the building and then put plywood over that. I am hoping that will stop the condensation since there is no air flow going in either direction and it should stop the heat from the inside of the building from hitting the metal on the outside of the wall.

My Dad always advised against getting a metal building and I am finally beginning to agree with him.

Another thing that I was thinking about, a few years ago the going thing was aluminum siding and aluminum clad windows and then they decided that was the dumbest idea ever because of the temprature transfer of metal, now they will give you an energy tax credit for using metal on your house, what has changed?

 

[magicheater]

What is your opinion of using a heavy plastic that is long enough to reach from the ceiling to the floor doubled, put one layer of the plastic against the metal and then the fiberglass insulation, and then fold the plastic at the bottom and bring it up and back to the ceiling? That way your insulation has a vapor barrier on both sides of your insulation and then use the blue board on the inside of the building and then put plywood over that. I am hoping that will stop the condensation since there is no air flow going in either direction and it should stop the heat from the inside of the building from hitting the metal on the outside of the wall.

My Dad always advised against getting a metal building and I am finally beginning to agree with him.

Another thing that I was thinking about, a few years ago the going thing was aluminum siding and aluminum clad windows and then they decided that was the dumbest idea ever because of the temprature transfer of metal, now they will give you an energy tax credit for using metal on your house, what has changed?

Bad idea if you will be heating the building. Double vapor barriers are bad news.

 

[PILOON]

Bad idea if you will be heating the building. Double vapor barriers are bad news.

Generally I'd agree, however I notice that in commercial metal buildings the insulation used is like a big blanket whereby the insulation is in fact double vapor barrier clad wool insulation.
HOWEVER, THOSE BLANKETS ARE TOTALLY HEAT SEALED.

One solution might be a foil clad vapor barrier that incorporated a laminated bubble wrap type of insulation. Product is a mere 3/8" and claims R20.

One winter I completed a house but purposely did not vapor barrier a 4' section as there was to be an addition to add there.
That 4" section was super chilly and when I removed the wool I discovered that 3/4 of the wool was all ice and frost.
That was sure and eye opener to me.

Another job where the owner used foam board outside and wool inside without barrier was a real disaster.
All his studs were so rotted that we had to replace them one by one, including base plates.
AND that was a 2 story building that should have been a tear down but because of bylaws and setbacks we had no option but to repair and replace as required.

The foam acted as a barrier and the wool became a sponge! Every stud was black and soggy. A wonder that it did not collapse from snow loads.
And the gyprock was mostly mush!

Ask me why I am so sold on well sealed vapor barrier!