Ceiling Installation

[gmhill33]

Greeting,

I want to insulate my roof, metal roof. My question is, what would be the best to use? The trusses are 4' on center and I don't have the foil paper under the metal. I plan on putting some kind of plastic vapor barrier under the drywall.


Thanks,
Gary

 

[Shocker]

Spray foam would probably be the best option.

 

[gmhill33]

Spray foam would probably be the best option.

Thank you sir.

Gary

 

[mebedave]

Spray foam would probably be the best option.

With all due respect to Shocker. I too have a tin sided building that I’m researching on how best to insulate walls and ceiling. I called Morton they told don’t use spray foam, it’s their experience it will over time rust out the tin do to water getting into the seams and trapped between the tin and the spray foam. I’m no expert myself and I’m still researching on how best to insulate and finish wall/ceiling. I’m just passing on what I have found. My dilemma is: do I wrap my post and back side of tin (from the inside) with a house wrap first and then install insulation following with a vapor barrier then finish wall/ceiling. One thing I no for sure the building must have very good ventilation, that tin will sweat!
Just my one cent

 

[gmhill33]

With all due respect to Shocker. I too have a tin sided building that I’m researching on how best to insulate walls and ceiling. I called Morton they told don’t use spray foam, it’s their experience it will over time rust out the tin do to water getting into the seams and trapped between the tin and the spray foam. I’m no expert myself and I’m still researching on how best to insulate and finish wall/ceiling. I’m just passing on what I have found. My dilemma is: do I wrap my post and back side of tin (from the inside) with a house wrap first and then install insulation following with a vapor barrier then finish wall/ceiling. One thing I no for sure the building must have very good ventilation, that tin will sweat!
Just my one cent

The sweating is the thing that worries me. I wish I would have done a little more research on the metal roof before i put it on. There is another thread that says if you put the house rap on the inside you HAVE to put it on backwards (with the lettering facing the outside).

Originally Posted by bobadame View Post
Krooser can you explain why covering a vapor barrier with a permeable barrier would cause moisture problems?

Tyvek is a waterproof membrane.... installed on the outside it will prevent water from penetrating the wall sheathing and causing damage... it will also allow a building to "breathe"... letting the moisture out of the walls.

If you install Tyvek INSIDE it will allow moisture from the outside of the building to migrate thru the walls and it will be trapped between the Tyvek and the interior sheathing...wallboard/plywood/OSB. Mold will build up on the inside of the interior wall covering.

If you install it on the inside BACKWARDS (the Tyvek name facing the wall) moisture will still be able to penetrate the outside wall but will not go thru the Tyvek...in that case it would act like traditional plastic sheeting.


I think Bob will be better off simply using plastic sheeting over the fiberglass batts... but it's best to tape all the seams and allow a little overlap to insure an air-tight seal. I'm not sure what the cost difference would be.

When I built my shop... post and beam construction with steel siding... I was going to wrap my walls with Tyvek. I had already sheathed the outside walls with 1" blue board with foil facing. My son-in-law jumped the gun and started installing the steel siding while I was at work. He got one whole wall and half a second wall done before I got home... the Tyvek was never installed but I did wrap the inside with plastic.
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www.symcoshakedown.com

Here is a link to that thread - Tyvek inside? and this is the one leading to it - how and why's of house wrap & vapor barrier


Assuming you haven't seen these threads.


Thanks for the info,
Gary