Tyvek or no?

[rburke65]

Getting closer to pulling the trigger on a 32'x56'x12 garage with OSB sheeting then steel siding. Looking to hear opinions on the pros and cons on the need of Tyvek type of house wrap under the metal siding. It will be insulated. And, what about using something similar on the roof, over the OSB roof sheeting and under the metal roofing? Thanks everyone.

 

[bhclark]

If you're insulating, then you need the Tyvek as a second vapor barrier as well as stopping the wind/water from getting through. It's standard building practice.

They also make a new OSB that has the barrier built into the outer surface, then you just tape the joints.

 

[toyotadriver]

I would highly recommend using double bubble or single bubble foil under the metal.

 

[jkuro]

Tyvek is not a vapor barrier but it will stop wind and moisture if applied properly with seams taped per manufactures instructions.
Heres the link:
http://www2.dupont.com/Tyvek/en_US/uses_apps/apps_landing.html

 

[anotheroldguy]

I would highly recommend using double bubble or single bubble foil under the metal.

If the bubble is alum foil, won't it react with the steel? If it's tin (steel) it shouldn't matter. Right?

 

[brownbagg]

tar paper works good too

 

[dirttracker18]

Yes, a necessary step to protect your osb.

As noted already it is NOT a vapor barrier.

 

[red]

Getting closer to pulling the trigger on a 32'x56'x12 garage with OSB sheeting then steel siding. Looking to hear opinions on the pros and cons on the need of Tyvek type of house wrap under the metal siding. It will be insulated. And, what about using something similar on the roof, over the OSB roof sheeting and under the metal roofing? Thanks everyone.

I installed tyvek on my garage, and was disappointed when on a windy day before the vinyl was finished and I felt the wind blowing thru the "vapor barrier". I promptedly caulked all the joints/cracks in the plywood (from the inside).

Ironically I fought with the modular company, that buildt my house, on a vapor barrier and they insisted it wasn't necessary because they caulked the plywood before installing the siding. They installed the vapor barrier because I sent them a copy of the local building code that required it. I would in the future use 30lb roofing (tar) paper.

 

[toyotadriver]

If the bubble is alum foil, won't it react with the steel? If it's tin (steel) it shouldn't matter. Right?

There is no reaction. I'm not sure what the actual material is but there is no reaction.

 

[dirttracker18]

I installed tyvek on my garage, and was disappointed when on a windy day before the vinyl was finished and I felt the wind blowing thru the "vapor barrier". I promptedly caulked all the joints/cracks in the plywood (from the inside).

Ironically I fought with the modular company, that buildt my house, on a vapor barrier and they insisted it wasn't necessary because they caulked the plywood before installing the siding. They installed the vapor barrier because I sent them a copy of the local building code that required it. I would in the future use 30lb roofing (tar) paper.

Once again, house wrap is not a vapor barrier. That's why you felt the wind through it. It protects your sheathing.

 

[Al Bundy]

I've always used Typar. Tyvek breaks down when exposed to light. After a few years it loses a lot of it's effectiveness.

 

[dirttracker18]

I've always used Typar. Tyvek breaks down when exposed to light. After a few years it loses a lot of it's effectiveness.

None of the house wraps are meant to be exposed to sunlight for any length of time.

 

[tdkkart]

A friend recently pulled all the vinyl siding off his house and re-sided it simply because it didn't have Tyvek under the siding.

I told him he was nucking-futs.

Prior to about 15 years ago you never saw Tyvek or any kind of wrap over the exterior sheeting, those houses are still standing.
It's not a bad idea, but I sure as hell wouldn't rip all my siding off to put it on.

 

[rsa]

From the Green Building Advisor: All about Water Resistive Barriers.

 

[Al Bundy]

A friend recently pulled all the vinyl siding off his house and re-sided it simply because it didn't have Tyvek under the siding.

I told him he was nucking-futs.

Prior to about 15 years ago you never saw Tyvek or any kind of wrap over the exterior sheeting, those houses are still standing.
It's not a bad idea, but I sure as hell wouldn't rip all my siding off to put it on.

I agree that your friend went a bit overboard. But keep in mind 40 years ago they didn't insulate most houses. Yes they are still standing too. But I wouldn't want to heat one.

 

[rsa]

...keep in mind 40 years ago they didn't insulate most houses. Yes they are still standing too. But I wouldn't want to heat one.

40 years ago was only 1971. Hard to imagine a majority of houses not being insulated. Poorly insulated, yes; not insulated, no.

My modest, rural home was built in 1949 and used asphalt felt as the water resistive barrier, rock wool batts in the walls and attic.

 

[rsa]

I would highly recommend using double bubble or single bubble foil under the metal.

What's that cost? About $0.50 a square foot at Lowes? Likely less expensive in bulk.

I'd much rather put the same money toward taped rigid exterior foam sheathing. 1" XPS is also about $0.50 per square foot for R-5 (the code minimum R-Value for exterior foam sheathing in the OP's climate zone—see Calculating the Minimum Thickness of Rigid Foam Sheathing. Besides the honest R-5, XPS resists inward solar driven moisture (if you use a reservoir cladding) and provides a thermal break.

See also: Radiant Barriers: A Solution in Search of a Problem.

 

[BillK]

R,
What does the manufacturer of the metal siding recommend ? That would be the first place I would be looking.

 

[clayton]

What I find is funny is after you wrap your house with it you drive nails through it destroying the barrier you were trying to correct.

 

[rburke65]

Do I need......orcwant, a WRB under the roofing metal?

 

[MustangRick]

What I find is funny is after you wrap your house with it you drive nails through it destroying the barrier you were trying to correct.

I 100% agree. You see shows on TV where they spend hours taping every little nick and hole in it then nail the siding on with thousands of nails.

 

[Falcon67]

I don't know when my grandfather built his shop buildings, but they had been there a while when I was a kid, so thats...hell with that. OK, more than 50. They all had tar paper under the skin. The house I grew up in used it and I used it when I stripped the siding and insulated the last house. When I cut into the addition on the back of that house to insulate, I found tar paper in good condition. The addition would have been done sometime in the 70s. The wall cavities behind the paper were pretty clean, unlike the 1926 sided portion of the house that had nothing under the siding.

It's pretty dry here, and the new shop will be getting 15 lb felt under the siding, no exterior OSB. And as noted, there will be no taping or sealing. Just will overlap the rows and wrap a little around the corners (doing one wall at a time). It'll have plenty of #6 galvanized penetrations - no need to get carried away LOL. And I like the cost - $18 a roll, total needed for my 24x40 is 3 rolls.

 

[speed bump]

Tyvek is designed to be a breathable vapor barrier for your walls. You put plastic on the interior and Tyvek on the exterior so that the moisture can escape otherwise given the right temperature gradient in your wall you will get ice to form inside the wall.

As far as the roof you could use felt but after I used a product called Titanium on my last roof I can't see ever using felt again. Much nicer to work with, doesn't rip, and comes out at slightly cheaper than 30lb felt.