Alternative vapor barrier

[Mr.wolf]

Gents,

Would this product be better or worse than tyvek? I need to start handing steel this weekend and I planned to put tyvek over the girts and steel right on that. I thought about using this instead. It's actually much cheaper. I have built this building by myself do to cost and time constraints. And I need to finish it fast. My only worry with this or tyvek is does it hold moisture against the steel? That would be bad I assume. I plan on insulating it with rolls later next year (maybe this winter if we ever get some snow!) . And possibly plywood over that, probably something thin and easy.

Finally I assume whatever I do to leave the ridge vent open of course when I do the roof, and should I take it all the way to the ground or leave it off a foot or so? Thank you. I am new to all of this and I am under some serious time constraints.

https://www.menards.com/main/paint/...ier/p-1444426340427-c-8188.htm?freeFormRowId=

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[Jess]

Tyvek is an air and moisture barrier, not a vapour barrier, so would be ok immediately under the sheeting. Depending on your location, a poly or similar vapour barrier may be required on the warm (usually inside) of the building to protect the insulation from moisture condensing in it. In my colder climate, we do Tyvek on the outside and 6 mil poly on the inside of the insulation.

 

[nadogail]

I may be mistaken, but this product looks to me as if it is a private label equivalent to Tyvek.

 

[Mr.wolf]

So no worries about this or the tyvek being directly on the steel? Also on the inside does the poly go between the tresses/posts? That way the insulation still fits between them? Thank you guys very much I need to do this Friday. This building already went over budget (don't they all) so if the linked product will work in place of tyvek it will save some money.

My concern is having something between the steel and the eventual insulation so the condensation does not soak the insulation. Am I thinking correctly? Or do I just do the insulation and then the vapor barrier?

 

[csp]

Water vapor will pass through housewrap, liquid water will not. Condensation starts out as water vapor.

I wouldn't use it directly under the steel if it were mine for that reason.

 

[Mr.wolf]

Ok. So maybe I should just wrap the whole thing (directly on purlins and girts) with felt underpayment (tar paper?) I'm sorry to be a pain there just seem to be so many opinions on this. I've been reading the inter webs all night!

Eta: so after tons of reading it seems synthetic roof underpayment on the purlins and girts and metal roofing directly on that?. So the next question would be, on the walls can the rolled insulation go up directly against the synthetic underpayment or will to much water transfer into the insulation?