Need barrior when using insul-siding?
whardy7
| Posted in Energy, Heating & Insulation on
Should I use a vapor barrier if I am going to use the insulated vinyl siding? I have read both opinions. I have a 2×6 wall filled with batts, and osb sheathing.
Thanks for any advice,
Wayne
Replies
Greetings whardy7,
This post, in response to your question, will bump the thread through the 'recent discussion' listing again.
Perhaps it will catch someones attention that can help you with advice.
Cheers
40,000 Americans are injured by toilets each year.
Like rez, I'll bump your thread back up.
I'll also give you MHO.
By vapor barrier, do you mean house wrap or felt paper over the osb? If that is the case the answer is yes. By all means use something under vinyl siding.
We have had this discussion before, so let me point out that the 2002 IRC does not require it, and someone will be sure to point that out. However, good building practice is to use either a house wrap or felt paper under vinyl siding because no mater what the manufacture claims, it will let driven rain get behind it. In fact with some poor flashing details a light rain will do the same. The house wrap or felt is your primary defense against soaking your sheathing and rotting your wall system.
Dave
I do not know if it makes any difference or not, but this siding is all under a 10' wrap-around porch on all four sides.
I wasn't sure if it made a difference that there is a special Dow foam attached to the backside of the siding. Would it sweat more with the foam hugging the house wrap?
Thanks for the help.
Sweating where?
I have not used the product you have described, but have installed vinyl with drop in or fan fold insulation behind it. Neither of those two insulation will make a vinyl siding install water tight. I don't think I have ever done a vinyl job that I would consider weather proof. Good flashing details and house wrap or felt behind the siding has always prevented any water from getting into or on the wall sheathing. The siding will turn away nearly 100% of the weather from impinging on the wall. It si the small % that gets behind it and soaks into exposed sheathing that eventually causes rot.
If you mean sweating on the back side of the siding, I would definitely want a barrier between the condensed water and the sheathing. If it is on the surface of the siding, it is called dew, and you ain't gonna ever stop it.
As far as being under a 10' wide porch. It wouldn't make any difference to me. I would still use house wrap or felt under the siding. I've seen it rain sideways in a good storm.
Dave