vapor barrier under flooring

[mccrackin]

I was about to replace the skirting around a mobile home I just purchased, and noticed that under the addition that has been added at the entrance they have vapor barrier underneath the insulation. That is, it's attached between the ground and the insulation. Isn't this supposed to be ABOVE the insulation, just underneath the flooring? If necessary, my thought was to rip the plastic down and leave it sitting on the ground under the insulation, and then use 3/8" OSB (I have lots on hand) under the insulation to seal things up. Are there any problems with this plan?

[hhb]

Sounds like a good plan to me. Probably done in an attempt to mitigate drafts. I think sometimes people go crazy trying to seal up everything with plastic, spray foam and so on, only to find out later it was a bad idea when everything goes mouldy because they didn't allow things to breathe.

[Greg]

Hi & welcome. The barrier DOES indeed go between the insulation and the ground. The "Barrier" is there to support the insulation, you need air space between the insulation and floor. The air space allows warm air from the heat ducts under the floor to keep the pipes from freezing.

The original underbelly material will allow water to drain out in the event of a plumbing leak so do not use plastic. House wrap should work. You need it to breathe.

6Mil. Plastic on the ground is great as a moisture barrier to keep ground moisture out from under the home.

Greg

[1987Commodore]

I don't think the osb is a good idea in this case. I would make sure the barrier used can breathe a little to avoid mold, particularly if the addition is heated.

[JD]

This is the stuff to use for your underbelly. It is the right stuff and it is pretty cheap as materials go.

http://www.mobilehomerepair.com/underbelly.htm

[hhb]

I stand corrected, but then again I'm a newbie at this mobile/mini home thing. OSB is probably not the thing to use, what JD has in the link above is a much better idea.

[mccrackin]

Thanks for all the replys. Is the underbelly material something that can be pickup up at home depot or the like? I would like to order it online, but I live in Canada so the shipping kind of makes it not worth it.

[Greg]

You should be able to find the original type material at a Mobile home supplier in your area. Most home centers around here don't carry it. There are people that do use Tyvek, I guess it may be the best option if you can't find the original type.

Greg