vapour barrier

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vapour barrier

Postby iam_turner » Sat Jun 30, 2007 1:11 pm

Hello,

I am new to this site, and new to mh ownership - currently I feel like I have bitten off more than I can chew. My wife and I (newly weds) noticed a smell of mold in our bathroom and laundry room. As I am fairly handy and have worked with my hands for a number of years, I figured I could redo the bathroom and laundry room without too many issues...Well, I am thinking I was wrong.

Anyway, I have since gutted the laundry room, removed two layers of SOAKING plywood (black with moisture and mold) and the particleboard flooring (which was in good shape, somehow it avoided the wrath of the moisture). The moisture appears to have been coming from the bath tub, and p-trap from the washer which was not correctly installed. Anyway, I removed all the flooring down to the joists. Then the real smell began to come to light, and the insulation which was under the floor was damp and stunk like old pee. I removed that, and then noticed that the underbelly is moldy. I really do not know what to do.

I was thinking of just ignoring the underbelly, replacing the unsulation and rotten wood, vapor barriering the floor on top of the new insulation and laying new PWF plywood with a new subfloor. But then I was reading on here and it looks like the vapor barrier goes between the insulation and the ground, is there anyone out there that can provide some advice/assistance?
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RE: vapour barrier

Postby Yanita » Sat Jun 30, 2007 1:35 pm

Hi, Welcome to the site!

Do not get discouraged so soon. Although these repairs are labor intensive you can get it done, and LOL, you have come to the right place for assistance.

Ok, we will start at the beginning, 2 layers of wet plywood and 1 layer of particle board, so in essence you are saying that there is/was 3 layers of flooring.

The sub floor is one layer. First your have floor joist, which is covered with OSB, particle board or plywood, but no more than one layer. That is your sub floor, you are not suppose to have multiple layers. Since you do, I have to assume that someones fix was to lay all this other wood on top and failed to fix the plumbing leak!

OK, you have removed everything..let your floor joist dry out. If need be put a fan in the area and get the air really moving. Remove some skirting if able to and get even more air under there.

If the joist are showing signs of rot, you should replace them, or at the very least sister them with 2x6's.

Remove all damaged insulation.

Underbelly is moldy? Are you meaning that the belly material has mold on it? If so, spray with a bleach solution, and make sure this area dries real well.

A vapor barrier is a sheet of plastic at least 6 mils thick, that goes from end to end side to side of your home. Overlay all edges by at least 6 inches and seal with tuck tape. Bring all the edged tight to the skirting and the piers that your home sits on. The plastic barrier keeps evaporating ground moisture from penetrating the bottom of your home. Some folks do not use this but in some areas such as mine it is code. Check with your codes office to see if it is mandated. If your home is naturally damp underneath I would put it done if nothing more than for preventive maintenance.

Now, when you replace your flooring remember that you only need one layer of wood, preferably plywood and then cover with full vinyl in the bathroom/laundry area is the most recommended way.

I will leave you with a link that shows you how mobile homes are constructed.

Since you are good with your hands and sounds like you will be doing your own repairs then I highly suggest you purchase The Mobile Home Repair and Upgrade Manuel from this site. It can be located in the BOOKS/PARTS link above. This Manuel has great pics and easy to follow instructions.

If we can help further please keep asking your questions.

Have a great day...

Oh yeah, Congratulations on your marriage!

~Yanita~

oops here's your link http://www.mygreathome.com/fix-it_guide/diagram.htm
Last edited by Yanita on Sat Jun 30, 2007 1:55 pm, edited 3 times in total.
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RE: vapour barrier

Postby troyster » Sat Jun 30, 2007 1:38 pm

seeing that your from Canada and not the southern states If your going to install a vapor barrier it must go at the top of the floor joists above the insulation ( warm side ) and if you don't remove all the mold in your floors whether it be plywood/ particle board floor or floor joists it will continue to grow and spread as any microorganism will. do your self a favor and buy Mark's book it will show you how to do any major repair on a mobile home.
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RE: vapour barrier

Postby iam_turner » Sat Jun 30, 2007 2:05 pm

Awesome!
Thanks so much for the replies, I have a couple more questions, related to this fix.

As I don't have the time/money to replace all the underbelly, which will most likely need to occur because of the extensive damage of the mold - can I replace sections at a time? Here's what I was thinking...

Replacing the chunks of moldy underbelly and insulation under the bathroom and laundry room (approximate area of 9x11 square feet) by cutting out the old underbelly material and replacing with 6mm poly, but as isolated as possible from the other insulation/underbelly so as to prevent further mold spreading to the nice new materials I put in now?

I know poly will not be as strong as the underbelly (mine appears to be constructed out of quorter inch board material), but i've read on here the people have used tyvek and to my thinking poly would not be much different?

would this be a suitable fix? So long as I continue when time/finances permit to replace the entire underbelly?
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RE: vapour barrier

Postby Yanita » Sat Jun 30, 2007 4:09 pm

Hi,

Tyvek is better, it is breathable...regardless if you are from Canada or the southern states in the US.

The type of underbelly you have is called buffalo board, although there are other names for it as well.

Good luck in your repairs.

Yanita
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RE: vapour barrier

Postby troyster » Sat Jun 30, 2007 4:23 pm

Iam you cannot use the 6 mil poly at the bottom of the insulation as this will trap moisture in your joists and insulation. you have to use a "breathable" material to hold up the insulation, the poly has to be above the insulation on the top of the joists and under the plywood floor. sorry if there was confusion. For the bottom of the floor joists you can use Tyvek or breathable foam board, tar paper or the impregnated belly material that Mark sells on his site. Good Luck!
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RE: vapour barrier

Postby Greg » Sat Jun 30, 2007 6:31 pm

Very good advice from Yanita & troy, they both know what they are talking about. One other thing to look very close at is the tub itself, plastic tubs are known to crack, usually around the drain so what looks like a trap leak could be a crack in the tub. Greg
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RE: vapour barrier

Postby Yanita » Sat Jun 30, 2007 8:25 pm

HI,

Just for clarification I am referring to a moisture barrier that is placed on the ground.

Around here, most mobiles are not built with a vapor barrier in the floor system. The underbelly is expected to keep ground moisture during evaporation from wicking up into the under belly.

Many folks here in the states put 6 mil plastic on the ground as described in my first post. Some states this is required by law, but may not be applicable in your area. Regardless, it is a great preventive measure for your home should you live in an area that has damp ground.

As for replacing your underbelly in sections...just remember that the longer your belly is open the more subject it is to critters and bugs. Be certain that all areas are completely dry and have been sprayed with a bleach solution prior to repairs. If anything is left damp your mold/mildew issues will resume.

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RE: vapour barrier

Postby iam_turner » Sat Jun 30, 2007 8:39 pm

Alrighty,

Thanks for the clarification and further responses, I will scratch the idea of using polly instead of the underbelly - I'll look around town for buffalo board, or tyvek. - I live in the FAR far North (above the 60'th parallel and we don't have too many problems with critters under our trailers - mine is skirtted well, and the rodents don't bother with my mh too much.

WE also have sand as our base soil, so moisture shouldn't be too much of an issue under the trailer either, but I'm going to do what was suggested and place the 6mm polly on the ground before winter. HOpefully this will help with the dampness.

Cheers!
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RE: vapour barrier

Postby Yanita » Sat Jun 30, 2007 8:42 pm

Good luck with your repairs and keep us posted on the upgrades to your bathroom.

If you need further help please post again. :lol:

~Yanita~
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RE: vapour barrier

Postby JD » Sat Jun 30, 2007 9:34 pm

I would recommend you use mobilehome underbelly, a product you can get here at mobilehomerepair.com.
http://mobilehomerepair.com/Order2.html#catalog

We keep a couple of 14x70 pieces in stock and use it all the time. We use the Sta-Put spray adhesive or a heavy duty 3M product and staples. This is the material made to be use for underbelly. It is also very cheap. Mark will ship you out the size you need. I have bought materials from Mark a couple of times and it has always been excellent service.

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All information and advice given is for entertainment and informational purposes only. The person doing the work is solely responsible to insure that their work complies with their local building code and OSHA safety regulations.
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RE: vapour barrier

Postby Maureen » Sat Jun 30, 2007 11:22 pm

I have to agree with JD on this one!

Poly as a ground vapor barrier is just fine, maybe in even Tyveck. We don't have a problem here with moisture from the ground at all.

Vapor barriers and belly materials are two different things.

If you're replacing the old buffalo board, it's no longer available.

You want to replace it as JD described in his post.

Maureen 8)
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