vapor barrier under wood flooring

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Old 12-14-02, 11:02 PM
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Question vapor barrier under wood flooring

I pulled up linoleum tiles(?) and the slab immediately released moisture but dried in minutes. I've read about using 6mil barrier, then building paper, then 3/4 plywood, finally 3/4 hardwood flooring. (if that order is wrong please let me know). I plan on using a powder actuated gun to adhere floor plates and plywood. Does punching so many hole in the moisture barrier cause a problem? should I be looking into "floating" wood flooring instead?
 
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Old 12-15-02, 06:52 AM
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stephen001,

It is not recommended to place solid hardwood flooring in a baement. Moisture will raise havoc with it and be destroyed within a short period of time. Your options would be a laminated type flooring (floating floor) over your plywood. The cost would be cheaper than solid and since it is glued to each other, it will be impervious to any dampness.

The issue of a vapor barrier such as plastic isn't a bad idea but it is suggested that a vapor barrier that has dimples be used. This allows for air flow so that any moisture can dry out that would be underneath.

An alternative product is the link below for a subfloor:;

http://www.subflor.com/floating-sys.html

I would recommend a dehumidifier be used at all times regardless of the type of flooring used to minimize potential problems.

Hope this helps!
 
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Old 12-15-02, 08:43 AM
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No 3/4" solid hardwood flooring manufacturer warrants their product for installation below grade. Furthermore, 3/4" plywood over concrete is not a sufficient nailing surface for most manufacturers if you plan to nail or staple. I suggest that you investigate the higher quality engineered hardwoods -- ones with a 1/4" hardwood layer (not the fake "laminate" flooring such as Pergo). Not only are these approved for installation below grade, but you can skip the plywood if you want (install it floating over the vapor barrier). The results will be indistinguishable from solid hardwood. It may only last 100 years instead of 200, but do you care?

P.S. It might have been better to leave the linoleum there underneath the wood floor. It's a decent moisture barrier, and provides some cushioning and insulation.
 
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Old 12-16-02, 10:50 PM
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Thanks thus far. Could not leave the linoleum tiles on the floor - The redish brown tiles popped off the floor whole when I pulled up the old carpet underlayment, the tan ones might as well be part of the slab (anyone what to tell me how/why that happened?)
More Importantly -
1. If I lay down a "moisture" barrier over the slab how do I seal the seams?
2. I read that it should extend up the wall after passing under the PT floorplate. Does it just hang loose? get adhered to the wall? or what?
3. An issue concerning mold being created under the "moisture" barrier on the slab is mentioned often. Is this going to happen? should it concern me?
4. If I don't use a moisture barrier across the entire slab because I may change flooring methods between rooms how do I stop any moisture from especially creeping out at that junction? Gluing the barrier to the floor?
 
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Old 12-17-02, 04:26 AM
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stephen001,

If you looked at the sites that I gave you and use bubble (dimple) vapor barrier, the air flow underneath this will allow for a drying process.

Since you know that you had moisture under your tiles, this is common when any material is just laying against a cold service. It doesn't happen when air is allowed to breath under or through it. Mold and mildew can be problems but the issue is constant moisture, poor air circulation is what enhances the growth of these problems. The link showed the product that would be the best to accommodate both carpeting and other floor types. Alternative is to use 1x w/t stock, 16" O.C., then place vapor barrier 6 mil (not glued) over this and then 3/4" T & G plywood. This does not mean you should put hardwood flooring down in the basement. Engineered or laminate products only or ceramic tile/carpeting only. You then can do whatever you want then. This application may rob 2" maximum in your lower level height but this is cheaper than buying a prefabricated product as the link describes. Also your flooring transistions can easily be joined with no problem. And no, the vapor barrier doesn't have to glued to a wall or anything, let it lay flat. You walls on the perimeter can be placed directly on the concrete if you use W/T plates. Some apply the wall over the 1x and subfloor which is applicable as well.

Bear in mind, condensation is only a problem when it cannot dry, air releaves this concern.

Hope this helps!
 
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Old 12-17-02, 11:54 AM
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thanks yet again. i called regarding the dimpled product
"subflor". the building supplier doesn't stock it. said it's only been asked for twice. he thought it ran about $1.10 or more per sq ft. i will go for the engineered flooring and investigate the subflor product a little more.
question - do i then use a barrier of any sort on top that? building paper? or do i just place the floating floor pad directly on top? or glue down the engineered flooring?
 
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Old 12-17-02, 12:34 PM
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stephen001,

You will get instructions with your order but I have attached a link for your review;

http://www.directwood.com/engineer_instruct.html

Hope this all helps!
 
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Old 12-17-02, 12:42 PM
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stephen001,

Here is a better link with more specifics and how to's;

http://www.thisoldhouse.com/toh/home...6032-1,00.html

Good Luck!
 
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Old 12-17-02, 05:29 PM
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All flooring manufacturers will have their own specific instructions. As a moisture barrier, 15# roofing felt taped at the seams with duct tape is typical. But engineered hardwood manufacturers often recommend a vapor barrier that also provides some cushion. Normally you do not try to put the vapor barrier under the sole plate, but you do wrap it a couple inches up the wall, which is concealed by the baseboard.

The link Doug provided is an excellent overview. The last page of his second link covers installation over concrete. Expect much more detailed instructions from the manfacturer. Always follow exactly the manufacturer's instructions -- they differ with each one. You will normally have several installation options (nail, staple, glue-down, float).

I've found that all that standing up and kneeling down is exhausting. It might be better to have a helper so that one of you can stay on your feet and the other stay on your knees. In any event, don't plan on a night of dancing afterwards.
 
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