What Should be under vinyl siding?

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Joined: Mon May 30, 2011 8:32 pm

Mon May 30, 2011 9:00 pm


Bought an older doublewide, 1989 if I remember correctly. Anyways, I was doing something with the siding, and noticed there was nothing behind the siding. Just studs and insulation. Shouldnt there be plywood or OSB or foam boards or something??


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Mon May 30, 2011 11:35 pm

My 1987 has foam board, but I seem to remember that was optional at the time I ordered the home.

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Mon May 30, 2011 11:50 pm

Vinyl siding can be installed over sheathing, foam board or the old siding using 1x4 nail strips. What must be immediately under the siding is a moisture barrier, like Home Wrap. Fan-fold foam or foam panels can work as moisture barrier if properly taped when installed. I have a hard time believing the tape stays, but that is how they do it.
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Tue May 31, 2011 9:50 am

Yea, i pulled off a section and it was just studs and insulation.

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Tue May 31, 2011 3:29 pm

JD, do you know if the HUD code calls for moisture barrier? I installed a new (real) door on the side of our house over the long weekend, and my helper and I both noticed that there is nothing between the siding and the sheathing. We wrapped the opening with membrane flashing, but all we had to stick it to was the raw OSB and 2x framing.

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Tue May 31, 2011 4:36 pm

Well as you have found what SHOULD be there and what is usually two different things. You may want to think about adding sheathing if you are planning on staying there.

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Tue May 31, 2011 8:55 pm

How easy/difficult would it be to remove the siding and then put it back? I guess I would have to number each piece so it would all go back together nicely.

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Tue May 31, 2011 10:17 pm

If you are going to remove the siding to put something like 7/16th OSB sheathing and then Tyvek on just do it in sections and you should be OK. Just lay out the siding on the ground the same way it was on the house. Start removal from the top. One thing that you might run into is around the windows if you run the sheathing around them they would be recessed a little and you would have to wrap it maybe with aluminum to seal it up. Or possibly you could take out the windows as you are putting up the sheathing. If they are the kind with all the screws around them they could just be put back on the top of the tyvek covered sheathing and then you could just fix the trim in the inside.