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Bathroom insulation and vapor barrier?


antnida
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We just bought this house that was build in the 60's, pretty much rip it down to the studs since there was no insulation in the wall and a lot of items that needed to be updated. We will start with the bathroom remodeling first. I'll be installing non faced insulation in all the wall of the bathroom followed by a vapor barrier, the bathroom wall is going to be 3 pieces of cultural marble (Marblestone). I'll be using durock or similar product (doesn't look like home depot or lowes carry durock) for area where the shower walls and 5/8" green sheetrock for everywhere else

My question is do I insulate all the wall down the wall around the tub or just to the lip of the tub only? As for the ceiling, do I install faced or non faced insulation? One more question that does not related to insulation, is the bathroom's sub floor, right now it's 2x6, should I add a layer of plywood before putting down a layer of cement board for tile on the floor area?

Thanks

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My question is do I insulate all the wall down the wall around the tub or just to the lip of the tub only?

All the way down the wall. Otherwise your insulation envelope will have a big hole in it behind the tub.

As for the ceiling, do I install faced or non faced insulation?

Faced. 'Faced' means that it has a vapor barrier on it, which you should have to retard the flow of moisture from the bathroom interior to the attic space.

One more question that does not related to insulation, is the bathroom's sub floor, right now it's 2x6, should I add a layer of plywood before putting down a layer of cement board for tile on the floor area?

I see no reason for that. You do understand the difference between 'floor joist' and 'subfloor' do you? 2X6 is a common size of lumber for joists but I've never seen it installed as subfloor. Subfloor is usually 1X planks or 3/4 plywood.

Marc

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I'll be dang.

How do you figure deflection where the joists are 2X members laid broadside?

Marc

Well, you could use IRC Table 503.1, but around here we pretty much just put it on girders spaced 4'0" on center and it's fine. You're supposed to use T&G material but it usually shrinks so much that the tongues don't end up sitting in the grooves very well anyway. I regularly see square-edged stock in 2x6, 2x8, & 2x10 sizes.

Makes for a nice solid floor.

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Oh. . . the original poster's questions . . .

Insulation all the way to the floor.

If you don't want to investigate if your floor is stiff enough, add a layer of 5/8" or 3/4" plywood, then cement backer. Make sure you'll be ok with the lip on the floor created by the added plywood though.

Vapor retarder/barrier. . . ? That's a bit more tricky. . . go to buildingscience.com. I'm sure they've got a good wall detail for your climate.

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. . . Jim mentioned girders on 4' centers. I often seem them on 5' or 6' centers. . .

Most of what I see is hemlock and it's only supposed to span 4'. You're allowed to go up to 5' if you use fir. It's never supposed to exceed a 5' span. Of course, I see it done occasionally out in the sticks and across the river in . . . ahem . . . Washington State.

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Insulation on the exterior wall and ceiling needs a vapor barrier. As for what kind and where to place it, I have no idea what is customary in Cali. Insulation on interior walls is for sound control and should not have a vapor barrier at all.

I think I'd want to incorporate some kind of isolation membrane into that tile floor regardless of whether you add plywood or not. Think Kerdi or Schluter.

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. . . Jim mentioned girders on 4' centers. I often seem them on 5' or 6' centers. . .

Most of what I see is hemlock and it's only supposed to span 4'. You're allowed to go up to 5' if you use fir. It's never supposed to exceed a 5' span. Of course, I see it done occasionally out in the sticks and across the river in . . . ahem . . . Washington State.

Yep,

We'uns is uncivvylyzed up he'ah.

Wun Teem - Wun Fyt!!!

Mike

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We will start with the bathroom remodeling first. I'll be installing non faced insulation in all the wall of the bathroom followed by a vapor barrier,

Just curious, but why are you going to use unfaced insulation and then add a vapor barrier? Why not just faced insulation? And what kind of vapor barrier to you plan to use?

A couple of weeks ago someone had a very similar issue and I recommended using closed cell spray foam at the exterior walls of the bathroom. Sacramento might be too mild of a climate to make this worthwhile, though. Check out the July 2011 issue of the Journal of Light Construction and look for an article titled "Energy Retrofit in Stages."

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Thanks you everyone for helping out, with today economic state we just afford to hire a contractor for this remodeling task being handy around the house I just have to do a lots of reading, ask questions and do my best :)

I haven't got a chance to go down to the sub floor to measure how far apart are the griders as of yet, too bz tearing down all the sheet rock, no insulation on any of the walls there are very fine one on the ceiling though.

I understand the differences between floor joists and subfloors, just haven't seen one that did it with 2x6 vs plywood. Talking about plywood, there aren't any on the exterior wall either, doesn't looks like it required in the 60's.

Going back to the insulation and vapor barrier for the bathroom, if I were to use unfaced insulation with vapor barrier then the material for the vapor barrier would be Certainteed MemBrain.

Looks like at this point I will be installing faced insulation for all exterior walls and unfaced for interior walls. As for the bathroom floor, I'll just install cement board and tile over it. I'll post some pictures once insulation is completed.

Thanks

Tony

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. . . As for the bathroom floor, I'll just install cement board and tile over it. I'll post some pictures once insulation is completed.

If you do that, re-secure every piece of 2x6 with two screws at every girder. Then install your backer board in a layer of thinset that you apply with a 1/4x1/4 notched trowel. Screw it down every 6" in both directions with the proper screws.

If you find that the girders are more than 4' apart, I'd add a layer of plywood.

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