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Bathroom Renovation-Insulation Questions

I am gutting my 8x8 bathroom for renovation. There is currently no water damage, with regular sheetrock, and kraft faced insulation in the exterior and ceiling (unheated attic space above). There are no major problems with the insulation or sheetrock save for a lack of interior insulation which means when you make any noise everybody in the house hears it. The renovation is for asthetic and multiple minor reasons (cracked drywall, acrylic tub finish worn, vanity in poor shape, odd & noisy bath fan needs replacing, etc). It was just better to start over. My questions.....

1. I would prefer to use the plastic encapsulated insulation by Owens Corning or Johns Manville, but nobody carries it or can get it in central NY. I prefer it as it does not irritate as much during installation. Does anyone have any suggestions on a source?

2. Barring this, I can use kraft faced insulation or unfaced with separate vapor barrier. I will probably use kraft faced because it held up well before (but was horribly installed) and is more readily available in this area (unlike the plastic encapsulated stuff). Does anyone have any preference as for the placing of the kraft vapor retarder (inside the studs or overlapping on the face of the studs)?

3. For the interior walls, since both sides are heated, does it matter if the insulation has vapor retarder or not?

Thanks for the input!!


Re: Bathroom Renovation-Insulation Questions

I can't help you with question 1

For question 2, a separate barrier would be better, but if you do use kraft faced, staple the flaps over the ends of the studs, not the sides as usually done.

Question 3, If you insulate an interior wall, you should have the barrier facing the "wet" room. You want to keep the moisture out of the insulation.

If you are insulating between rooms, I assume its for sound proofing, I can't see any other reason. For soundproofing, you might want to consider rock wool instead, it's better for sound insulation. Stapling the flaps on the end of the studs will also help reduce sound transmission but there are some products made specifically for this purpose you might want to look into.

Re: Bathroom Renovation-Insulation Questions

3. For the interior walls, since both sides are heated, does it matter if the insulation has vapor retarder or not?

It's completely acceptable and not required to apply a vapour barrier or retarder to insulation within interior wall cavities.
The vapour should be free to pass through the interior walls for drying.

Re: Bathroom Renovation-Insulation Questions

just as canuk says, if you have the coin go with spray foam. you will get a much higher r-value and you can go with porous foam for the interior walls and get more mass in the cavity to help with sound

Re: Bathroom Renovation-Insulation Questions

Yes! Right! Foam is that magic stuff that can fix anything!!! :)

Re: Bathroom Renovation-Insulation Questions

1. Foam is distinctly better for thermal isolation, quite bad for acoustic isolation.

2. Mineral fiber is not better than fiberglass for in-wall damping of resonance.

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