Home insulation & vapor barrier

[cmartin]

Adding on the house and like roxul, good for sound absorption, doesnt rot or burn, good r value... Only issue I see is the lack of a vapor barrier. After lots of reading vapor barrier seems like Ford vs Chebby, every opinion from dont use it to use the old school poly sheet method.

It sounds like a vapor retarder is the preferred thinking at this point. Does anyone have experience with certainteed membrain (http://www.certainteed.com/products/insulation/mold-prevention/317391) ? Seems sort of like gortex for the wall and makes sense on paper.

If not this any other recommendations when using Roxul in a wall insulation application?

For ease of application blowing cellulose into the attic seems to be the best option, any reason to deviate from this?

[Cliff Claven]

from what i know of certainteed they make some good products. and if that one does what it says it would be nice.

[William Miller]

Vapor barrier on the inside or outside?
If outside, My last project we used zip system with insulated boards. Very quick and easy to tape the seams.

Monkey county now required R19. Thus R13 in 2x4 walls with Zip foam panel on outside.

Next question, if vapor barrier on the inside, are you going to glue the drywall?
A lot of guys do this but dont staple the paper face on the edge of the 2x4. Thus its not really a good seal.

You may have to ask code review or an inspector what is the best way to do both. They see a lot of work and everyone has their own way and reasons for doing it that way.

Good luck. Keep us posted!

[cmartin]

Thanks Bill, good info.

At this point I'm looking for an interior vapor retarder. Roxul is unfaced and there are several opinions about proper installation in this area. Current thinking seems to be dont use poly and if you install a vapor retarder it should be a high tech material, but old fashioned kraft paper works too.

I think you are right, whatever the inspector wants is right. Similar insulation requirements here and 2x6 walls is simple solution for most walls. I havent seen the final plans yet so I'm curious how this will be addressed in the walls that are staying. There are a few interesting options is using 2x4 walls, EXP on the exterior, spray foam in the walls.... really interesting stuff.

[cmartin]

New option seems to wet/damp blown cellulose. Cheaper than roxul, good air barrier and good/decent sound deadener. Anything to worry about with blowing cellulose into a wall?

One primary concern is sound reduction from the attached garage and laundry room. Quietrock seems like a decent product with some good #'s to back it up, anyone using this? Paying ~$50/sheet for drywall seems nuts but big picture it isnt that much coin and if the stuff works like it says it might make sense.

[BlackTalon]

This is manufacturer-specific, but should till give you a good idea of sound transmission class (STC) ratings for different configurations. http://www.usg.com/content/dam/USG_Marketing_Communications/united_states/product_promotional_materials/finished_assets/acoustical-assemblies-en-SA200.pdf

You installing a second stud wall in the garage that is independent of the current exterior house wall? Usually a double-stud system w/ various different gyp boards, insulation, etc. can get you where you are looking to go.

[cmartin]

Thanks, good info.

The current idea is to just use 1 wall, insulted and maybe double drywall or the fancy sound reducing drywall. If noise is a problem, adding something to the garage side of the wall should be straight forward.

I'm not looking for 100% quiet but dont want the family room to sound like a Mr Tire waiting room either.

[BlackTalon]

I lived in a condo for ~6 years that used wood studs and drywall for all walls and ceilings. I think it was before they started really using the double stud system; and instead went with double layers of gyp board and an 'acoustic' insulation. Anywho, there was no question about when the neighbor's van was a-rockin'...

[cmartin]

Good stuff. Reminds me of staying at the Town House in Charlestown a few times.. never again.

[Dr K]

New option seems to wet/damp blown cellulose. Cheaper than roxul, good air barrier and good/decent sound deadener. Anything to worry about with blowing cellulose into a wall?

One primary concern is sound reduction from the attached garage and laundry room. Quietrock seems like a decent product with some good #'s to back it up, anyone using this? Paying ~$50/sheet for drywall seems nuts but big picture it isnt that much coin and if the stuff works like it says it might make sense.

We have Quietrock on the ceiling of our man-cave. It does a very good job of quieting the sound, but we have an uninsulated door at the top of the steps up to the main part of the house that lets up quite a bit of sound. But sitting in the living room just above the man cave it's quiet!. Yes, the stuff is expensive.

[cmartin]

Thanks, good info.