[Mbcker]

Hey all,



First time on the forum asking questions as I tackle my latest house project. I have a 1940's detached garage in Seattle which I intend to use for band practice once I finish cleaning it up. My plan was to tear out the inside 1/4" "walls", insulate the 2x4 framing with fiberglass bats, insulate against the roof, and then cover all the insulation with plywood. I bought all the materials and just started tearing out the inside "Walls" and discovered that the outside slats are attached directly to the 2x4 studs with only a backing of 1940's kraft paper that's in bad condition.



I realized at this point, I probably can't fill these spaces with fiberglass bats due to possible moisture contamination over time.. so I'm trying to figure out what to do at this point. Easy and cheap are the priorities But I'm also interested in soundproofing as much as possible due to the band practice. What I came up with is either:


1) Pull off all the slats and install rigid foam insulation 1/2" board and then reinstall slats, seal from the inside with great stuff. Then continue as planned with fiberglass & plywood on the inside.
2) Pull off all the slats and install 1/4" plywood sheathing, reinstall slats, continue.
3)Return fiberglass and use Rockwool insulation instead at slightly higher cost (I think I can use this w/out sheathing w/out any harm?).
4) Buy 1/2" rigid foam insulation and cut to framing spacing and install on the inside, seal with greatstuff, and then install the fiberglass bats over it. (This would slightly compress the fiberglass since it's 3 1/2" thick going on top of the 1/2" foam board. This is also the easier option as I see it since I don't have to pull of any siding. Is this a bad idea? Should I go with another option, or is there an option I'm not thinking of?



thanks!

 

[Guap0_]

You are right about not using fiberglass bats because it might trap moisture but what's the ultimate goal? Do you want to build a recording studio? Why the soundproofing?

 

[Mbcker]

Just a garage jam band, but I am trying to limit the annoyance of neighbors and my wife by keeping the sound down.



I suppose the easiest thing to do is return the fiber insulation and go with rockwool -- but I like the idea of sealing off the insulation space from the outside still. Can rockwool be exposed to the outside? Ultimately I think it's around $250 to get 1/2" rigid insulation and install between the framing before the fiber insulation.. def. prefer this route unless it's a terrible idea to try to stuff this plus the 3 1/2" fiber insulation in the space.

 

[Guap0_]

True soundproofing is very expensive. One of the cheaper ways, so I'm told, is to use cork. Take it w/ a grain of salt.

 

[Mbcker]

I will look into that, hadn't heard of it before. Soundproofing is a secondary goal I would say to the primary goal of protecting the insulation and sealing the building though. I don't have a ton of $$ to spend on soundproofing so whatever benefit I can get there with the materials I'm using to insulate and seal the garage is sort of bonus.

 

[Guap0_]

How far away are the neighbors?

 

[Mbcker]

They are right next door - their yard is directly adjacent. House is probably 15' away.

 

[Guap0_]

Ask him to join the band.
Edit: I shouldn't make a joke out of it. That's quite close. As you said, you don't want to spend a lot of money so use whatever you have & look into sheets of cork.

 

[Mbcker]

Ask him to join the band.
Edit: I shouldn't make a joke out of it. That's quite close. As you said, you don't want to spend a lot of money so use whatever you have & look into sheets of cork.

haha yeah that would be ideal, right?!



My boss suggested Tyvek strips done on the inside of the bldg, stapled to the studs and against the outside slats. I am considering that now.. although somehow rigid foam seems easier to deal with and would provide slightly more sound barrier and be easier to completely seal using foam around the edges.

 

[Guap0_]

I never thought of Tyvek. Is there any way that the foam & the Tyvek can both be used?

 

[Mbcker]

I never thought of Tyvek. Is there any way that the foam & the Tyvek can both be used?

YEah, that was the conclusion I came to after talking to a few more people. I ripped out all the old kraft paper, and am bending any stray nails out of the way from the siding. Then will cut oversize strips of tyvek and staple into each space between studs. Will cut 1/2" foam then and fit over than, possibly caulk a bit against the tyvek. Seal the edges of the foam against the studs with greatfoam. Then finally insulate with 3 1/2" R13 fiberglass bats. A little research turned up that compressing a bat by 1/2" (to accommodate the foam) will only decrease R-value by maybe 2 while adding the foam increases it by 4 - 6 so it's a net gain and I get more moisture protection. Win win.