Hey, I read on the greengluecompany.com site that one way to help eliminate the sound going through the floor was to put a couple layers of sheetrock with green glue in between and screw them into the subfloor above the theater. Has anyone tried this with success?

I have a bunch of sound board left over and was thinking of just cutting it into strips and filling in the areas against the subfloor between the joists... Probably try and avoid green glue to help save a few hundred dollars...

bummmmp.

Do a search on green glue and you will find a ton of info, there was agreat thread where bpape did a great job of explaining pros and cons of each different method.

I am no expert, so wait for someone else to weigh in, but from my reading, think de-coupling the ceiling from the floor joist will be their first recommendation.

If you were to hit the floor joist with your fist, you would hear it above whether you have soundboard in between or not.

It would be a great first hand test for you to put up 5/8 drywall on the ceiling, then test with some speaker setup... if it is not satisfactory, then spend the $$ and add the next layer of green glue and drywall.

The other option would be to decouple the ceiling, and go that route... but I think GG would be cheaper...

My 2 cents.

One inexpensive (but less effective) way to de-couple the ceiling is to use furring strips perpendicular to the floor joist, then double drywall with GG between layers. There should be adequate insulation above the double drywall as well. This worked well in my situation, and it is hard to tell that a movie is playing when listening in the room above the theater.

Ken

Soundboard alone will not really do much for a couple of reasons.

1 - All you would be doing is adding Mass to the floor/ceiling assembly, and what you need to do is stop the resonance and conduction of the noise traveling through the system by damping, and/or decoupling.

2 - As you know, Soundboard is very light at 38 lbs/4x8 sheet (1.2 lbs sq.ft.) so therefor does not add any noticeable Mass to the system. (You would be better off doing your idea with inexpensive 5/8" drywall @ 2.2 lbs sq.ft.

Ken's explained system is more on the mark with decoupling and damping being used. The use of clips and hat channel would perform better.

You can incorporate your idea if you tweek it a bit. Take your drywall scraps and fasten them between the joists to the subfloor using Green Glue in between. You will not have decoupling, but you will be introducing a level of damping. If you then go on to decouple your ceiling from the joists, and add DW with Green Glue to this system, you'll really start to have a great performing ceiling.