John Sayers' Recording Studio Design Forum Archive

I am helping my friend who is planning to convert the room above his garage to a rehearsal space. The garage was built in the 20’s and he is located in Los Angeles. He will be rebuilding the floor and reinforcing the walls below to account for the extra weight of construction and music gear. The room measures roughly 18’4” x 19’ with A frame type walls/ceiling that measure 15’3” at the peak.

My questions have to do with sound reduction and acoustics. His main concern is reducing the level of sound – he is realistic about not being able to completely soundproof the room. The walls/ceiling are bare studs with plywood covered with shingles on the outside.

For sound reduction my thoughts are to put insulation in between the studs and then drywall. The floor will be plywood with some type of flooring. Underneath the floor will be insulation with a drywall ceiling for the garage. He will also be putting up drywall on the garage walls. There will be a door at the stairs leading from the room down to the garage. Would there be a large benefit to doubling the drywall with offset seams? How about using caulking?

For acoustics, I am thinking of creating a false cloth covered ceiling about 4’ below the peak of the roof and stuffing it with insulation. Would this act as a good bass trap? Would we be better off hanging some rigid fiberglass?

Thanks for your help!

Here is the side view.

For the outside roof/walls, you might want to consider adding more mass between the studs similar to this

http://www.johnlsayers.com/phpBB2/viewtopic.php?t=2478

I'm needing to get some sleep but you seem to be on the right track - basically, you want 2, and only 2, leaves of mass between you and the world, separated by ONE air gap that's filled with insulation. More than that will actually WORSEN your isolation - here's a good explanation of what's necessary -

http://www.domesticsoundproofing.co.uk/tloss.htm

Note the wall examples at the bottom of the page - specifically the 40 dB wall compared to the 63 dB one - also note that each time you REMOVE a leaf and WIDEN the air gap, you improve isolation.

For your ceiling, I'd go with the heavier rigid fiberglass - this peak will kill you if you don't kill it, but it will make a good bass trap with rigid fiberglass or rockwool across it... Steve