John Sayers' Recording Studio Design Forum Archive

I'm at the stage of adding rc to the ceiling. This may be a dumb question. The lengths are 8ft long - should the ends overlap slightly or just butt upto each other. The ends often meet between joists

I know either way isn't going to be a sound control factor - but just thinking about the right way to do the construction.

Andrew, I'm not sure why you're having ends meet other than at joists, unless the room is odd-sized - normally, with standard joist spacing, either 16" or 24", 8 foot channel would always come out even.

Regardless, the joints need to overlap on a joist, even if you have to trim the channel back. An inch or two, whatever lines up the mounting holes, is enough overlap. You can use one screw through a pair of channels where they overlap. If you're lucky enough to get two screw holes to overlap at a joist, even better.

On a ceiling, the recommended orientation of channel is across the joists at 90 degrees.

It's even more important on a ceiling than a wall, that you use the right screws - Type W for going into wood studs thru the holes in the channel, and Type S (for steel studs) when fastening thru the wallboard into the channel. Be sure and mark the joist locations with tape or something temporary, so you can MISS the joists with ALL screws from wallboard to channel, just in case one is long enough to "short out" the channel riser to the wood joists.

Hope that helped... Steve

Thanks. The 1st joist distance is only about 15 inches - that is what had the 1st length not joining over the joists and had me wondering - I guess I should avoid doing this at 2am !