Date: Fri Mar 2, 2001 6:51 am
Subject: Re: Mounting double layer drywall on RC
--- In acoustics@y..., SRF7@a... wrote:
> In a message dated 3/1/01 8:50:31 PM Eastern Standard Time, ron_v0@y...
> > I have heard various opinions on mounting a second layer
> > of drywall on RC channel. One source says to screw only into
> > the first layer of drywall without hitting the RC. I've also heard
> > that you should use longer screws and go into the RC.
> > Anybody know the correct method?
> > Thanks!
It is extremely important to install RC correctly. Improper
installation will ruin any advantage gained from using it in the first
There are a few simple procedures you need to follow when using RC
channel. On walls and ceilings, the channel should be mounted at a
right angle to the framing. On walls, mount with the narrow flange
along the bottom and the larger flange up. This allows the drywall?s
weight to draw itself away from the framing. Also, all flanges should
be pointing in the same direction.
When fastening the final layer of drywall, the screws are to be
connected to the channels in-between the studs or joists. It is
absolutely critical not to "short out" the resilient channels by
screwing long screws into the wood studs behind them. This rigid
connection would destroy any benefit. Also make absolutely sure screws
go into the RC channel - not direct into the drywall behind it. Every
screw that goes direct further decreases the wall's efficiency.
Finally, make absolutely sure that you use spacers top and bottem, at
least 1/8" at the top and 1/4" at the bottem (allowing for possible
sag). Fill these gaps liberaly with caulk. If you apply mud /
plaster over the drywall, the same applies. Any ridgid contact with
floor, ceiling, wall behind it will reduce the efficiency a helluvalot