A.Don Wheeler, a custom
builder in Anaheim, Calif., who frames primarily with steel,
responds: Though lighter 25-gauge steel studs are plenty
strong for framing interior walls, I usually use 20-gauge steel
studs. These feel a little more substantial and tend to suffer
less abuse around the job site. The following method of
reinforcement will work with either size of steel
framing.
First, you want to strengthen the wall behind the sink. To do
this, "bridge" the studs with a stud or track cut so that it's
equal to the length of the wall. Holding this cut stud (or
track) in position with the web facing out, mark the top and
bottom flanges where they intersect with the wall stud flanges.
Using a circular saw fitted with an abrasive blade, make cuts
in the flanges on these marks flush with the web.
If you're using 25-gauge material, you can then just bend the
cut sections of flange over so that they lay flat on the web.
With heavier-gauge material, you'll need to cut the flange
sections away with the saw.
Next, place the stud on the front of the wall approximately
midspan (so that it won't interfere with any electrical boxes
or other wall openings) and screw the web face to the flanges
of the vertical stud wall.
I'd also recommend bridging the back of the wall the same way
with another stud. This gives the vertical studs more strength
and helps prevent them from twisting.
Now you need to bridge again to create a place to screw in the
mounting hangers, this time between the two vertical studs that
will support the sink. Be sure this bridging is positioned so
that the sink-mounting hangers will be at the correct height.
Here, I would not recommend using 25-gauge material; instead,
to prevent the hangers from pulling out, use a minimum of
16-gauge framing.
You could also use 2x10 or 2x12 blocking, cut to fit tightly
between the two opposing webs. On one side, you'll need to
screw through the flange into the end grain of the 2-by
blocking; I'd use at least four screws to do this.
On the other stud, you can screw through both the web and the
flange (see illustration).