- Q.We’re installing a fiberglass tub unit
over a truss-framed floor. A small plan change moved the tub so
that the overflow pipe lines up with a floor truss below.
There’s just enough room to run the drain above the
truss, but is it okay to run the drain horizontally for a foot
or so beyond where the overflow standpipe connects before
putting in the trap? The code we use says there can be no more
than 24 inches between the drain and the trap weir, and
to place the trap “as close as possible” to the
drain, but what does this mean in terms of horizontal
distance?
A.Mike Casey, a licensed plumber in Connecticut and
California and coauthor of Code Check Plumbing,
responds: Most code inspectors will allow 24 inches of
horizontal distance before the trap where necessary, but be
sure to check with your local official. There also are offset
tub drain-overflow assemblies with side or rear outlets that
may help overcome framing obstacles.
Tub Drain Distances