"a practical hands-on
   guide to bathroom


Tub Installation

                                                                                                                                                                             There are many different types of bathtubs - drop-in types, freestanding types, conventional tubs, one-piece wall/tub units, air tubs and whirlpool tubs - just to mention a few.  The discussion here will focus on the common 30" x 60" tub and we will assume that an "old" tub previously occupied the same space.  These tips can also be used for whirlpools and air tubs.

The condition of the floor is very important, so if any floor joists or subfloor needs replacement, it needs to be done first.  It's also very important that your tub is level after you install it.  That will affect water draining and your shower door installation (if you're using a shower door).

If a tub is heavy (cast iron, cultured marble, etc.), a "ladder" should be built.  A ladder is simply four structural members that are perpendicular to the floor joists under the tub to help
distribute the weight of the tub to adjacent floor 
joists.   For example:  if the floor has 2" x 10"
joists on 16" centers, the four structural members would be spaced 12"
apart below the tub and cut to a length of 14 1/2".  The "ladder" is then screwed into the joists.  I like to use screws in all our bathroom work because they hold better and can be removed easily if the need arises.

The tub with a typical tile flange should sit firmly against the wall studs and a series of drywall screws with a washer should be attached to the studs around the tub for good support.  Do not screw thru the flange - screw on top of the flange so the bottom half of the washer is on the flange.  Also, a tub must have a stringer board on the five foot length back side to give it support.  A stringer board is a 2" x 4" that is positioned directly under the horizontal "lip" on the back of the tub (and screwed into the studs) so when installed, the horizontal "lip" on the tub sits on the stringer board.

Although not frequently done, I suggest a provision be made for an access panel in the
wall on the drain side for future servicing of the plumbing (if it doesn't back-up to another
bathroom).  This can be done by framing out with wood and plywood or a "store-bought"
unit can be purchased.  This is frequently not done in our hurry-hurry society, but it can
save a lot of money and aggravation in the future for any repairs needed to the faucet.

When it comes to tub drains, we like the PVC-type that have a lift-n-turn assembly because it is the easiest to service and clean as needed.  Keep in mind that many tubs leak if the overflow washers are not properly installed - it might be a good idea to install 100% silicone caulk on the washers to reduce any leakage.  The rubber gaskets in the overflow washers deteriorate over time, so if they are siliconed in place they may be harder to remove to replace (another good reason for an access panel).  For fire safety, a heavy gauge steel sheet metal cover should be installed around the tub drain to prevent the spread of flames (in case of fire on the floor below).  These sheet metal covers are made on site and installed with short screws which are easier to use (from 
an upright position) than nails. 
When hooking up the drain to the stack, always remove old piping (especially any lead pipes)
and replace it with 1 1/2" PVC and the appropriate glue trap.  If the old pipes are not
replaced, it is a shortcut that will cause aggravation if the drain i
s slow or becomes clogged.  This is especially important if the ceiling below is finished with drywall or another permanent material (as opposed to an open ceiling like in an unfinished basement).