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Short Summary
Main recommendation: Install a new ABS waste and overflow system sized to the new 20-inch tub, measuring carefully so the drain centerline sits 8 and 1/2 inches off the wall (based on this tub's manufacturer specs), and dry-fit before gluing. The presenter argues that this matters because the new tub's overflow sits in a different location than the old 16-inch tub's, and that plumber's putty should be used instead of silicone for the drain seal.
Key Points
- Remove the old plastic waste and overflow, which was designed for a previous 16-inch tub, and replace it rather than reusing it, since its threaded connection has already been used.
- Scratch and sand all surfaces to be bonded, because adhesives, torches, or solder need a roughened surface to grip.
- Take the drain centerline measurement from the tub itself, using 8 and 1/2 inches off the wall, with only slight play in the position.
- Set the tub in place and level before fixing the overflow neck, because the tub's drain hole gives only about 1/8 inch of tolerance before leaks become likely.
- Use plumber's putty rather than silicone for the drain seal, since the presenter says putty stays waterproof and does not dry out, while silicone can lose grip on standing water.
Details Worth Noting
- Concrete instructions:
- Cut out the old waste and overflow with an ABS pipe cutter (the presenter's RIDGID tool), laying it on and rotating it.
- Sand and score the inside of fittings and pipe ends before gluing.
- Mark the drain centerline at 8 and 1/2 inches from the wall, measured by putting the tape measure through the drain hole with the tub still in its box.
- Apply ABS glue to the joints, then push and turn the fitting into place.
- Cut the pipe to length with a cutter sized for 1 and 1/2, 2, or 3 inch pipe.
- Before connecting the drain, remove the protective plastic from around the drain hole, because trapped plastic lets water seep underneath and cause a later leak.
- Apply plumber's putty to the new waste, tighten it with the tub tool, and then dry-fit the overflow without glue to check sizing before final assembly.
- The presenter reuses the existing P-trap and tee to avoid the risk of hitting a joist on the line.
- The tub is described as a Maryland tub with a plywood-reinforced skirt, sprayed fiberglass, and five-foot reinforced bars, which the presenter says is the most economical quality tub he's found on the market.
- The ABS system chosen requires exact height measurements, while more flexible adjustable systems exist but were skipped to keep costs down.
Bottom Line
Replacing the waste and overflow for a new tub is less about the parts than about precise measurement, clean bonding surfaces, and a dry fit before gluing, because the tub's drain tolerance is only about 1/8 inch.
