How to install walk-in tubs: 8 steps to a new bath

Part 1 of this guide for installing walk-in tubs discussed how to remove your existing tub. As you look at the space now, it should be clean and have the wall studs exposed up past where the top of the new walk-in unit will be located. If there will also be surround panels installed, the studs should be exposed up past the tops of them as well.

Before moving the new unit into the bathroom, do some quick measuring to ensure no other fixtures will have to be temporarily removed in order to sit it in place. In most cases, if you were able to get the old tub out without a problem, the new unit should fit.

A guide for installing walk-in tubs

This guide is generic, but should work for just about any walk-in tub. However, manufacturers such as American Standard and others usually include instructions for their specific models. Read those as well prior to starting the project. Once again, if you doubt your abilities at all, contact a contractor to handle your walk-in tub installation. But for those with the DIY experience to complete the project properly, here are the steps involved:

1. Install ledger board - Determine where the top of the tub flange will hit on the wall studs and make a mark. Use your four foot level to extend this mark onto all the studs the tub will rest against. Then measure down one inch from that mark and make another mark. Extend this mark using the level onto all of the framing as well. Attach a 2 x 4 piece of lumber so that the top is even with the bottom mark all the way around. The 2 x 4 can be nailed or secured using drywall screws and a drill. This ledger board will support the tub edges.
2. Install shoe fitting - The drain lines that were removed from the underside and overflow of the old tub should now be installed on the new walk-in tub. The easiest method for doing this is to lay the new unit on its side. If there are any differences in measurements from the overflow to the drain between the new and old units, you may need to make some adjustments that might involve putting in a new piece of pipe. But in most instances, the old shoe fitting should fit the new tub. Attach the tub drain and overflow cover to hold the shoe in place. Always use plumber's putty liberally when making connections.
3. Install mortar - Mix the mortar. Using the trowel, spread it evenly on the subfloor in the area where the walk-in tub will be placed. The mortar should be about two inches thick. Take care not to get any in the drain line. Once you're done placing the mortar, remove the rag that was installed in the drain line during the prep stage.
4. Install the walk-in tub - You are now ready to sit the walk-in tub into place. It's usually much easier to perform this step with a helper as it may avoid damage to the tub or your wall coverings. Lift the tub up and sit it down into its space taking care that the shoe fitting lines up with the drain line coming up from underneath. The tub edges should be sitting on the ledger boards. Remove any mortar visible along the exposed tub edges.
5. Level and secure the walk-in tub - Use your four foot level along the top front of the tub and install wood shims as needed to level the unit from right to left. Then use the torpedo level on an end ledge, or the four foot level if it will fit, to level the tub from front to back. Again, install shims as needed. Once the unit is level, secure it to the wall studs by hammering galvanized nails through the tub flange. You may find it easier to use a drill and bit to put holes in the flange first.
6. Secure the drain - Once the tub has been nailed in place, you can secure the drain to the shoe fitting either through the access hole in the adjacent wall or the hole in the ceiling underneath.
7. Install the faucets - Install new faucets or those removed from the old tub. Installation is just the reverse of removal and can normally be accomplished with just a screwdriver.
8. Turn water on - You can now turn the main water supply lines back on, but be sure to check for leaks at the supply and drain lines before closing up any holes.

Depending on the walk-in tub model, you may now need to install surround panels. Follow the manufacturer's instructions for attaching them to the tub unit and in most cases, the top flange will need to be nailed to the wall studs. You can then install any cement board or other water resistant material needed to patch along the top of the tub or surround.

Congratulations - you have now completed your walk-in tub installation. The only thing left to do now is enjoy your new bath!