How to Build a Japanese Bath

Check your plumbing and hot water heater for size and efficiency before you make a move. You need a system that can provide around 200 gallons of hot water at any given time, which is why an ecologically-friendly waterless heater, while expensive to install, could provide time and energy savings down the road.

Measure the area you’ve selected for the Japanese tub. If you’re replacing a western-style bath, haul the old one out to clear space for the new one. Use a pencil to define an area that measures 42-inches square if you want to mimic the size of a traditional Japanese bathtub. You can make the tub larger if you so choose. Contact your insurance agent to make certain your homeowner’s policy covers this type of tub installation.

Fasten a section of green board or another waterproof drywall product to the wall you’ve selected for your Japanese bath if you’re not replacing the tub. Turn off the water supply before connecting new hot and cold water pipes to your plumbing system, and install or replace the floor drain. Re-tile the wall and mount the new pipes with brackets.

Build a double tub frame using 3/4-inch-thick sheets of melamine. You need eight sections of frame. Cut four sections to make the outer boundary of the 42-inch exterior frame and four smaller sections for an inner frame. The difference between the two determines the thickness of the Japanese bath's walls. Bolt the frames together to form squares, and coat the sides with silicone spray so the melamine sheets are easy to peel away once the cement dries.

Prepare enough cement to fill the floor and walls. Pour the bottom of the Japanese tub to create a base, then lower the smaller melamine frame into the center of the cement before pouring cement into the channel. Insert a length of PVC pipe into the tub wall that vents at both the top and the tub interior so there’s an overflow pipe in place once the shell hardens. Buttress both sides of the melamine mold so the framework holds while the cement cures.

Allow the Japanese bath to harden according to recommendations on the cement bag before removing any braces and buttresses holding the melamine framework in place. Peel away the melamine. Hang decorative hooks on the wall so you have places to stow your towel and robe. Attach hot and cold faucets. Place a bench into the center of the tub before filling it with water for the first time.