How to Build a Japanese Soaking Tub. Soaking tubs, as used by the Japanese, offer many advantages and can be found in bathrooms of luxury homes and hotels. They are equipped with a seat that allows the occupant to immerse the entire body up to the neck in the water and stretch out their legs. Construction in the past was from wood, steel or tile, but today they also are made of fiberglass and acrylic.
Decide on the material that you want to construct your soaking tub from. Traditional Japanese soaking tubs were wood, in particular cedar. You may choose other wood but make sure that the wood will take the rough environment of being wet repeatedly over the years.
Determine the dimensions of the soaking tub and cut the material for the assembly of the sides and floor of the tub. Assemble the tub enclosure according to the plans that you have made. Take care to seal each and every joint of the enclosure, including the floor with a proper waterproof sealant. Silicone works well with most materials.
Drill a hole in the floor of the soaking tub and install a drain. Make sure you connect the plumbing to handle the emptying of the tub after the bath and seal the drain in the floor.
Install the plumbing to bring the source of hot and cold water to the top of the soaking tub. Because of the potentially large volume of water that may be required, depending on the dimensions of your soaking tub, you may want to install high flow plumbing.
Finish the outside of the tub as you like to help it blend with your decor. If you have placed it outside, make sure to seal the material against weather damage.