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Looking for Japanese Soaking Tub plans Answered

I'm thinking about building a Japanese Soaking Tub when I remodel my bathroom this Spring. I have a general concept of how it should be built, and I'm thinking I'll probably go traditional and use cedar to build it. I'm looking to see if anyone has some good build plans for a soaking tub, specifically how to seal the tub so the water stays in the tub. 

I tried uploading a picture to give you some idea, but it doesn't want to work, here's the link of the style of tub, first picture.

source: http://www.homedit.com/deep-soaking-japanese-bathtubs-turn-bathroom-spa/



2 years ago

Fourlightshouses.com has plans available. You have two choices: dry wood joinery and a pan under the tub to catch and drain the bit of leaking that occurs, or glue it and then put a waterproof finish on the inside of the tub. I plan to do this with epoxy resin on the inside (fiberglass cloth is optional) just like building a boat.


4 years ago

Precision is what you need, plus a tounge and groove system for the boards.

For obvious reason a waterproof glue should be used.

You basically create a slide in puzzle for the tub so each single board locks into the ones around it.

There are traditional ways of getting similar results, especially when check on the traditional ways of building wooden boats.


Reply 4 years ago

Thanks for some tips. I've been looking at how some of the tubs look. Surprisingly little information on them designs wise. I've got some experience with tongue and groove, and there's a lumber mill who can cut tongue and groove to my specs, so I may have him make deeper tongues for a better seal.

I will probably have to use a sealant on the inside, and like you said a very good glue, especially when gluing the bottom and sides together.


Reply 4 years ago

I can't offer you anything in english, but have a german website that explains the process a bit:


They don't build the quare tubs like you want but I think the same principles can be applied.
Basically they glue the wood layer by layer as "rings" to get the basic shape.
All is pressed and the wood very precisely finnished so there is no gap between the pieces.
When the glue is set they final shape is done by carving and sanding followed by sealing the finnished shape.
The sealing works the same way like on your decking or other woodworks.
First impregnate the wood, followed by several thin coats of varnish to soak into the wood.
Once cured the wood is finely sanded and polished.
Still for a big square tub I would prefer a tounge and groove system over flat joints especially for the high stresses in the corner areas.