DIY Hot Wood Fired Tub +20 for Relax in Garden

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About: I love to make DIY projects with my son

Everyone likes hot baths, but what about having them in Your garden, when You see the sunset or the stars at the sky ? That's an idea!

I'll show You how to built really simple hot tub in the garden/backyard. You can think about it as cheap jacuzzi ;-)

The project isn't hard, although time consuming, because You need to wait few days when the foundations will dry, the plastering will dry etc..


Supplies:

Needed parts:
- sand, lime, cement - for mortar and plastering

- red bricks - special bricks and mortar for building ovens (temperature resistant) - silicons: waterproof and heat resistant - bathtub - metal corners for plastering

Step 1: The Idea and a Tub

Hot tub construction should be safe and looking good to fit to the rest of the garden. In My garden there are lot of white elements, so I decided to have white frame for a bathtub.

The tub should be made from metal - steel or even iron - from obvious reason. It will be heated from the fire underneath it. The fire will be close and not visible from the outside (safety reasons, kids in the garden). I don't want to build the chimney because it would not fit to the rest of my garden/it would be to heavy construction). So, the entrance to the fireplace should be big enough to sustain fresh airflow for a fire and smoke outflow from the fire.

Step 2: Foundations

I recommend to build pretty strong foundations. The brick frame will be heavy and when You put the tub on it, feel with many, many liters of water, it will be considerable heavy. To avoid the cracks, and tensions I recommend to make the steel reinforcement of the foundations.

To build foundations You need to dig a hole (30 cm is enough), put a wooden frame around it and make the reinforcement from the steel. Remember that steel has to be inside the foundations so put it on the stones (not on the bricks, because bricks in time will crack and the water will erode the reinforcement).

The frame is not only for the rectangular shape. It allows You to level the concrete surface.

Step 3: Oven and the Chimney

I started the build from making the oven from the special bricks placed with the special mortar. Bricks and mortar are temperature resistant, they won't crack in fire. Moreover, such bricks can accumulate the heat - it's very good, because even when the fire would be over, the heat from the bricks will be steel heating the water for some time.

The purpose of the oven inside the frame is also, that it's wall will protect the normal, red bricks from the heat.

As I mentioned, there will be no chimney. So the entrance for the oven have to be big to allow air to go in and smoke to go out.

In my case, the entrance has about 50x50cm. This works great.

Step 4: Bricklaying

Bricklaying seems to be something hard, but.. it isn't. You just need to keep the track of the level and the straight of the walls, so if You will use the leveling tool often - the construction will be ok ;-)

The weld between the bricks don't have to be perfect since the bricks will be later covered with plaster.

To make the roof for the oven entrance I used the frame from the boards and the mortar made from the cement, lime and some addition of heat resistant mortar. I also reinforced it with three steel rods.

Step 5: Plastering

Plastering is the hardest thing to do. It looks easy, but in fact it could be iritating if You don't know how to do it.

The most important thing is that the mortar (made from cement, lime and sand) should not be to wet. It should hold to the walls and that's all. If it's to wet it will fall down.

After putting the mortar on the walls You need to wait some time, it will dry a little bit and then it's ready for flattening with Styrofoam float.

Oh, one more thing, before plastering You need to throw at Your walls the mortar to have 'bumpy' surface. The plaster will then have better grip.

Step 6: Painting With Paint Ant the Ground

When plaster is dry, put the 'ground' on it. This is the white liquid which is the first coat before the paint.

It's application is for two reasons:

- it will close the pours and microscopic holes in the plaster, so the further paint will have better grip

- it will protect Your walls from soaking water and from cracks during winter

After protecting Your walls, they are ready for painting. Use any colour You want and the paint for the outside

Step 7: Tub Montage

To mount the tub I used mortart and two kind of silicones.

I put the fresh heat resistant mortar on the top bricks in the oven, then I put the heat resistant silicone(black one) on the top of the frame walls. Next I put the tub on the frame so it fit's to the mortar on the oven and glued to the frame with a silicone.

The last step, for protection, was to put the water resistant silicone along the tub

Step 8: The End - the Relax :)

That's all !

Now You are ready for the bath in the hot water at Your garden/backyard. Enjoy it:)

One more thing. Don't put the big fire, because even the small one is enough to heat several hundreds liters of the water in quite a fast time. Really! This construction is so efficient that I'm able to rise the water temperature for more than 20 degrees in just 35-45 minutes.

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    26 Discussions

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    winneremerald12

    7 hours ago

    Voted! Just don’t flash your neighbors

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    MimikryGadisha

    Reply 15 days ago

    very basic - but obviously working :)
    I like it!

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    coombed

    Question 15 hours ago

    Nice build, I am very inspired! Question about drainage: how do you drain the water?!

    2 answers
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    woodenProjectscoombed

    Answer 9 hours ago

    ah.. It's not shown pretty good on my pictures. Sorry.
    The tub has typical water outflow which, when open let the water through the special hole at the bottom of the wall. It can be see on the photos/video.

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    holland.j.michaelcoombed

    Answer 15 hours ago

    Good question. I'd imagine a long hose and siphon affect like you use on a fish tank rock cleaner, or machine pump with solar heh

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    JaneB6

    14 hours ago on Introduction

    Sounds like a great plan...my only question would be the difficulty of lighting a fired underneath the tub, as well as cleaning out the old ashes etc. From the look of it, the fire is a few feet beyond the entrance, and potentially to the left and right (under the tub). Getting it lit might be difficult...????

    1 reply
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    woodenProjectsJaneB6

    Reply 10 hours ago

    Yes it is difficult. Not the cleaning, because i have a small shovel with long stick, but making the fire.. You need to fire it on Your knees. But You know, this is not so bad.

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    Mimikry

    15 days ago

    really interesting ...
    I also have an old bathtub in my backyard to enjoy a hot bath while surrounded by nature :)
    Until now I cooked water in a big kettle on a wooden fire -but thats kind of dangerous and not very elegant...
    I'll think your solution through - but I might add a chimney anyway - cause smoke in my eyes while taking a bath sounds unpleasant… - and I would have to keep the fire alive while bathing - I like to take a bath for 2 hours or even longer if I have a good book and one or two glasses of wine :)
    I'm also thinking of two bathtubs next to each other - for long philosophy nights ;)
    Thanks for your instructable!

    3 replies
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    woodenProjectsMimikry

    Reply 10 hours ago

    You are right about the smoke, but You have two sollution:
    - big chimney
    - make fire, fire will heat the water&special bricks, wait until fire is gone and then make a bath with no smoke at all.

    smoke is also good for mosquitos:)

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    manicmondayMimikry

    Reply 13 hours ago

    Direct heat on your tooshy could cause unpleasant burns.

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    JP673Mimikry

    Reply 15 hours ago

    By glass’s I hope you mean bottles!?!? #LifeIsGood

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    manicmonday

    13 hours ago

    I think a chimney would make the fire burn more efficiently as it will vent waste gasses and allow oxygen to the fire.

    In fireplaces they use a rack to hold the wood allowing air flow, and in firepits they often have a buried metal pipe to allow oxygen to the fire.

    Have you considered the removal of ash? I think maybe having a metal pan in the fire area that could easily be pulled out might help.

    Just my two cents worth.

    1 reply
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    woodenProjectsmanicmonday

    Reply 10 hours ago

    You are right. The chimney would make the better and more efficient fire and eliminate the smelly smoke. But You know, My wife said - no big chimney so.. no chimney ;-) There are some things which are not under discussion ;-)

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    Jobar007

    Question 19 days ago

    Having the tub in contact with the fire doesn't create a hot spot in it?

    3 answers
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    Oskar WojakJobar007

    Answer 19 days ago

    I don't think so because steel/iron is a very good conductor and it quickly radiates heat all over the surface and then to the water.

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    woodenProjectsJobar007

    Answer 10 hours ago

    no no, it's not that bad as You are thinking.
    First of all I'm making the fire first, wait till the fire is gone and then taking the bath.
    The water is hot pretty long time, because the special oven-keeeping-heat-bricks are still heating the water, but not so hard as the fire.

    But I admin, I have a bath few times with still a fire underneath and one time it was so hot,that I need to seat on a sponge ;-)