Why a deeper tub needs less floor
The plunge tub we usually build is a lie-down tub: 168 centimetres long, 66 deep, entered with the legs straight. It is comfortable, and it eats 168 by 82 centimetres of floor — 1.38 square metres — which many Jakarta terraces and most Bali villa side-yards simply do not have. An ofuro turns the geometry through ninety degrees. The water stands 78 centimetres deep, you sit on a seat moulded into the wall at 42, and the surface stops at your shoulders. The footprint falls to 0.95 square metres for exactly the same volume of water, and being round it fits corners that will never take a 1.7-metre box.
The honest cost is that you cannot straighten your legs. For many people that is an improvement rather than a loss, because a seated position is easier to get into and out of, which matters most at 4 degrees when you want to leave quickly. Above 185 centimetres of height the knees fold quite deeply, and we would rather you sat in one at the workshop before ordering than found out afterwards.
| Size | Volume | Diameter outside / inside | Water depth | Footprint | Filled weight |
|---|
| Single | 320 L | 100 / 82 cm | 72 cm | 0.79 m² | 450 kg |
| Standard | 400 L | 110 / 92 cm | 78 cm | 0.95 m² | 550 kg |
| Roomy | 520 L | 120 / 102 cm | 80 cm | 1.13 m² | 695 kg |
Built like our teak tub, with one change
The construction is the one described on the teak ice bath: an 8 mm vacuum-formed acrylic liner holds the water, 40 mm of polyurethane wraps the liner, and reclaimed teak staves 40 by 120 mm stand outside all of it as a skin. The timber may swell and shrink as the climate pleases, because the timber is not what holds the water. That rule does not bend on a tub running at 4 degrees: 29 degrees of difference across a single stave will open any joint within two seasons.
The change is the seat. It is formed as part of the liner rather than bonded in afterwards, because a bonded joint 42 centimetres down carries about 4 kilopascals every time the tub is full, and that is the leak we most often find in deep tubs built by other people. The cavity under the seat is foamed with the rest, so there is no thermal bridge at the one surface in longest contact with the body.
Seat height above the floor of the tub42 cm
Seat depth34 cm
Rim radius12 mm, hand-sanded
Rim height above the deck92 cm
Stepstwo 316 stainless treads, standard on every ofuro
Grab rails32 mm round teak on two sides
Feet35 mm 316 stainless, air gap underneath
Cold at 3 degrees or warm at 40, in the same tub
An ofuro in Japan is a hot tub, and some buyers order ours for exactly that. Others order it as a cold plunge purely because the shape fits a small terrace. Since our chillers run from 3 to 40 degrees, both can be true of one tub: 4 degrees before work, 39 at night. If that is the pattern you actually want every day, the size and the kit are set out under the heating and cooling chiller.
For cold-only use all three ofuro sizes land on 2 HP in the lowlands, the same as a 400-litre lie-down tub. The load is lower, though, and it shows on the bill: the water surface of a 400-litre ofuro is 0.67 square metres against 0.88 for a lie-down tub of the same volume, and evaporation and condensation — the two largest terms in the model — both follow that area. The holding load is 439 watts against 516, a difference of 77 watts or about Rp 28,000 a month.
Looking after the timber
- Tung oil twice a year, about 250 millilitres a coat and two hours of work. Without it teak goes silver-grey in 8 to 14 months. The grey does no structural harm, so this is a preference rather than an obligation.
- Retension the stainless bands at three months, at the end of the first dry season, then once a year. 18 Nm, we leave the key, five minutes of work.
- Rinse the 20-micron cartridge fortnightly. On an ofuro it loads faster than on a lie-down tub, because the same water turns over in a narrower, deeper column.
- Do not let the underside stay wet. The 35 mm stainless feet leave an air gap, but an ofuro tucked into a closed corner with no air movement should be shifted and dried once a month. This is the step owners skip, and wet lower staves are the commonest cause of mould we are called out to.
When an ofuro is the wrong tubIf you are over 185 centimetres and immerse for more than five minutes, the folded-knee position will start to bother you, and a lie-down shell such as the terrazzo ice bath makes more sense. If the tub will be used by older members of the household or by anybody with bad knees, a rim at 92 centimetres is high — we can drop it by sinking the ofuro 25 centimetres into the deck, but that is civil work that has to be planned from the start. And an ofuro is not a two-person tub: we were asked once, and the result was a 1.7-metre shell that had thrown away the whole point of the footprint. For two people, build the two-seater properly.
Price, lead time and shipping
A teak ofuro of 320 to 520 litres runs Rp 45-72 million for the complete shell with liner, insulation, seat, bands, lid, steps and circulation pump. The chiller is separate, from Rp 48 million for a 1 HP unit. Lead time is 14 working days for Java and 10 for Bali, and outside Java an ofuro is actually easier to ship than a stone tub: staves and bands travel flat, the liner in its own crate, and our technician assembles it on site in a day. Routes and freight costs are under inter-island delivery.
Why teak rather than hinoki?
Hinoki does not grow here, and once import freight is added the price multiplies without any certainty that it lasts better in 80 per cent humidity. We use reclaimed Javanese teak that has already stood for decades and finished moving, kiln-dried to 12 per cent before it is resawn. If you specifically want hinoki we can source it as a bespoke job and we will quote the real number.
Can two people use it in turn without changing the water?
Yes. The chiller's built-in ozone and the 20-micron cartridge carry two or three people a day. Above that we add UV sterilisation. We suggest changing the water in a 400-litre ofuro every six to eight weeks in domestic use, and draining is quicker than on a lie-down tub because the outlet sits at the deepest point.
How much of me is actually under water?
There are 36 centimetres of water above the seat, and that is what decides it. For somebody 165 to 180 centimetres tall the surface sits between the collarbone and the base of the neck. We move the seat up or down by 4 centimetres at no cost if you give us your height with the order.
Can an ofuro be sunk flush with a deck?
Up to 25 centimetres, and it is the most common request because it brings the rim down to 67 centimetres and makes the tub far easier to enter. What has to be prepared is a pit with a base slab, a drain at the lowest point and 40 centimetres of service access on one side. Your own builder can do the civil work from our drawings; the requirements are under installation.
Can single staves be replaced if one is damaged?
Yes, and that is the advantage of a separate skin. The bands come off, the damaged stave lifts out, a new one goes in, the bands are retensioned. One stave is about Rp 380,000 fitted. On a solid-timber ofuro that holds its own water, one cracked stave means the whole tub leaks.
