The Japanese order: wash first, then soak
A Japanese bath follows a simple sequence. You wash and rinse seated on a low stool in an open wet room with a hand shower and a floor drain, and only then step into a deep tub that is used for soaking alone. Because the tub water stays clean, it can be kept warm under a lid for the next person. For a spa bathroom we usually design the tub for a water level of 50 to 60 cm, enough to sit upright with the water at shoulder height, and place it so you look out rather than at a wall. The wet room is tiled or clad in stone from floor to ceiling, with a continuous slope to the drain, a niche for bottles, a bench and good light at seat height. The layout is the same in an Amsterdam canal house as in a villa in Pozuelo de Alarcón; only the dimensions change.
Hinoki, other woods and stone: how materials age
Hinoki, Japanese cypress, is the classic wood for a Japanese tub, valued for its scent and warm touch; other timbers are used for walls, ceilings, duckboards and benches. Wood in a bathroom asks for care. One Japanese maker of hinoki tubs advises draining and wiping the tub after each use, airing the room, and renewing the protective treatment every six months to a year. The same maker warns that underfloor heating or a long period without use can dry the wood out so that it shrinks, and recommends leaving a bucket of water in the tub under the lid; with regular care, it gives about 15 years as a guideline for replacement. Stone and porcelain tiles need far less attention and suit the floor and walls of the wet room. A sensible combination is stone or tiles where water runs, and wood where you sit and look.
Structure and hot water for a deep tub
A generous tub of 130 by 80 cm inside, filled to 55 cm, holds about 570 litres, roughly 570 kg before the tub, the bather and a stone surround are added. Spain's building code uses an imposed load of 2 kN/m², about 200 kg per square metre, for residential floors, so a filled deep tub is far beyond the general load a floor is designed for. On a concrete slab that is often manageable; on the timber floors of a canal house or the upper floor of a villa, a structural engineer checks the beams and, if needed, designs reinforcement. Hot water is the second calculation. A CW6 gas combi boiler delivers about 20 litres a minute at 40 °C, so 570 litres takes close to half an hour. With a heat pump, hot water comes from a storage cylinder that needs time to reheat, and an 80-litre electric termo, as used in many Spanish flats, gives only about 145 litres at 40 °C. We size or add a cylinder before the tub size is fixed.
Ventilation, heating, light and the view
A hot, deep bath and a sauna release a lot of moisture. Dutch new-build rules ask for at least 14 dm³/s of extraction from a bathroom, discharged directly outside, and Spain's CTE DB HS 3 sets 6 to 8 l/s per wet room depending on the size of the home. For a spa bathroom we treat these as minimums and size the extraction for the actual use. Underfloor heating keeps stone and tiles comfortable underfoot and helps the wet room dry, although a hinoki tub then needs the care its maker describes. Lighting is layered: soft, low light around the tub, brighter light at the washing place, with fittings suitable for each bathroom zone. Where the house allows, we orient the tub towards a Japanese garden, courtyard or terrace, with glazing and screening that keep your privacy.
Adding a sauna and a cold shower
A sauna fits naturally next to a Japanese bath: you go from the heat to a cold shower a few steps away and then to a place to rest. Heater power is matched to the volume of the cabin; Harvia, for example, rates its 6 kW Vega heater for rooms of 5 to 8 m³, on a single-phase 230 V connection with a 35 A fuse or on three-phase 400 V. Glass fronts and stone walls count as extra volume, so the heater grows with the design. The heater maker asks for the air in the cabin to change at least six times an hour, which we coordinate with the bathroom's extraction. Indoors, the cabin can share the wet room's waterproofing and drain; in the garden, foundations, the cable route and local rules come first. The electrical connection is made by our licensed electrician partner.
Approvals: VvE, comunidad and listed buildings
In a penthouse or flat, the owners' association is part of the plan. In the Netherlands, the deed of division and the VvE rules decide which works need approval; drains, supply pipes, structure and new tiled floors with acoustic requirements often do. In Spain, article 7.1 of the Ley de Propiedad Horizontal lets owners alter the installations of their own flat when safety, structure, exterior and other owners' rights are unaffected, and requires them to inform the comunidad's representative first; works on shared elements need the comunidad's agreement. A detached house gives more freedom, unless it is listed: changes to a Dutch national or municipal monument generally need an omgevingsvergunning, and protected buildings in Spain follow the town hall's catalogue and procedures. A garden sauna may need its own check. We look up your address during the survey.
Where we work, how the project runs and what it costs
We design and build Japanese bathrooms in Amsterdam (including Amstelveen), Het Gooi (Laren, Blaricum), Wassenaar near Den Haag, Bloemendaal and Aerdenhout near Haarlem and the Utrecht area, and in Spain in Madrid (La Moraleja, Pozuelo de Alarcón, Aravaca), the Barcelona area (Pedralbes, Sarrià-Sant Gervasi, Sant Cugat, Sitges) and around Valencia. A project runs in clear steps: site survey, design, fixed quote, then the build, led by a Japanese engineer and carried out by Japanese technicians. Every wet area is flood-tested for 24 hours before tiling, and hidden work is photographed so you receive the record at handover. Indicative prices: a Japanese bathroom from €24,000 including VAT and a home sauna from €9,800, with a fixed quote after a site survey.
