A tiled hammam at 45 °C and full humidity: the wet heat beside the dry sauna

Hammam or sauna: a choice about the lungs, not the thermometer

A dry sauna runs at 90⁠-⁠110 °C with the humidity near zero and the heat reaches the body through the air; a hammam runs at 43⁠-⁠48 °C with the air saturated, and the heat arrives as condensation on the skin, which is why 45 °C wet feels as strong as 90 °C dry. People with sensitive airways, children who find the cabin fierce and anyone fond of the Thai habit of herbal steam choose the hammam; people who want silence and a view through glass choose the sauna. Many Thai spas end up with both, because they share the plunge pool, the showers and the plant.

Travertine, mosaic and a ceiling that leans

The room is a masonry box, tanked like a pool and then tiled. Honed travertine gives the pale, warm look and holds heat in the bench; bands of lagoon-teal glass mosaic tie it to the plunge pool outside. The ceiling is the detail nobody sees and everybody feels: a slope of one in six, or a shallow vault, so the film of condensation runs to the walls and the floor drain instead of dripping cold onto a shoulder. The bench is hollow and can carry its own heating circuit, the door is one sheet of tempered glass, and a pin-light ceiling does the lighting, because nothing at mains voltage lives inside a steam room.

Making steam in a country that is already humid

Koh Samui averages about 81 % relative humidity and Phuket 77 % (Thai Meteorological Department, 1991-2020 normals, Ko Samui and Phuket); at 32 °C that puts the dew point near 27⁠-⁠28 °C, so any cooler surface already sweats in the open air. A hammam adds a room of saturated air at 45 °C to that building, and when its door opens into an air-conditioned corridor at 24 °C the vapour condenses on the first cold thing it meets. The answers are in the plan: a vestibule or shower zone between steam room and corridor, an extraction fan that runs on for half an hour after the last session, and a vapour barrier behind the tiles so the wall behind the hammam does not become the building's wettest wall.

Six to fifteen kilowatts of steam: how the generator is sized

We size from close to one kilowatt per cubic metre of room, more for stone-heavy walls, an outside wall or a glass front, less when a heated bench carries part of the load. Up to about 6 kW the generator runs single-phase; from 9 kW we wire three-phase, as our practice and not a published threshold. Ask PEA, or MEA in Bangkok, what your meter can carry; the three-phase field note explains the meter sizes.

Water in, water out, and the cupboard next door

Where the hammam fits on a Thai property

On a resort or boutique hotel it completes the wet area with the plunge pool and the showers; in a Muay Thai or padel club it is the after-training room that needs no view; in a clinic it runs at the cooler end of the band for longer sessions. At home the two-person steam-shower size fits where a bathroom was going anyway. The configurator does not yet price steam rooms; the THB 240⁠-⁠870k range here and the layout do that job.

Keeping wet heat clean

Warm, wet and dark would grow things, so the routine is short: rinse bench and floor after the last session, leave the door open with the extraction running, let the generator flush itself, descale on the schedule the water sets, and check the silicone joints at the first-year visits. If guests pay to use the room, ask your provincial public-health office which rules apply to a hotel steam room; we put the questions on one page with the layout.