Steam rooms in indigo mosaic and coral stone

The tank

Liquid membrane over the slab and up the walls past the ceiling junction, taped at every corner, screed falling at least 1:50 to the drain, then mosaic or stone. The ceiling pitched 3 to 5 degrees or domed so condensate runs to the walls.

Coral rag and old lime walls need particular care: they are absorbent, so the membrane has to be continuous and properly detailed at every junction with the existing structure.

Ventilation is the design decision

Mechanical extract with a long run-on, ducted out, sized for several air changes after a session. On Zanzibar we specify a humidistat rather than a timer, because the outside air varies and a timer cannot know.

Extract that terminates in a ceiling void rather than outside is the worst outcome available and we find it regularly in other people's work.

Water

Island water varies and many properties are on borehole or rainwater. We test at the property before specifying the generator, because the descaling interval depends on it and a scaled generator on an island is a long wait for a replacement.

In short

• Membrane continuous and detailed into absorbent coral and lime walls
• Humidistat extract, ducted out — a ceiling void is not outside
• Water tested at the property, including borehole and rainwater supplies
• Indigo mosaic and coral benches priced against porcelain honestly