A house in the west of Ireland, and a sauna for people who already swim in the sea

The brief

The household swims off the rocks below the house in every month and wants somewhere to warm up that does not mean a drive and a changing hut. The brief reads “sauna” and, in the same sentence, “cold dip”: not a spa, a routine.

A deck that never holds water

On the Atlantic side the deck is the building. Boards are dark thermally modified timber, gapped, on adjustable supports, with a stainless drainage channel at the foot of the cabin so rain leaves rather than lingers. Fixings are 316 stainless. A deck that looks wet in a storm and still works is the right outcome.

A cabin that turns its back on the wind

• Glass away from the south-west. The corner opens towards the inlet and away from the prevailing wind, so rain runs down the glass instead of into the door seal.
• A flat roof with a membrane and falls, an overhang and a drip edge; no pitch for the wind to lift.
• Dark cladding that takes the weather and the colour of the rock behind it, and pale ash benches inside that stay comfortable to touch.

The cold dip on the same deck

A round plunge pool of about 1,100 litres, lined in slate-grey mosaic, set flush in the deck within five steps of the sauna door. The chiller sits in a ventilated chamber under the deck on the lee side of the house. In Ireland the water is cold already; the chiller's job is to hold 4 °C in July and to keep the pool from following the weather in January. See plunge pools.

What the first November should look like

The household comes back from the slipway with wet robes at ten in the morning and finds the cabin hot, because it has been on a timer since half past eight. The drain at the foot of the deck runs; the boots dry on their tray; the plunge pool, covered overnight, reads 4 °C. Nothing in that list is remarkable, which is the point.

Power, cable and planning

The cable run from the board to the deck is long, so the circuit is sized for it. The heater and the chiller each need a dedicated circuit, and the electrician confirms the board before the layout is signed. On planning, the question goes to the local authority and its answer decides the drawing: see permits compared.

This is a composite: specifications are modest and plausible, and no client, brand or review is implied.