Pool house

What the system works out

A pool house is a building with an in-ground pool in the middle of the hall, a deck around it and a plant room across the full width at the end. You enter the pool size, the deck width and the plant room depth, and the building size follows from them. The system works out:

- the building envelope: foundations, frame, walls, roof and insulation (about 300 mm by default);

- the pool: excavation, base, shell, hydraulics, filter, heat pump and coping;

- an aluminium vapour barrier for the walls and ceiling;

- daily water evaporation and a dehumidifier with a 20 % reserve;

- labour hours: the pool, the tiled interior deck and the ceiling vapour barrier.

Humidity is the main issue

Warm water evaporates around the clock. For example, an 8 × 4 m pool with 28 °C water and 30 °C / 60 % air evaporates about 55 kg of water a day. Evaporation uses the VDI 2089 method; Lithuanian norms give no formula, so it is marked as an assumption.

- Air is kept 1–2 °C warmer than the water, humidity at 35–65 % (HN 109 good practice).

- The hall must be at lower pressure than the house: more air is extracted than supplied (STR 2.09.02 p. 12.1).

- Condensation in the envelope is not allowed: a designer must calculate the moisture state of the walls and roof.

- Window glazing U should be about 0.9 W/(m²K) — with a higher U the glass will mist in winter.

Electrical zones

The electrical rules divide a pool room into zones. Zone 1 extends 2 m from the water's edge — only 12 V equipment is allowed there. Sockets may be no closer than 1.25 m to the water, with 30 mA protection. If the deck is narrower than 2 m, the whole hall up to the walls is zone 1, so the panel, transformer and dehumidifier go in the plant room. All metal parts are joined by equipotential bonding.

Purpose, span and energy

- A pool house next to a home is an ancillary building, an accessory to the house. It may not contain sleeping places.

- There can be no supports over the pool, so the building width quickly exceeds the 6 m span — it is then no longer a simple structure and needs a building permit.

- A heated building with more than 50 m² of useful area must meet energy class A++.

- The interior deck in the estimate: flexible cementitious waterproofing with corner tape, anti-slip R11 tiles, C2TE S1 adhesive and epoxy grout. Prices and consumption come from the market and the manufacturers' data sheets.