Plunge Pool: Size, Depth, Roof Load and How It Is Built

A plunge pool is a small permanent pool kept at a comfortable temperature for dipping and cooling off. A cold plunge is a compact basin chilled on purpose with a dedicated chiller. Both need waterproofing, circulation and filtration, but the cold plunge adds a chiller and insulation to hold the low temperature.

Sauna Dekor Spa Solutions engineering team, Istanbul · project and press enquiries: Alican Aykaç, Managing Partner

Last updated: 12 November 2026

Every 1 m of water depth puts 1,000 kg on each square metre of floor. That one physical fact explains why a plunge pool on a villa roof is a structural project before it is a pool, and why the ground-floor version is usually the simpler build.

Table of contents

• What is a plunge pool?
• How big should a plunge pool be?
• How deep is a plunge pool?
• How heavy is a plunge pool, and can it go on a roof?
• Concrete, stainless steel or prefabricated: which shell?
• What equipment does a plunge pool need?
• What changes for a plunge pool in the Gulf heat?
• How is a plunge pool built, step by step?
• Frequently asked questions
• Sources

A plunge pool is a smaller, permanently installed swimming pool. It is built for a dip rather than for lengths: you step in, cool off, sit on a ledge or float. In technical terms it has the same 3 parts as any pool, a waterproof shell, a circulation and filtration system, and water treatment.

The difference from a full pool is scale and purpose. A full pool is planned around swimming, so its length leads the design. A plunge pool is planned around the space it has to fit, a courtyard, a terrace, a roof or a narrow side garden, and around how many people will use it at once.

The name causes one common mix-up. In a spa brief, “plunge” can also mean a cold plunge, the small chilled basin used after a sauna. That is a different build with a chiller; our page on the ice bath and cold plunge in Dubai covers it. This guide is about the small pool.

As big as its use, not as big as the plot allows. There is no single standard size: the length and width follow from 3 inputs, the number of people who will be in the water together, the seating or steps inside the shell, and the free deck needed around it for access, cover and service.

We start the drawing from the inside. Steps, a bench along one wall and a clear standing area take a fixed share of the floor, and the rest of the basin is drawn around them. A pool that will mostly be used by 2 adults at sunset is a different shape from one where children will play.

If the owner wants to swim rather than to dip, the brief has changed and a long narrow lap pool is the better answer. If the plot can take a full pool and swimming matters, our page on swimming pool construction in Dubai covers that build.

Deep enough to stand with the shoulders near the water, and no deeper than the use needs. Depth sets 2 things at once: how the pool feels and how much it weighs, because every 100 mm of extra depth adds 100 kg to each square metre of the floor below.

Most plunge pools are a single depth rather than a sloping floor, with a bench or ledge where people sit. Steps along one side make the pool usable for older guests and children; a handrail beside them is a small addition that matters on a wet stone deck.

Because a plunge pool is not for diving, depth is a comfort and safety decision, not a sporting one. We set it with the client on the drawing, then check it against the structure and the drain before anything is cast.

Heavy, because water is heavy: 1 cubic metre weighs about 1,000 kg. A plunge pool with 1 m of water puts about 1,000 kg on every square metre of its floor, before the shell, the lining, the coping and the people are added. On a roof, that load is the first question, not the last.

At ground level the load goes into a slab on prepared ground, which is usually straightforward. On a roof terrace, a podium or an upper floor, the building’s structural engineer confirms the slab, the beams and the points the shell bears on. We supply the engineer with the numbers: footprint, water depth, filled weight and the position of drains and pipes.

A roof pool also has to stay watertight above someone’s ceiling. That means a continuous waterproofing membrane under and around the shell, a tested drain and an overflow route, all agreed before the shell is built. Our 5-year warranty on structure and waterproofing applies to the work we deliver.

3 routes, chosen by site and finish. A cast concrete shell can take any shape and any tile or stone, and suits gardens and new-build roofs. A stainless steel shell is made in a workshop and set in place. A prefabricated shell is quickest but fixes the size and shape to the maker’s range.

For a villa courtyard or a new terrace we usually build in concrete, because the pool can follow the architecture exactly: a bench on the shaded side, steps where the house door is, a coping in the same stone as the deck. The shell is waterproofed and then lined, most often in glass mosaic or stone.

Where an existing roof cannot take wet concrete work or the access is tight, a workshop-made shell can be the better route. The choice is made after the structural check, because the route in for a finished shell, gates, stairs or a crane, decides what can arrive in one piece.

How a factory-moulded shell is delivered and installed is covered on our prefabricated pool page.

The same 4 systems as a full pool, sized smaller: a circulation pump, a filter, a disinfection method and, in most climates, a heat pump. Filtration and disinfection are 2 separate jobs. The filter removes particles it can catch; the disinfectant deals with what a filter cannot.

A plunge pool holds far less water than a full pool, so each person who gets in changes the water chemistry more. That is why its dosing has to respond quickly and why a cover between uses helps: it keeps sun, leaves and dust out of a small volume of water.

The plant needs a home: a small plant room or an equipment enclosure within a short pipe run, with a drain for backwashing and emptying, a dedicated electrical supply, ventilation for the heat pump and service access to every valve. Our note on how to maintain a pool covers the routine once it is running.

The water gains heat for much of the year, so cooling matters as much as heating. A heat pump moves heat rather than making it, and many units can run in reverse, so 1 machine can warm the pool in the cooler months and take heat out of it in summer.

Shade and a cover do much of the work before any machine does. A pergola, a canopy or the building’s own shadow reduces the sun on the water, and a cover between uses limits both heat gain and evaporation. We place the pool on the drawing with the sun path in mind, not only the view.

Indoors, the questions turn to air: a warm water surface in a closed room raises the humidity, and the room needs extract and dehumidification so that cold surfaces do not run with condensation. Our page on the indoor pool in Dubai sets out that climate control.

In 8 steps: survey, design, structural check, shell, waterproofing and testing, lining, plant installation, and commissioning. The order matters most at step 5: the shell is filled and left standing as a watertight test before any mosaic or stone goes on, so a leak is found while it is still easy to fix.

1. Survey: the site, the access route, the drain point and the electrical supply.
2. Design: size, depth, steps, bench, finishes and the plant position, on a drawing the client signs off.
3. Structural check: by the building’s engineer for any roof, podium or upper floor.
4. Shell: cast concrete or a workshop-made shell, with pipe and fitting positions fixed.
5. Waterproofing and water test: membrane, then a full fill before finishing.
6. Lining and coping: mosaic or stone inside, stone coping and deck around.
7. Plant: pump, filter, disinfection and heat pump connected and labelled.
8. Commissioning: water balance, controls set and the routine explained at handover.

Beside the pool, the same project can include a hot tub or a sauna; our jacuzzi page for Dubai covers the warm-water option. On the work we deliver, the terms are a 24-month warranty on workmanship and manufacturing and a 5-year warranty on structure and waterproofing.

Sauna Dekor has designed, manufactured and installed saunas, steam rooms, hammams, pools and cold plunges since 1987: 40 years of manufacturing in Istanbul, in our own facility in İkitelli OSB, with a team of 19 employees and 5,000+ projects in 41+ countries. We work under TS EN ISO 9001:2015, certificate no. 202025106. Our offices are in Istanbul (İkitelli OSB), Dubai (Latifa Tower) and Boston (66 Long Wharf, Unit 4B). We also have representative offices in Bodrum, Monheim am Rhein (Germany), Haarlem and Doha.

We build pools turnkey: excavation or shell, waterproofing, the equipment package, installation and commissioning. Pumps, filters, heat pumps and dosing units are their manufacturers’ products, and their conformity and warranties belong to those manufacturers. Our Diplomatic Club project in Doha shows pool and spa work of this scale.