Swimming pool construction stages: the order of 12 steps from site survey to stage payment

Hotel and residential complex pools keep the same order; only the durations and the number of documents increase. The durations are the average ranges of the projects we have commissioned since 1993; ground, climate and the permit process change these ranges on every project.

The rows of the table most often skipped are 2, 7 and 10. When the ground investigation is skipped, shell thickness and drainage are set by guesswork; when drainage is skipped, groundwater lifts the empty shell; when the water-tightness test is skipped, a leak ends up under the finish and the finish has to be removed to find it. None of the three is an expensive step; what is expensive is the repair after they are skipped.

The intended use decides the pool type: a skimmer pool needs less balance tank capacity and pipework, while an overflow pool is preferred in hotels and design-led villa projects for its surface cleaning and appearance. Because this choice sets the shell geometry, the balance tank and the size of the plant room, it is settled before the design.

The ground investigation answers two questions: the summer and winter level of the water table, and the bearing capacity of the soil. Under Archimedes' principle, when the water table rises above the pool floor, the empty shell is pushed upwards with a force equal to the weight of water it displaces; for an 8 x 4 m pool, a 1 m difference in water table means a force in the order of 32 tonnes. This figure puts the shell toe, the hydrostatic valve and the perimeter drainage into the design at step 4. The construction drawings also include the seismic joint between pool and building, the pipe penetrations and the reinforcement plan; for projects that need a permit, this file is submitted to the municipality. We prepare the municipal process and all the structural, electrical and architectural drawings required for the pool permit.

Groundwater is observed and photographed during excavation; a dry excavation does not mean dry ground. At the bottom of the excavation, perforated pipe and a gravel bed for perimeter drainage are laid so that they connect to the sump; blinding concrete is poured over them and the main drain line is taken through the blinding.

The shell concrete is the longest technical step on its own. A double layer of reinforcement is tied, cover spacers are fixed, a waterstop is placed in the floor-to-wall joint, and the skimmer, inlet nozzle and main drain sleeves are fixed to the reinforcement. The concrete arrives as class C30/37 with a water/cement ratio below 0.45; no water is added to the mixer on site, and samples are taken at every pour. Sprayed concrete or cast-in-formwork is chosen according to the design, and in both cases the shell is cured by keeping it wet for at least seven days. The structural work closes with the concrete sample results and the pour record; this stage payment depends on the concrete being poured and the samples being taken.

Each line is capped and pressure tested, and the test record becomes an annex to the stage payment; a leak in a buried line cannot be found later without lifting the paving. The pump, filter, heat pump and dosing equipment are installed in the plant room at this step; the chemical store is planned as a separate, ventilated space away from the pump room.

Waterproofing is applied over the shell as a cement-based flexible layer, with tape at the corners and pipe penetrations. The pool is then filled and the water-tightness test is carried out: the level is monitored for 48 hours, the evaporation allowance is deducted, and the remaining loss is a leak. No finish starts before the test is passed; the rule exists because of the cost of repairing a leak that shows up after the finish is laid.

Ceramic or glass mosaic is laid with pool-grade adhesive and the joints are filled with epoxy grout; the coping stone and surround paving slope away from the pool and are connected to a rain gutter and the garden drainage. The finish checklist covers joint gaps, waterproofing under the coping stone and paving falls. This step looks the longest in duration; material supply and grout curing set the programme.

Commissioning starts with the first fill: the water is balanced (alkalinity, pH and calcium hardness, in that order), the first filter backwash is done, automation and dosing are set and the heat pump is brought into service. Operator training is given to the owner or the technical staff; the test logbook, winterising instructions and chemical storage rules are part of this training. The handover certificate is signed together with the commissioning report, as-built drawings, equipment warranty documents and the operating manual; the final stage payment depends on this file.

The first is that each step produces the input for the next: the ground investigation sets the shell, the shell sets the pipework, the pipework sets the waterproofing, and the waterproofing sets the finish. The second is to put a cheap test in front of every job that is expensive to undo: a pressure test before burying, a water-tightness test before the finish, a commissioning report before handover. Tying stage payments to these records keeps the sequence intact on site as well; payment moves with evidence.

This discipline has been carried over to pool construction from the site practice of water tanks and treatment structures. A reinforced concrete pool shell is a structure, and it proceeds like one: ground first, then design, then structural work, then finishing. The programme of a pool project is read from this sequence too; the way to shorten it is not to skip steps but to finish steps 2 to 5 before the excavation season.