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Knowing each step to build a swimming pool is an asset to remain serene during its realisation. Studies prove that an underground swimming pool brings from 5 to 25% more value to a house, but it should not be a source of stress.

The choice of location

You don’t put a pool just anywhere in your backyard. For a good integration, it is preferable to choose a location that will not disturb the natural terrain profile too much.
You should choose the sunniest location that is the most sheltered from the wind. The proximity of deciduous trees should be avoided.
In this post, you will find the basics for choosing the best location for your pool, but don’t forget that professionals are always there to help you.

The design of the project

If you want a prefabricated pool (kit or shell) or an above-ground model, you can choose between the different manufacturers and find what you are looking for.
In the case of a traditional masonry project, it is advisable to get involved in the design of the pool. You don’t build a pool for just one season, but to enjoy it for a long time and give added value to your home. If you want a pool that is perfectly integrated into the environment, we advise you to opt for a personalised project designed by a professional swimming pool builder.
The pool builder or mason who will build it should submit a dimensioned general drawing with a sketch; in short, something that gives you a good idea of the finished project. This step can take from 1 week to 1 month depending on the case.
Note: This step of the pool construction is very important to serve as evidence in case of dispute about the size or the services provided. You should not be satisfied with approximate estimates without precise and detailed drawings.

The filing of a preliminary declaration
In France, a “Déclaration préalable” or a building permit are necessary; in other countries, no action will be required. You generally get a response in a couple of months. You will therefore have to wait for this period before you can make the first move.
You can, however, take advantage of this period to receive the estimates, study them, compare them and make your decision on the builder. This is also true for those who read our articles but do not live in France and therefore do not have the same administrative obligations.
Here is a reminder of the french regulations.

Building a swimming pool step by step

For an above-ground pool, simply unpack the different elements and follow the assembly instructions. For the others, these are the different steps. For a concrete in-ground swimming pool, depending on the size of the project, the weather or the planning of the companies, the works will last between 2 and 4 months.

The tracing

This is the time to draw your future pond on the ground but also to check that nothing will interfere with the digging. This is a very important step in the building process.
From one or more reference points (corners of the house for example) we draw the points symbolising the location of the pool. For a free-form pool, the triangulation method is generally used.
Caution: when this layout is made, an additional margin on the perimeter must be counted for excavation. It is necessary for the work of the workers who will erect the walls and will serve as a trench for the passage of pipes and ducts. Depending on the construction method, this space must be larger or smaller (20 cm to 1 m).

The earthwork

This step is also called excavation. Depending on the route previously taken, the earth is dug out and then totally or partially evacuated. The depth of the hole must respect the designed profile of the pool.


Its role is to allow water to flow under or around the pool. Depending on the constitution of the ground, a layer of gravel can be provided before the layer of sand and lean concrete. In very special cases (swampy or flood-prone areas) a draining well is necessary.

The structure of the pool

If you’ve chosen a hull, it’s time to have it delivered; for a kit, you’ll have to roll up your sleeves and call friends.
For traditional concrete swimming pools, there are different methods: concrete, renforce concrete, hollows blocks…


steps build pool

The future bottom of your pool is a concrete slab about 20cm thick. The steel bars will be prepared to be connected to the future walls’ structure to give cohesion to the whole structure.

Note that the bottom drain pipe is normally installed in the sand layer before the clean concrete; this is also true for the bottom inlets of an infinity pool.

The walls are built either in a single operation in the case of poured or shotcrete or in several stages if hollow blocks are used. This article explains the self-construction of a swimming pool in hollow blocks. The pipes for the various inlets, skimmers and underwater lights are located at the desired heights.

The pump room

You have the choice: build it at the same time as the pool or use a room nearby. A minimum area of about 2 m2 is required, but this will obviously depend on the size of the pool and the equipment chosen.
Note: there are prefabricated technical rooms to be buried; they are sometimes even pre-equipped.

steps build pool

The hydraulic circuit

At this stage of pool construction, the closed circuit for water circulation must be created. This includes:

  • The connection between the pool and the technical room. For small pools, one pipe is provided for each inlet to be sealed; for large pools, several inlets can be connected together.
  • The equipment in the pump room.

Traditionally for private pools PVC Ø50 or Ø63 are used, depending on the size of the pool.

Note: It is necessary to provide a connection to the main water supply of the house and a connection to the sewage.
A protected power supply must be brought to the pump room. It will be connected to the control panel that protects all the appliances.
Whether it is for hydraulics or electricity, standards do exist and it is necessary to respect them.


After the pipes have been laid and protected in sand, the trench around the swimming pool is filled with a stabilised sand or gravel to prevent any structural move. On the upper part of the backfilling, the earth that has been excavated during the excavation can be used.

Coping stones and pool lining

The coping stones surround the pool walls and must be non-slip. They are laid with a slope towards the outside to prevent the terrace cleaning water from polluting the pool.
For the interior lining, you will have to choose between tiling, liner, reinforced membrane (PVC), silico-marble coating, glass-fibre reinforced polyester, etc. Read this article before choosing the finishing coat for your pool, as some of them are more or less applicable depending on the way you have built your pool structure.

The finishes and the surrounds

Land reclamation: This is a step that many people forget. Removing rubble, cleaning up the site and regrowing vegetation can take time. It is advisable to do the essential work before filling the pool so as not to risk polluting it too much.

Filling the pool

After days, even months, of waiting, you are finally ready for the plunge. Ask the builder or the workers who took care of each step of the construction of your pool to be present; for the necessary explanations, but also to fix any incidents (sticking a pipe badly or not done, for example).

Total duration of the work

Below is the approximative duration of each phase of the construction of an underground swimming pool:

  • Conception: about 1 month. Take time to think about your project
  • Administrative delay: 1 month minimum if the file is complete. Finding workers and buying equipment.
  • Construction: on average 3 months.

Taking the shortest possible time frame, we arrive at an overall duration of about 5 to 6 months. Obviously, depending on various factors including administrative delays and problems encountered during the construction phases, this can sometimes go up to 9 months. You may think, that for bathing at the beginning of June, you can start the work at the beginning of February. In theory you are right, but that is without taking into account the weather variations and the fact that everyone often thinks like this too, meaning there is often a shortage of workers.

The optimal schedule

The design can be done at any time, but it is advisable to choose a moment when you have some free time.
The administrative steps can be done at any time but take into account that an incomplete file can delay the entire process; estimates can be negotiated during this period.
The best time for digging is in autumn; the ground is not frozen even in the coldest regions.
Construction can be done during the winter and finishing can be done during the spring. Your pool will be ready as soon as the first fine days arrive.

Conclusion: our advice

For each step of pool building, there are more favourable times; taking them into account can save you time and money.

  • In the fall and winter, building professionals are not overworked and have a business to run. So take advantage of it. Plus, you won’t be in a hurry, so you’ll take the time to negotiate and get the best deal for your business. Your swimming pool will be ready to enjoy it as soon as the first days of summer arrive.
  • Those who have chosen to build in 2 phases will also be able to spread their budget: the structural work in the autumn and the filtration and finishings in the spring. You will then receive your pool in good condition, without suffering the stress of your children who want to, finally, be able to enjoy the pool, invite friends, etc..

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