Waterproofing an in-ground swimming pool: 5 basic tips

In-ground pools are a popular choice for those looking for a durable and customised design option. However, one of the biggest challenges they pose is the waterproofing of the pool shell. If the waterproofing is not done correctly, water leaks and seepage can occur, which can cause costly damage and a decrease in property value. Here are five basic tips for waterproofing an in-ground pool.

In-ground swimming pools: basic characteristics

In-ground swimming pools are predominantly made in three ways: gunite, reinforced concrete or concrete block pools, even more recently with EPS block or mould. Their construction is a complex process that requires the hiring of a specialised builder. They are customisable and can be designed in different shapes and sizes to suit the needs of each home.

In contrast to prefabricated pools, in-ground pools take longer to build and can be more expensive. However, a well-built, well-maintained swimming pool, with the correct waterproofing, can last for decades.

Types of liner for in-ground swimming pools

There are several types of liner that can be used in an in-ground pool, ranging from tiles (Gresite is very popular) to fibreglass liners and special paints. Each type of liner has its own advantages and disadvantages, but tile liner is one of the most popular due to its durability and aesthetics. Fibreglass cladding and special paints are more economical options, but may require more frequent maintenance.

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How to waterproof an in-ground swimming pool: TIPS

Resting of concrete

After the construction of the in-ground pool, it is important to allow adequate time for the concrete/mortar to cure before applying the liner and waterproofing. The curing of the concrete or mortar is crucial to ensure that the pool is completely stable and will not crack or leak in the future. The recommended set time varies depending on climate and other factors, but typically ranges from 28 to 60 days.

Uniform surface (regular)

Once the concrete has cured properly, the pool surface must be prepared for the application of the coating and waterproofing. It is important to ensure that the surface is even and free of imperfections before applying the waterproofing coating. This can be achieved by using a sander or surface grinder to level any bumps or protrusions in the surface. It can also be levelled with a non-structural repair mortar compatible with the concrete substrate.

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Applying quality waterproofing mortars

The choice of waterproofing material is key to ensuring the long-term durability and strength of the pool. Quality waterproofing mortars are specifically designed for use in in-ground pools. It is recommended to choose a superior quality (flexible) waterproofing mortar, as it can guarantee greater resistance to water seepage and leaks, adapting to the small movements produced by the difference in pressure and temperature to which they are subjected.

In this sense, waterproofing mortar is a material used in the construction of swimming pools to ensure watertightness and long-term resistance. Choosing the right waterproofing mortar is crucial to ensure the durability of the pool and the prevention of water seepage problems.

There are different types of waterproofing mortars and it is important to choose one that is suitable for the specific needs of the in-ground pool. Quality waterproofing mortars – such as those offered by Molins – are designed to withstand constant exposure to water, chlorides and pool chemicals and should be applied according to the manufacturer’s instructions.

For example, one of the advantages of using flexible cementitious waterproofing mortars is that they can be applied on different surfaces, such as concrete, cement, brick and other building materials. In addition, they can be used to repair damage to the existing pool, instead of having to replace the entire liner. Another important feature is that this type of waterproofing allows any type of finish to be adhered to it, whether it is a ceramic finish or pool paint.

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It is important to note that the application of the waterproofing mortar must be carried out by a qualified professional to ensure a proper and uniform application. Surface preparation prior to the application of the mortar is also crucial to ensure that the mortar adheres properly and avoids future leakage problems.

Ultimately, choosing the right product is very important to ensure the durability and long-term resistance of the concrete pool. Cementitious flexible waterproofing mortars are specifically designed for use in in-ground swimming pools and must be applied by a qualified professional according to the manufacturer’s instructions. With proper maintenance, the life of an in-ground swimming pool with a quality waterproofing mortar can be extended for many years.

From Molins, we want to advise you through our experts so that you can waterproof a swimming pool with excellent results.

Molins products for waterproofing swimming pools on site

PROPAM® IMPE FLEX

To ensure waterproofing, we present PROPAM® IMPE FLEX for interior and exterior waterproofing of concrete and masonry. Waterproofing above and below the water table. Basements, lift shafts, tunnels, concrete pipes, swimming pools, water tanks, etc.

Flexible waterproof coating on walls and floors of showers, bathrooms and washbasins, prior to ceramic tile installation. Protective coating on concrete repair systems. Indicated and designed for swimming pools (resists chlorides), terraces and balconies and all those applications where strong changes in temperature or pressure occur. Can be used to waterproof cracked walls, resists small movements.

BETOTAPE SEAL

BETOTAPE SEAL elastic band is an indispensable aid in the waterproofing of swimming pools alongside flexible cementitious waterproofing products. It is designed for use in the sealing of expansion joints, half-pieces, cracks and fissures. It is a waterproof thermoplastic elastomer (TPE) with a geotextile on both sides to adhere perfectly with the flexible cementitious waterproofing used.

PROPAM® FLEXITEC

PROPAM® FLEXITEC is a high quality flexible waterproofing mortar. It is specifically designed for the waterproofing of in-ground swimming pools and is composed of a mixture of special cements, selected aggregates and synthetic resins.

For large surfaces, the advantage of being a two-component product is that it is quick to mix, no water is added.

One of the main advantages is its high flexibility, which allows it to adapt to possible movements and settlements of the pool structure without suffering damage or losing its waterproofing capacity. In addition, this mortar is resistant to sulphates and chlorides, which guarantees its durability and quality in the long term.

And it is very easy to apply, both on horizontal and vertical surfaces.

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