Vinyl Liner Swimming Pools

The invention of the vinyl liner has been the most significant thing that has ever happened in the swimming pool construction industry

And they are now used all over the world and there is a seeming unlimited number of colour and pattern varieties available.

endless variety of patterns

Liners are now produced that are suitable for every type of pool - from the heaviest used commercial pools - to the pools with the highest environmental loading from ice, snow and the sun.

In any climate where there are quite high extremes of temperature varying between about 30 degrees C in the summer down to several degrees of frost in the winter – a vinyl liner pool will last longer and maintain a better appearance for longer than a than a tiled Shotcrete pool.

That is the primary reason why all outdoor pools in Northern Europe and the North Eastern area of the US are vinyl liner pools.

In short PVC liners are generally seen to be “The best thing since sliced bread in a hostile pool climate like the UK's ”!

And there is no doubt that the best way to renovate an old concrete pool is to install a new vinyl liner inside the old pool !

vinyl liner being installed

The history of swimming pool construction

The history of swimming pool construction can be divided into two distinct eras - Before PVC Liners and After PVC Liners.

Before Vinyl Liners

Before Vinyl Liners there were only two methods that the best professional pool builders could use to construct swimming pools.

The first method required the construction of a very heavy thick highly reinforced concrete tank using conventional concrete. The tank was designed and built in accordance with same standards that the sewage and water industry used for their sewage works and water tanks.

The walls and floors were very thick, heavily reinforced and very expensive. The swimming pool builders predominantly used heavy metal or timber forms that the concrete was poured into to form the walls. The work required a large highly skilled labour force and a lot of concrete and reinforcement.

The second method required the construction of a thinner reinforced concrete tank using very high strength "Gunite" dry concrete that the swimming pool contractor sprayed onto formwork using high pressure compressed air.

This has now evolved into the common Shotcrete process that we describe elsewhere on this website.

After Vinyl Liners were developed

The introduction of PVC vinyl liners by a German company allowed swimming pool contractors to develop pools that were not as rigid, stiff and costly as the concrete tank type pools where the actual structure had to be designed to hold water.


The structure of a PVC Liner pool has to be stable enough to be certain that structural failure will not occur but not totally rigid like the structures required for tiled swimming pools. This is because minor structural movement does not lead to leaks because the water proofing is provided by the PVC Liner.

Do Not Use Panel Pool Kits for Pool Walls!

It is unfortunate that various panel product manufacturers have jumped onto the pool construction bandwagon and have produced a wide array of panel pool kits that are entirely unsuitable for buried in-ground pools where they are now frequently used.

One of the largest UK pool companies has carried out a superb marketing campaign selling the panels that are based on the technology that was originally designed for cold store construction as swimming pool kits. DRUMBEAT …........... THE ONLY INSULATED POOLS ON THE MARKET!!!

These are very expensive, are not particularly easy to build and in the view of Will Witt are a load of f.......... rubbish – and yes he has built two pools using these kits so he does have direct experience of them.

The reason is quite simple – the pool walls are retaining walls and even if the plastic/wood/thin steel panels can hold the retained wet earth back when the pool is full of water that is pressing the panels against the earth - the minute the pool is emptied the walls are likely to collapse. Any build up of groundwater in the subsoil around the pool will only make this condition much worse.

You cannot empty a panel wall pool - because the walls are likely to collapse

And that is exactly what happens – if you read the small print in the pool wall kit contract it says just that – DO NOT EMPTY THE POOL.

Will Witt is a professional civil engineer with 40 years experience and he says quite categorically that pool wall kits are a scam that should be avoided by every pool buyer.

Every pool will need to be emptied from time to time to clean it, change the water etc. – pools that cannot be emptied are useless.

You will probably only need to empty your pool in the spring - when it is most likely to collapse

When are you most likely to want to empty your swimming pool? - in the spring when your water has gone green during the winter. And when is the groundwater likely to be highest around your pool? - in the spring of course!

And these pools are also the type that is most likely to be damaged by ice in the winter.

In very cold winters the only way to stop ice pressure from knackering the pool is to break the ice up and empty the pool – this is a bit difficult if the walls are likely to collapse when you do so!!!

Concrete Block Pool Vinyl Liner Walls

When vinyl liners were first introduced into swimming pool construction concrete block walls were used to form the pool walls. The sequence of construction was as follows:-

  1. Excavate pool

  2. Cast reinforced concrete slab on the base of the pool

  3. Build the pool walls in hollow concrete blocks with reinforcement in the wall and fill the voids in the wall blocks with structural concrete

  4. Render the walls

  5. Fix the liner lock on the top of the wall

  6. Install the liner

This method is still employed by many artisans in France as well as the UK and the US to build pools and can be carried out on a DIY basis.

Sometimes lightweight concrete blocks are used and reinforced them with solid reinforced concrete columns and beams within the thickness of the wall itself.

The main drawbacks to this system are that:-

Polystyrene block reinforced concrete pool walls are stronger and much easier and faster to build and provide a better finish for the vinyl liner to rest against. Bluepools owns the brand "PolyBlok" and supplies the kits for the construction of this type of pool when they are best suited for the needs of the Client.

PolyBlok Pool Walls

The polystyrene blocks look like this:-

Please click on the thumbnails below if you would like to see a much bigger picture.

Polyblok pools with vinyl liners have the following advantages:-

If they are not abused they never ever leak

The Flexibility to provide every shape or depth

Insulation against Heat Loss

Much Lower Installation Cost than a Tiled Pool

Lower Running Costs and more comfortable water temperatures

Very high structual strength and the ability to resist Ice Loading and Earthquakes

Low Maintenance Costs

Easy Renewability by liner renewal at a fraction of the cost of re-tiling

Cleaning Ease avoiding permanent scum lines on the tiling

Resistance to Hard Water and avoidance of limescale on the tiling

Comfort and Safety in Use from the soft clean underfelted vinyl liner on the pool floor

So a vinyl liner polyblok pool is probably the best solution for a DIY swimming pool – they are easy to build and are the best type of vinyl liner structural options.

The polyblok on the left is a standard block and the one on the right is a special block for the pool corners. They can be cut to length so that they bond like bricks in a matter of seconds - so the whole pool wall structure takes about an hour or so to carry the blocks into the pool site and then put them in place in the pool wall.

You can see the small lugs on each side of the block cross pieces that carry the 2 horizontal 8mm high yield steel reinforcing bars and in each of the 4 vertical cells of the block there is a similar bar that connects all the layers together and ties them down to the 500 mm wide 150mm thick high strength concrete foundation.

All that needs to be done then is to fill them up with concrete and backfill around the pool.

They work like this:-

polyblok wall sketch

PolybLoK Pool Installation Sequence

  1. Excavate for the pool

  2. Cast concrete wall foundation and install high yield vertical reinforcing bars

  3. Lock polystyrene blocks into place

  4. Fill them with high strength concrete

  5. Insert high yield steel connection bars through polystytrene into the wet concrete

  6. When the concrete has hardened remove outer polystyrene layer over 150 mm depth

  7. Place filling between wall and excavation

  8. Cast ARconWall slabs that resist Ice Loading and anchor the walls when pool has to be emptied

  9. Cast levelling concrete on pool floor

  10. Screed the floor of the pool

  11. Glue underfelt to walls and install pool liner

  12. Fill pool, install pool plant and commission the pool filtration equipment

  13. Landscape the levels to the ground around the pool

The Steel Reinforcement in the walls makes these pools the strongest and most durable available for liner pool installation

The connection bars (no 5 in the sketch) are pushed through the polystyrene into the wet concrete of the top block after concreting of that section of the wall has finished.

There is no stronger, quicker or easier way to build a very high strength earthquake-proof swimming pool that also has insulated walls. There is no better way of building an insulated in-ground swimming pool that will resist ice pressures and allow the pool to be emptied at any time of the year without any risk of wall collapse.

The only other in-ground pool on the market that is as strong as these pools are Shotcrete pools.


The Bluepools System

Bluepools has developed and refined the design of a horizontal reinforced concrete slab element that is connected to the top of the insulated reinforced concrete walls and spans from the top of the insulated wall to the undisturbed ground that surrounds the pool excavation.

These slabs both support the paving that is laid around the pool so that it does not settle and also support the tops of the walls against ice expansion pressure in the winter.

Most importantly they also prop and hold the tops of the swimming pool walls so that a PolyBloK pool can be emptied at any time without any risk of wall collapse.

These slabs are always reinforced with steel mesh wire high yield reinforcement and are always built in a continuous ring beam all around the pool perimeter so that the pool walls cannot be pushed outwards by ice loading in the winter or inwards by earth pressure when the pool is empty,




Liner Types

Spray Applied Membrane

FTS manufactured by FTS-Aquatics

As with any product containing a pigment, over time colour will fade. However, with a Certi-Skin FTS Polyseal 25 membrane, the core of the product as a tough membrane will still be sound, therefore it is a simple process to apply a thin re-fresh coat over the membrane to make it look as good as new – no need to re-line the pool.

Integrity Test

After the spray application, but before the final UV protective finish, the whole pool undergoes a ‘spark test’ which electronically identifies any potential weak areas so they can be rectified there and then so that the Certikin team are 100% confident on leaving site that the product lives up to it 25year guarantee.

Product Features

Will Witt Comments

I have never used FTS Polyseal 25 – but it looks like the best thing since sliced bread for pool renovation and it it comes with a 25 Year guarantee from Certikin there is very little risk of it going wrong

On-Site liners for Commercial Pools and Infinity Edge Pools


For a durable, good looking pool finish, look no further than Certikin On-Site Lining. Suitable for new and refurbished, domestic and commercial pools, our on-site lining products are tough and durable and are specifically designed to improve a pools performance for many years.

Available in a range of traditional and modern patterns and in plain and anti-slip finishes with colour co-ordinated liquid PVC to seal the welded seams, AGAM PVC is produced to a 1.5mm thickness and includes a reinforced polyester mesh to offer strength with flexibility. The PVC can be applied to almost any existing pool finish, either directly or preferably over a geo-textile underlay which will further enhance the feel of the PVC and assist it in reducing thermal conduction.


Installation is undertaken by Certikin's own contractors and every care is taken to ensure that a smooth and professional job is completed. The 50mm overlapped welded seams are spike tested for adhesion before being sealed and all the appropriate perimeter anchor points are made with stainless steel expansion drive rivets. The PVC is cut, tailored and welded on site to ensure an accurate and neat fit to the pool whilst allowing for the slight movements in the pool structure that can occur.

All plain colours (including white) are available in standard or anti slip and with colour co-ordinating liquid PVC to seal joints.

Thin Liners for Domestic Pools

Certikin offers the widest choice of colours and patterns …..

….....from the world’s leading vinyl manufacturers, combined with the highest quality manufacturing techniques. Certikin swimming pool liners are one of the best possible option to bring your pool to life.

With a pattern and colour range which continues to provide the traditional options but also challenge the ‘norm’, Certikin offer a wider choice than ever before to liven up almost any pool.

In-house state of the art design and cutting procedures ensure even the most complex shapes and sizes can be re-created. Their pool vinyls are sourced from the world’s leading vinyl manufacturers: Canadian General Tower; Elbtal Plastics and Renolit, all of whom create materials to exacting standards and have a combined manufacturing experience of over 160 years.

This range of supply allows Certikin to have the widest choice of patterns and colours available in the UK market, including many exclusive designs, without compromising quality.

Modern design and manufacture techniques allow us to take these excellent materials and create a high quality liner for almost any size or shape of pool, including those with features such as ledges, freeform curves, cover pits and integral steps.

As such, all of the liners Certikin manufacture, offer the following qualities and features:

It should be noted that, despite best efforts and best practice during manufacture and despite use of the finest raw materials that some restrictions apply and/or the following effects may be visible and are in no way classed as faults.

Patterns on printed floor and wall panels and on tile bands, including mosaics, may not match at the seams due to high stretch factors, pattern complexity and cutting techniques – aesthetic quality is not regarded as a warranty issue – pool owners should be aware of this when choosing a liner pattern.

• Many darker materials are printed on lighter backgrounds. It is therefore common to have a fine light-coloured line along each seam due to the flow of material as it fuses together – this is the mark of a solid weld and is not a fault.