Reparing Your Pool For the Summer

Repairing your pool for summer

There is lots of information available for keeping your pool water in tiptop condition, but if you are emptying your pool, it is an ideal time to carry out essential maintenance to the structure, tiling and pipework etc.
There are a number of different types of pool, for the purpose of repairs we will focus on the most common type of built pools (‘de obra’) i.e. of block and normally steel reinforced concrete construction. (many water deposits which are often later used as pools are built in the same way).
Most built pools are either lined with ceramic tiles, or painted with a special pool paint. While some tile replacement can be carried out underwater using special materials (see below), most repairs are best carried out with the pool empty. Pools should never be emptied or filled too quickly as the structure will move due to the significant changes in pressure, (an average sized pool contains around 70 metric tonnes of water). Allow 48 hrs + for both filling and emptying, and avoid leaving the pool without water for long periods.
Once empty, first carry out some checks to decide on maintenance needed.
You will probably be surprised by the depth of your pool when empty as it appears more shallow when full of water. Empty pools are just as dangerous as full ones. Protect them from children and try not to fall in.

 

Main Checks

-         Remove loose tiles to allow substrate to dry.
-         Tap all fixed tiles with a coin to establish if they are still well keyed. You will quickly note the difference in tap tone, between a well fixed tile, and one that has lost most of the key, such that it is likely to come loose soon. Also remove these poorly keyed tiles.
-         Check tile grout to see that it is in good condition. Overtime the grout between tiles will erode and need renewing.
-         Check your bottom outlet (‘sumidero’) to see that it is well sealed to the pool base. Older types (metal or cement) are best replaced with plastic, especially if they connect to old iron pipework. As pipework is normally set in the strong reinforced concrete structure, it is usually more practical to run a new PVC pipe (of smaller bore) within the older iron pipe, effectively using the iron pipe that goes through the pool wall as a duct. Many pool leaks are due to failed pipework and outlet seals, rather than the structure itself, so make sure the condition of all pipes and seals are checked properly before you assume the pool itself is leaking. Also remove jet heads and check that the junction with the pool wall is well sealed. Skimmers can also leak and may need re-sealing. Fortunately the water pressure at jet and skimmer level is so low that slight leaks might be tolerated. It is the ‘sumidero’ bottom outlet and lower pipework that will result in fast water loss if leaking.
-         If you suspect your pool is leaking, all tiles may need to be removed to establish the location of the leak (painted pools will probably make crack identification easy), while a spot repair may be possible (see below), it may be necessary to re-make  the pool structure e.g. with reinforced ‘Gunite’ (‘Gunita’ in Spanish) or a tanking render or slurry coat (see below). The guniting is best carried out by a specialist company and will be costly, because effectively it involves remaking a pool within a pool. If your pool is above ground you may be able to see the location of a leak (often evident with green algae or lichen growth on the outer wall), but water sources can be very difficult to locate and water may have tracked from a failed area of the concrete structure to a different area of the block surround before emerging, so make sure you inspect the pool thoroughly. If you don’t want to remove tiles, you might consider adding a liner. (A specialist company can normally line a built pool with a plastic liner as used for example in timber or steel framed pools, (liners are available in tiled effects too). It may be necessary to level the pool base with sand to incorporate some liner types).
-         Major cracks or very sudden water loss, may result from more serious structural failure e.g. where steel reinforcement has corroded and failed due to poor original construction. Inadequate covering of the steel with concrete and the wrong concrete mix can allow the pool water (and even ground water), to gradually corrode the steel reinforcement, which is essential for strength. Even if the pool is not leaking, evidence of significant cracking or structural movement should be investigated before further use, as pool failure can be sudden and very dangerous especially if the pool is located on a slope or set entirely above ground. Though a well built pool will tolerate some substrate movement, many pools crack when shrinkable substrates contract in very dry weather (2006 was particularly dry), heavy rain can also wash away substrates on steep slopes. Unfortunately excessive movement may well require rebuilding of the pool, but minor seasonal movement (usually only causing hairline cracking) can normally be repaired provided that flexible products area used.
-         Get an electrician to check the seals / bulbs on pool lights. Never turn these on when the pool is empty as the high temperature can cause them to explode!


Materials to use:-

Spot tile replacement


Firstly, yes! there is a material available which let’s you stick tiles back in place under water. It’s called ‘Sika Multikit’ and can be purchased or ordered from most builders merchants that stock Sika products (a similar two part epoxy product called ‘Tufmix’ can also be used. Only carry out submerged work if it is close to the surface (i.e. you can reach it by hand), otherwise employ a qualified scuba diver . In all cases make sure you or the repairer do not work alone. It’s also sometimes possible to add some of the  resin to the back of the tile then carefully push it into place with a long pole, but you will need to apply adequate pressure from above to make sure it beds down. Even if you do opt for tile replacement without emptying the pool, you won’t be able to grout around the tile and other tiles may soon come loose, so inspection and works free of water are normally the preferred option.
When water is not present and the substrate has been allowed to dry, tiles can be re-fixed using a pistol applied adhesive like Sika Bond T2 (apply as a zig-zag line then press into place), this allows for a very thin adhesive layer such that the tile should not stick out significantly above others. Otherwise use ‘weber.col plus’. ‘weber.col dur’ as a tile grout though you will have to be sparing if you want the reaffixed tile to remain level with surrounding tiles.

Tile re-grouting


The grout used for tile joints is often not the same as the sub grout (though weber.col plus is used for both fixing and jointing). To re-grout a pool, firstly clean the pool with ‘Picinet’, applied via a pressurised spray. Gloves, mask and protective clothing  should be worn and manufacturer’s safety precautions followed as the chemical vapour can build up in the pool area, plus the product burns. After ten minutes this can be hosed or power washed away with clean water, which will normally reveal super clean tiles and tile joints.
Once dry the pool can be re-grouted using ‘weber.col plus’ or ‘weber.color premium’. There are 16 types of weber.col grouts so don’t be fobbed off at the builder’s merchant with the wrong one. These two are both resistant to pool chemicals and specifically designed for use in pools.

 

Sealing outlets


All new PVC outlets should first be ‘keyed’ and sand ‘blinded’ before installation, to ensure that a watertight bond between plastic and cement is achieved. To do this the plastic surfaces which will be in contact with the cement surround should be painted with plumbers PVC ‘cola’, and the painted surface should be sprinkled with sharp builders sand while still wet, then left to fully dry. The cola will melt the PVC slightly and the sand will create a rough surface for the cement to key to.
Use Sika Monotop or equivalent ‘mortero impermeabilizante’ to bed in new outlets and seal around pipes etc. This is a quick drying water proof mortar which normally only needs water adding (it looks like plain cement, but don’t add sand). Otherwise use a strong cement/sand, mortar mix incorporating ‘Sikacim impermeabilizante’ (mixed with water!). In both cases, use a relatively wet mix to ensure that the outlet is well sealed and all air tracts / voids are eliminated. Allow at least 10mm of space between the finished cement and the tile base level, so that a secondary waterproof layer of  ‘weber.col dur’ or ‘weber.col plus’ tile grout can be included, then tile round the outlet and re-grout with ‘weber.color premium’

 


Repairing structural cracks and isolated leaks
Complete re-tanking is likely to be far more successful and long lasting than spot repairs, but as a cost effective option spot repairs might be attempted first.
Tap the entire surface with a coin to locate areas of render that have lost their key (normally present around evident cracks). Remove these entire areas, ready for repair.
Grind out cracks in a dovetail form (to 1 cm depth) and deep fill with ‘Sikaflex-11FC’. Larger fissures can be stopped with ‘weber.tec imperstop’ however this will not flex sufficiently under structural movement. Potentially large cracks e.g. up to 2mm can be ground out (1cm deep x 2cm wide) and a movement strip can be bedded into ‘Sikaflex 11FC’, BUT excessive movement will normally result in the tanking layer failing such that larger cracks in pools may well require the Gunite ‘pool within a pool solution’, or a liner.


Following crack repair, skim coat wall surfaces (ideally to a minimum of 1m either side of the cracks) with ‘weber.tec imperflex’ (see below), applied according to manufacturer’s instructions, and retile over using  ‘weber.col plus’ grout and jointing compound. As an added measure, a continuous glass fibre mesh of ‘Sika Armatex 99 (antialcalina)’ can be incorporated between the ‘imperflex’ layers.


For mechanical damage, treat any exposed steel reinforcement with ‘weber FR’ then use ‘weber.tec imperstop’ to repair cracks or holes in the concrete structure. This can also be used on the outside wall of the pool to stop an active i.e. wet leak, without emptying the pool, but bear in mind, ultimately the leak must be stopped from within the pool to prevent long term damage to the structure. Traditionally pools were tanked and re-tanked with a waterproof render e.g. ‘weber.tec imper G’ or slurry coat (brush on) mortar mix e.g. ‘weber.tec imper f’. If the structure is completely free of movement, these finishes can be tiled over, and the pool ‘should’ be water tight, however, as many leaks are due to fine cracks in the structure (which these products won’t cope with), Weber now manufacturer a flexible slurry coat mortar called ‘weber.tec imperflex’. Sika have also released a similar product last year called ‘Sika Monotop 107 Seal’.
The ‘Imperflex’ product can be brush or float applied ( normally in two coats on min 1mm and allowing 4 hrs drying between each coat), but it is reliant on a relatively smooth underlying surface which should be free of any pool paints, such that sand blasting of the surface may be required, or even re-rendering with ‘weber.tec imper G’ first before finishing with the flexible ‘imperflex’. It is recommended that a glass fibre antialcaline reinforcement mesh ‘Sika Armatex 99’  is also  incorporated into the tanking (e.g. between trowel coats of the ‘imperflex’). Once dry (4 days), the new surface can be tiled over using ‘weber.col plus’ or ‘weber color premium’ or painted (see below). If the pool has 90 degree corners, these can be softened into a curve with a ‘weber hormirep’ angle fillet (which will also make cleaning easier).

 


Repainting


If your pool is paint finish only, use two coats of ‘Sika guard Piscinas’ or other high quality pool paint or similar to repaint. (The first coat should be watered down 25%) Older paints should be sand blasted off prior to application and re-tanking with the ‘imperflex’ product detailed above.
Allow all materials to dry (3 days). Before slowly refilling (see below).


Avoid the pool being empty as much as possible, by planning the work well ahead. Ideally as soon as the pool is empty, clean and commence work such that everything is completed in under a week. Avoid works in very cold or very hot periods, which can cause further loss of tile key and shrinkage cracking. Fill the pool slowly (min 48hrs) starting with a hose at the bottom of the pool (initial water splash can cause tile key loss). Make sure any work related dust, grout etc is sent to ‘waste’ before putting the filter in operation.



If in doubt consult a pool installer, Gunita contractor or pool lining specialist to a carry out all repair works.
Regular checks and maintenance when your pool is free of water, will normally help to ensure a very long life for the all important steel reinforced structure of your pool. Leaks are best stopped soon after they occur. People new to pool ownership should remember that the pool water level will go down due to evaporation in the dryer hotter months. So what appears to be a very slow leak is not always the case.

NB:- Information for advice purposes only. Proper safety precautions should be taken  and legal procedures followed when carrying out all works.

Information provided by Mark Paddon BSc Hons Building Surveying. MCIOB. Structural Surveys in the Valencia – Alicante . www.surveysspain.com  T: 962807247 M: 653733066 . Free 17 page  property buyer’s guide and advice available via e-mail request to This email address is being protected from spambots. You need JavaScript enabled to view it.

ã Mark Paddon 2008
If your pool is paint finish only, use two coats of pool paint or similar to repaint. (The first coat should be watered down 25%) Older paints should be sand blasted off prior to application and re-tanking with the product detailed above.Allow all materials to dry (3 days). Before slowly refilling (see below).
If your pool is paint finish only, use two coats of pool paint or similar to repaint. (The first coat should be watered down 25%) Older paints should be sand blasted off prior to application and re-tanking with the product detailed above.Allow all materials to dry (3 days). Before slowly refilling (see below).

Complete re-tanking is likely to be far more successful and long lasting than spot repairs, but as a cost effective option spot repairs might be attempted first.Tap the entire surface with a coin to locate areas of render that have lost their key (normally present around evident cracks). Remove these entire areas, ready for repair.Grind out cracks in a dovetail form (to 1 cm depth) and deep fill with Larger fissures can be stopped with however this will not flex sufficiently under structural movement.Potentially large cracks e.g. up to 2mm can be ground out (1cm deep x 2cm wide) and a movement strip can be bedded into , excessive movement will normally result in the tanking layer failing such that larger cracks in pools may well require the Gunite ‘pool within a pool solution’, or a liner.

Additional information