6.0 SUB-CONTRACTING or OUT-SOURCING SECTIONS OF WORK

6.1 LAYOUT & POSITION

This work can be done by a surveyor so that the end result is correct & perfect, a surveyor can also establish if you are the correct distance from the boundary & also if the boundary adjacent to your pool is in the correct position. Many times pools have been built after measuring from a boundary only to find the boundary was incorrect & now your pool is partly in next doors yard.

6.2 EXCAVATION

This work is normally done by a sub contractor weather the pool is built by a pool builder or an owner, most pool builders use companies who specalise in digging pools.

If you are building the pool yourself, then you can call around to a number of excavation companies & have them come & see your area & the pool design & give you a quote.

Make sure to include the removal of the soil from site & costs to dump the soil as well ask them for a cost for rock dig incase you hit rock. This will normally be quoted per Cubic metre for rock dig.

Make sure that they are insured, in case they accidently knock down a part of your house when entering or exiting the property or when digging.

Make sure they are given written instructions on which trees & garden is to be removed & which is not & supervise them if possbile.

6.3 FITTING INCORPORATED ITEMS:

There are many pool service companies who will also provide the service of supplying & fitting the skimmer box, returns, lights & any accessories in to the pool prior to concreting.

You can also buy all the components yourself & then have a pool service company just do the installation.

The pipework connections to these components need only protrude in to the soil behind the concrete area at this stage. If the area is not accessable then the pipes will have to be installed & run to the area for the pump & filter.

You must do the connection from the main drain in the base of the pool to the skimmer box before setting the steel.

Make sure to read all the detail in the Construction section in fitting incorporated items before proceed in here.

6.4 FORMWORK & STEEL FIXING

These two trades normally go together, There are many steel fixers who dont know how to do pool steel, preferably use a subcontractor who does pool steel as a normal work proceedure as they know how to do it quickly & efficently. They will normally set up the top edge form to get the outside edge of the pool & the set the steel accordingly. You can purchase the steel yourself but remember to also buy the tie wire & bar chairs The steel fixers will normally supply the form work & labour only.

PROTECTION:
It is always necessary to protect any buildings, gardens, fences & adjoining property from the possibility of being coated with concrete shoul there be a problem during spraying. It is not normally a big problem but dont take any chances, there can always be a blowout of a nozzle or a blockage in one of the pipes. Dont take any chances cover everything you can.

CUT LINES:
If the pool has any straight sides, you will be able to set up lines using piano wire or fishing line. These will be set 150mm or 6" inside the dig line or as specified by the engineer.
These lines help the concrete sprayer & cutter to provide a straight wall for you.

6.5 CONCRETE SPRAY:

This is a specialist job and there are always concrete spray pump companies advertising in the yellow pages.

The job of the concrete sprayer is to pump the concrete supplied by the concrete company & place it on the interior of the excavation to the dimentions of the drawings & he will have men who will cut or finish the coincrete to the exact shape ready to recieve the specified finish.

The concrete sprayer will give a price in two ways,
1. Spray & cut only or
2. supply concrete & spray & cut.

The concrete sprayer will be happy to include the supply of concrete in his fee if he has a contract rate with the concrete supplier or if he thinks that there will be a good lot of concrete used or if he thinks he can get away with the least amount of concrete.

I would advise that you should contract with the concrete company directly yourself to supply the spray mix concrete. There will need to be certain criteria which will need to be specified to both the supplier & the concrete sprayer.

Price
Always negoiate a price with the supplier prior to delivery. Remember that the concrete company may charge waiting time while the truck is unloading. (It normally takes longer to unload a truck when spraying versus when the concrete is being pumped through a 4" hose for a slab.

Time -
For the benifit of the concrete pump people, you will need to nominate a time for delivery but it is best to advise that they dont batch untill you call to confirm. You usually do this when the concrete pump arrives on site & the concrete sprayers say they will be ready in "X" minutes.

Volume:
The volume of concrete used on a pool varies dependent upon the trueness of the cut or formwork of the pool. If the pool was perfectly rectangular & had an even fall from the shallow to deep end & you had excately 150mm (6") of concrete then it is easy to calculate the volume required. With a freeform pool it is not quite so easy. The easiest way to get a good estimate is:
Measure from the top of the pool down the wall to the middle of the floor at three points. Take an average of that figure & multiply it by the distance around the top edge of the pool.

If the engineer has specified 150mm (6") thick then multiply the area from your first calculation by the thickness of the concrete

It will look something like this
Top of wall to center average 3.6M or (12 Ft)
Distance around top of pool 35M or (115.5 Ft)
3.6 x 35 = 126 SqM or 12 x 115.5 = 1386 SqFt
Concrete thickness specified by engineer 150mm (6")
Volume = 126 x .150 = 18.9 Cubic Metres
Volume = 1386 x .5 = 693 Cub Ft or 25.66 Cubic yards.

You will then add on another 2.5% for the beam around the top of the pool if it is a normal 300mm or(1.0Ft) wide & 200mm or (8") deep.
18.9 + 2.5% = 19.37 or 20 Cubic Metres 25.66 + 2.5% = 26.30 or 27 Cubic Yards

You will give this amount to the concrete company & they will supply that amount to the last truck & then ask for confirmation of what is required to finish.

Concrete Mix
- The engineer should nominate a concrete mix relative to the standard for the authority under who you are building. Some times this mix design must be changed due to site circumstances so please be sure to pass on to the concrete company the engineers request.

Left over
- It is always a problem to get rid of any left over concrete even if it is only a few cubic feet. Make sure you have a slab prepared for where the pump & filter & heater are going to sit, you can always use any left over concrete to construct this pad.

Cleanup
- Most Counties & Councils now require that there is no concrete washed down the drains when the concrete trucks & concrete pumps wash up.
Have someone checking all the time to make sure that any spilt concrete on the road or footpath is cleaned up & not washed down the drain. If you are building the pool yourself then you are responsible for the containment of waste.

Thickness Testing -
During spraying, the operators of the spray gun are experienced in the application of the concrete & will endeavour to place the required thickness on to the surface.
If the sprayer is also supplying the concrete, they may try to use the least possible by only just getting to the required thickness & if you are supplying, they may tend to go thicker than really required so keep an eye on it.

Slump Testing
When you order the concrete the sprayers will advise what slump they want to best suit their machine & the surface they are spraying on to.
Normally they will want a 65mm or 2.5" slump which is dry enough to hold up well but wet enough to pump through the small spray hose. Make it a requirement that the concrete supplier slump tests each truck & notes the figure prior to the truck dispatching its concrete.

Concrete Testing
You will also need to request that the concrete company or an independent testing company take two test cylinders from each truck of concrete & supply you with the results after 7 days & 28 days. This will provide the engineer with proof that the concrete has been supplied as specified.

Curing Of the Pool Shell Concrete:
The most important part of constructing a concrete swimming pool is correct curing of the concrete.

There are many different ways which are used, such as spraying the concrete three times a day or all day with a garden hose or sprinkler or putting hesian bags over the concrete & wetting that three times a day.

I have found all these work to an extent but produce different results in different climates.

The only process which I know to work in all climates & I have used it from Hot Dry Desert areas to Below Zero areas & in Tropical area.

PLASTIC ENVELOPE THE POOL.

This is no more costly & less time consuming than the spraying of water or use of hesian bags.
Simply use sheets of thin black plastic laid over the entire pool so it sits against the surface of walls & floor & then it up over the top & seal it around the edge with soil. You must use tape to seal all the joins in the plastic.

This system will allow the concrete to cure in its own juice. As long as the air cannot get to the surface, the concrete will sweat & continue to cure for the seven - fourteen days that the plastic is left on. Even in below zero temperatures, the concrete will develope high temperatures below the plastic.

I have never had a problem with any sort of cracking when using this method.

Dont use any extra water as it may cause cracking in cold climates or evaporate off in hot climates thus reducting the temperature of the concrete.

6.6 SECONDARY PIPEWORK:

At this stage while you are waiting for the concrete to cure, you can finish the pipework connections between the pool & the area where the pump & filter are to sit.

Remember that in most places there is a regulation as to how close the pump & any other high voltage electrical equipment can sit from the pool In Australia it is 3.0M 10ft unless there is a minimum 1.2M high wall between.

Also remember to select an area for the pump & filter which is easy access but not unsightly & that the small noise from the pump will not annoy neighbours.

Remember the most important rules about running the pipes to the pump & filter area.

SUCTION PIPE FROM SKIMMER TO PUMP

• Never raise the pipe above water level when on the horizontal.
• Never raise the pipe up & then down again before the final rise to the pump.
• If the pump is more than 500mm or 20" above the pool water level, then install a non return valve in the line as close to the pool as possible. This may mean having an inspection box beside the pool to allow future maintenance.
• If you install a non return valve always put a union each side of it so it can be removed for service.
• Never reduce this line in the horizontal plane, always wait untill the final riser before the pump & reduce if needed on the vertical.
• If your pump & filter are below water level, then install an ON/OFF plastic ball valve in this line to allow you to shut off when cleaning the strainer in front of the pump.

RETURN PIPES TO POOL

• If the pool is below water level then install a check valve in this line after the last accessory, eg heater or chlorinator.
• If you are using more than a 3/4 HP pump, then use 50mm or 2" pipe as a main run to the pool & then split in to 40mm or 11/2" for the various returns.
• Make sure the tees you use to split the pipe to the returns are the size of the main return line & then reduce size on the branch, not on the main line.
• Make sure to allow for the connection of any accessories that may come after the filter.
• If you have a heater in the system, make sure to put a loop in the pipe higher than the heater before dropping in to the ground & back to the pool.

6.7 POOL INTERNAL FINISH

You need to be careful here with sequencing the subcontractors for the finishing components. If you have a pool, which has a tile line around the top at water level or you are doing a fully tiled pool, you will need to arrange for the subcontractor to do the plastering for these first & then to apply the water line tile or the first row of the tile if fully tiled.

Again as with the concrete, it is good to cure the plaster for a number of days if you are going to fully tile the pool.
If it is just a water line tile row application then this is normally done the day after the plaster has been applied to provide a flat surface for the tiles.
Unlike a bathroom a pool is tiled from the top down as the tile has to be perfectly level at water line. Therefore it is better to get a pool tiler to do the pool, not a normal house tiler.

Once the top level tile is in place, then the coping can be applied as there is now a level to work to.

You may consider it it is correct to have the tiler finish a fuly tiled pool at this point as the tiles have to be protected when the top surround coping is applied, some times it is better to hold after the first row, then apply the coping & then come back to a clean shell & tile that.

After the coping has been applied, then you can have the rest of the interior finish applied.

If you are having fully tiled, then the subcontractor can go straight on with that. Note be careful to use a good quality cement based tile adhesive, it is not necessary to use an epoxy glue or a modifier with the glue unless you expect to get a lot of ground movement.

If you are having a marcite (marble dust & white cement ) finish, then this should only be applied when all the area around the pool is cleaned & the pump & filter connected & if necessary a safety fence installed as you will have to begin & continue to fill from a few hours after the marcite is applied.

Also if there is any dust blowing around, the applicators can not help but get some of of it into the white finish.

If you are having a pebble interior finish, then this can be applied as soon as the water line tile is finished or if it is to go to the top, then it is applied once the coping is in place.

Finishes such as Fibreglaze have to wait for a 28 day curing period for the plaster before application.

6.8 POOL COPING;

Many pools have a beam 300mm or 1.0Ft wide around the top of the pool which has to be finished before the rest of the interior of the pool is finished. The finishes used are covered in the construction section of this site & can be refered to there. The sub contractor will need to have his water line tiles in place to get a pefect level for the coping.

In many cases the coping & the surround are one piece & this must again be done after the water line tiles & before the completion of the interior.

6.9 ELECTRICAL INSTALLATION

Make sure that al your electrical connection conduits & junction boxes are in place before the interior of the pool & the surround work are finished, this will include the lights, water level controller & air buttons for a spa.

Also try to make sure that you have permenant power to the filter pump so that you do not have to run extension leads.

Be sure to allow for time clocks for the filter pump & pther pumps & also for controlling the lights.

6.10 EQUIPMENT INSTALLATION

It is preferable to have your pool equipment all installed prior to finishing the interior of the pool.

This means:

• Filter Pump
• Filter
• Heater
• Chemical Treatment
• Auto Pool Cleaner Boost Pump if needed
• Spa Boost Pump if Incorporated

It is much easier to be able to start the equipment as soon as you have the pool full.

6.11 POOL SURROUND

Another item to work on while the pool concrete is curing is the deck area around the pool, if this has not been done as part of the pool.

You can set you levels to give fall away from the pool so water does not pool around the pool.
Don't do to much fall towards the house unless you intend to install a gutter or drain off grating between the house concrete & the pool concrete.

There are a number of companies who make concrete joint systems & inserts in to concrete for drainage but one of the best I have found is from MORTEX in Tucon Arizona (Agents in Australia in Perth & Bowral NSW)

Always check these falls before the subcontractor pours the concrete. You will also need to allow for what ever thickness of finish you are applying to the surrounds.

When setting out the surrounds, you can use 1" or 25mm plastic pipe set in the ground to act as a fitting for an unbrella or you may want to incorporate supports for a pagola at a later date.

6.12 COMMISSIONING THE POOL

Once you pool is full of water, you will need to begin adding chemicals to adjust the water balance (see water balance section of Chemical Treatment),

It would be preferable to take a sample of water from you tap to the local pool shop & have them test it prior to filling or while filling to get an idea of the pH, Total Alkalinity & Hardness levels on the water you are using. THis will allow some idea of what & how much chemicals need to be applied during & straight after filling.

When you go to start the pump, you will have to prime it by removing the lid from the strainer in front of the pump & filling this with water, allowing it to run down the suction line to the pool for a minute or two.
You can start the pump once you set the valve on the filter to the "Waste" position so that any rubbish in the line will not be forced in to the filter.
Read the information on the starting & operation of the particular type of filter you have in the "Filters:" section of the swimming pool service section of our web site.

Happy Swimming.

POOL CONSTRUCTION MENU

Preliminaries

Designing the Pool & Surrounds

Hydraulics & Filtration

Accessories

Clearing the Area

Construction Sequence

Subcontracting or Outsourcing

Surround Development

Web Page written by:
Victor K de Fontenay © Jan 1997
Page last updated 4:27 PM on 24th April 1999