CONCRETE SHELL

The shell of a concrete swimming pool, is exactly that. The concrete shape of the pool, with a rough finish before the completion of the tiling, plaster, light and plumbing fittings, headers and water. Depending on your design your shell may have to be built before your home. If a shell is built where structures already exist protective measures may have to be put in place to stop the undermining and damage of these structures. These protective measures will usually only need to occur for structures less than 1m distance from the water line. The most popular methods may include sheet piling, pillars, chemical injection, grouting, and Shotcrete.

There are four stages to building a concrete shell

Excavation – set out plans, dig plans, equipment used, waste removal,
Form work – the datum mark, positioning of plumbing to account for water flow, lighting.
Steel – correct steel, engineering requirements
Concrete -

EXCAVATION

• Where is the datum? (The top of the Pool) – This point should be marked.
• Mark out the area of your pool with string line. Pegs in the ground will be sufficient. If your pool is being built before your house survey marks will be required. Excavation includes the pool area + thickness of concrete + 400mm clearance.
• The depth of your hole is the pool depth + concrete thickness + 50mm (water line) + 60mm (Header thickness) from the datum mark
• Ensure that the walls of the hole do not taper inwards.

FORM WORK

• Mark out the pool with pegs and string line. Include the thickness of the concrete + 30mm (tiles and plaster) + pool dimensions.
• Dig your post into the ground using the string line as your guide. Post should be placed about 400mm from the corners and about 700mm apart along the length of your pool. Use a spirit level to ensure your posts are square.
• Mark the top of the pool shell on all your post using a laser level. The top of the pool shell is the datum – 60mm (thickness of the header). Fasten corrugated sheets using this line as the start. Work your way around the pool until you get to your depth.
• Hammer star pickets into the ground above your pool. (About 1 star picket to every 3 post) Tie 8 gauge wire to the pickets and brace the pool wall, threading the wire between post and corrugated sheets. Back fill wall enough to stop movement. Brace and back fill to ensure the pool walls are straight.
• Cut the post flush with the top of the corrugated sheets.

STEEL

• Place one 100mm bullet head nail on the second corrugation of every post. Using the back end of your hammer bend the top of each of these nails, this will be for the placement of your top starter bar. Place and tie steel onto these nails.
• Use the same procedure to place a bottom starter bar.
• Use a crayon to mark 300mm along the top starter bar.
• Place and Bend steel along these marks tying into top and bottom starter bars. The length of the pool, the width, the walls, then the floor.
• After completion of steel tying, cut wire from top and bottom starter bars, lift steel, place spacers underneath steel and tie back to starter bars.