How to Build a Concrete Block Swimming Pool
Cement Block Pool Construction
There are several methods for using concrete block in the construction of a swimming pool. The method described in this section will be for building a concrete block pool that can be plastered or used in conjunction with a vinyl liner. to ensure that the pool walls don't separate from the floor, the pool floor will be poured first with the footer incorporated in. This is just one method for building a concrete swimming pool.
- First establish the size of the swimming pool and the location.
- For an 8" block wall pool we want to mark the location 12" larger on all walls.
- Set stakes at the 4 corners of the dig area, cross measure to ensure the dimensions are square.
- Pull string from each of the stakes to mark the outside perimeter of the dig.
- Next, set string to the desired finish grade of the pool and check for level.
- Dig hole just inside the string and stakes
- Depth can checked from the strings. add for 6" concrete in the floor 3" for water line and the thickness of coping to be used to get desired water level. ex. if water is to be 3 feet deep in shallow end the depth from finished grade will be 36" + 6" for floor + 3" for water line + 2" for flagstone coping = 47" total from grade line.
- Dig an additional 12" wide x 12" deep footer trench around entire perimeter, It will be poured in conjunction with the pool floor.
- Dig an area out in the deepest part to set the main drains and dig a trench from the main drains to the outside of the perimeter to set the main drain plumbing in. stub plumbing to ground level. cover plumbing with gravel or dirt and use gravel around the main drains to secure them. if the ground is clay or has water drainage issues or underground water is present, install a perforated pipe in the opening on the main drain not used for plumbing and install a hydro stat in the top of the drain under the grate. The perforated pipe should be packed with rock. this will allow water pressure under the floor to come up inside the pool ,preventing the pool shell from floating when empty. leave the gravel low around the drains you want to make sure to get plenty of concrete around them.
- Tie #3 rebar crossways and longways in floor to form a 12" x 12" square grid. If pool is over 6' in the deep end, rebar past the transition (where shallow end starts sloping down into the deep end) should be laid out to form 6" x 6" grids. turn the ends of the rebar up around the perimeter so they will rise above the poured floor. this will give something to tie the block walls to the floor to prevent any chance of shifting.
- Set the rebar cage up off the ground ,this can be done by breaking concrete brick up and placing under the cage . Alternately there are rebar stands designed specifically for this purpose.
- Bond the rebar cage by running a #8 bare copper wire the length of the pool allowing enough wire on the end closest to the equipment to reach all the way there without being spliced and the other end to reach above ground level. Attach the ground wire to the rebar in at least three locations using brass ground clamps.
- The floor is now ready to be poured and finished. finish the concrete with a broom finish, a slick finish is not desirable as it will not accept plaster as well.
- Once the floor has cured adequately. the concrete block walls can be laid up to grade minus the amount for coping being used.
- Holes can be knocked out through the block at this point for all the return plumbing, cleaner line. light niches and any other pipes that need to be installed. Remember here that any block that can't be filled from the top ( such as ones under a light niche) must be filled prior to the accessory being installed.
- Cut out block and set skiimmers in place. alternately a block can be omitted where the skimmer is to be placed and cement brick or concrete used to build a skimmer throat.
- It's a good idea to box in around skimmers so they can be poured with concrete. forms can be made of wood or they can be laid with block and filled when the block walls are filled. skimmers can tend to crack away from the pool if they are not concreted in place. This can cause a leak that is difficult to repair once the deck has been poured. Do it right, do it once.
- Drop a #3 or #4 rebar into each block cavity. it doesn't hurt to leave them a little long as they can be moved around during the block filling to aid in the concrete settling to the bottom.
- Fill each block cavity with concrete.
You now have a concrete block pool shell that is ready to set the tile on and be plastered.
Dimensions For Concrete Pool Dig
Shotcrete Swimming Pool vs. Concrete Block Swimming Pool
I was working through some numbers here . People are trying to save money by building their own inground swimming pool. The going price for shotcrete around here is $115.00 a yard. If I figure a 20' x 40' swimming pool 3' to 8' deep I calculate around 12 yards in the walls at 6" thick.. At $75.00 a yard for shooting and finishing shotcrete plus the price of material i come up with about $2300.00. Figure in a few extra yards for a 12" beam .For that same size pool I figure it will take about 675 block to lay the walls. At $4.00 block (that's block ,labor and mortar) providing you can even find someone to do it for that price these days plus 5 yards of pump mix to fill the block plus $400.00 to hire a pump , you end up with $3600.00 in the pool walls. granted 3000 psi deck mix concrete is a few dollars less a yard than shotcrete, so there is a little money to be saved in pouring the floor, but the $1300.00 saved in shooting the walls should cover the difference in floor pricing should you opt to shoot it as well.
IMO the best way to build your own concrete swimming pool and save money would be to find sub contractors to do the work and not go through a pool company.
By finding subs you can choose which parts of the pool project you want to do yourself and which parts you need to hire out.
Be aware that by not hiring a pool builder you are assuming responsibility for anything going wrong with your pool project.
Even though most reliable swimming pool sub contractors are licensed, bonded and insured, it could be a problem getting repairs made when you have several different crews working on the same project. This is one of the reasons pool builders charge so much for their services.
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