How I Built My Own Pool – Day 3: Pool Floor/Concrete Collar

August 13th, 2015 | Posted by Larry in Inground Pool Kits

There is now a pool in my backyard, and my wife and I couldn’t be happier. Yesterday the walls were erected and the pool steps installed. The equipment pad was framed out and made ready for concrete.

Today, on Day 3 of my inground pool kit installation, the crew is here bright and early for two tasks – pouring the concrete collar around the outside of the pool, and laying a concrete-ish pool floor inside of the pool.

We have 65 bags of Pool Base, aka Pool Mix, which is a mix of concrete and vermiculite that we will mix with water and apply about 2″ thick, to the entire pool floor. A concrete truck is bringing a load of their cheapest mix 2500# – to pour around the outside of the pool, a foot deep and 2.5 feet wide – this is the “concrete collar” that holds the pool walls firmly into the earth.

7 am: With the crew all accounted for, the mixing of the vermiculite begins. We have a rented cement mixer, gas powered to mix up the bagged Pool Base and water. 3 bags are dumped in and water is added until a oatmeal consistency is reached, and then it’s mixed for about a minute. The mixer is tilted to dump the batch into 5 gallon buckets. You can also use a concrete chute, if you have one, or set up a ramp and use a wheelbarrow.  We use the 5 gallon bucket method, filling and carrying them to the pool edge, handing off to a helper inside the pool.

9 am: The floor has progressed to over halfway covered, the deep end and the side slopes are done first. Then the center slope and shallow end floor areas are tamped with the power compactor. Don’t use a “Jumping Jack” type of tamper, use this plate vibrator type of compactor instead. A rope on the handle helps drive it up the slope a bit more easily. Before leveling and flattening the floor, we add more water, spraying a mist to wet the soils. We spray it again right before laying down the Pool Base, so the ground doesn’t suck out the moisture.

11 am: The final buckets of vermiculite are handed in carefully (don’t pour in the mixture, as it splatters and makes divots in the soil). We use a ladder, set up in the deep end, for the final finishing of the pool floor, but you can also work your way out of the shallow end. Remember to not use the steps for anything but to set a radio and cool drinks upon. Set up a ramp and small steps or ladder to enter and exit the pool, safely and securely. It’s a good idea to tape off the steps, to prevent someone from stepping on them before the pool is backfilled.

12:00: After a bit of lunch under the shade tree, the crews prepare for the concrete truck, supposed to arrive in an hour. They pulled a large pool cover over the pool to protect it from any concrete splatter or “accidents”.  Randy brought the cover with him (part of the Rent-a-Randy service).  Next, they pulled open the fence section – the same one that we removed for the excavator on Day 1, to make room for the concrete truck to back up. The truck needs to get very close to the pool, within 15 feet – if grounds are muddy, add gravel and/or sheets of 1/2″ plywood, to prevent wheel ruts.

1:15 pm: The driver is late, but that’s OK, we used the time well, cleaning up a few small cave-ins around the pool, and removing dirt with flat shovels. Then we moistened the soil around the pool walls with a hose. We direct the driver to the pool, close to the edge, checking for any overhead wires or trees that might get in the way. Next we connect the chute extenders to get the concrete into the trench outside the pool. (it’s a good idea to mention that you will need them, when you order the concrete delivery).

2 pm: The concrete flow is turned on/off as needed, so we can keep up with it. The idea is to spread it around the pool, from the wall of the pool to the wall of the overdig, or about 2-1/2 feet wide. It’s never wet enough to actually flow around the pool, so we use shovels and rakes to move it, and also wheelbarrows to transport some. We did the concrete collar pour from one corner of the pool, and carted about 10-15 wheelbarrows full around to the other corner. Then we had him move the truck to pour the equipment pad, which took no time at all.

4 pm: The truck was off and gone by 2:30, but we had more work to do. We used garden rakes to smooth and shake the concrete, which helps it settle and brings air bubbles to the surface. We also had to set up a few concrete dams, using small boards to span small cave-ins to the dirt wall around the outside. Randy and Nate finished up the concrete pad by shaking the concrete into all four corners, then using a 2×4 as a screed to compact and level it. He gave it a slight slope so that water would run off, then gave it a broom finish surface.

Up Next – Day 4: Pool Liner, Plumbing and Electric


Larry Weinberg
SPP Pool Expert


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