Concrete Pool Bottoms 101
When you think of concrete you think of a flat, hard, "cold" surface that isn't pretty. If so, that is perfect as that is exactly right. One of the oldest methods of pouring a floor for a vinyl liner pool is with concrete.
A concrete pool bottom uses a special recipe that includes more sand, less stone, along with fly ash slag. The concrete is poured 2" - 4" thick and gets hand troweled to a smooth glass like finish.The surface is smooth and not abrasive . . . basically think of your garage floor the day it was poured, perfectly smooth.
That perfectly smooth, flat floor is a perfect substrate for your liner to sit on.
Why a Concrete Pool Floor?
A pool floor needs to hold its shape and transition lines (also called cut lines) over time to make future liner replacements easier and less costly.
- A Concrete pool bottom will hold there shape and never erode away over time. The concrete floor is roughly 3,000psi (much stronger than it needs to be) but with that strength comes time duration.
- Sand & vermiculite pool bottoms will need patching every time the liner is replaced.
- Concrete pool floors will cost more for the pool contractor to pour but it will last 2 - 3 times longer.
- Sand & vermiculite are both very popular in the US because of their price and ease of installation. Both are VERY easy and cost MUCH less than pouring with concrete.
- Concrete bottoms will not divot or erode away. Trowel marks aren't visible through the liner at night.
- Sand will divot easier than vermiculite, but both will divot leaving an impression in the floor. Most impressions & trowel marks aren't noticeable until you turn the lights on at night.
- These bottoms are porous and will allow water to pass through it over time, which can cause a floating vinyl liner if you have a high water table.
Liner Replacements with a Concrete Floor
Inground pool builders love working on vinyl liner pools that have a concrete pool bottom as they can work through the rain. Rain will not hurt the concrete in any way and actually helps the pool contractor wash the floor as they get ready to set the liner.
With a sand pool bottom, replacing the liner in the rain is a big no-no. The rain will speed up the erosion of the bottom and make twice as much work for patching the bottom.
Are Vinyl Liner Concrete Pool Floors Better?
Cost vs Longevity?
Fewer and fewer pool contractors are able to pour concrete pool floors as it is harder and more demanding than sand or vermiculite; however you need to ask your self if you want a lower cost or a longer better product?
concrete floors will last longer, hold back ground water, and have a better finish . . . but you are going to pay more for your inground pool prices.