Tree Roots and Your Pool: Real Risk and What to Do

Most houses in Volusia County with a pool also have a tree within twenty feet of it, because the tree was there first. The pool deck heaves, a hairline crack shows up in the shell, or the pool contractor says the oak has to go before he will warranty the resurfacing. Then we get the call.

What roots can and cannot do to a pool is more specific than the contractor's blanket answer, and there are usually options short of removing the tree.

What roots do and do not do

Roots do not grow toward water they cannot sense. A pool is a sealed vessel, and a root has no way of knowing it is there. Roots grow where the soil has oxygen, moisture and room, which in a pool area is usually under the deck, because the deck keeps the soil beneath it damp and uncompacted.

Roots do not push through a sound concrete shell. A gunite pool wall is thick, reinforced and continuous, and a root arriving at it goes around or under. What roots do is:

• Lift and crack the deck. The deck is a thin slab on sand. A root growing in diameter under it lifts it, the same as a sidewalk.
• Displace pavers. Easy to fix, and easy to keep fixing.
• Push against the shell from the side over many years. On an older pool, a very large root bearing directly on the wall can contribute to a crack, usually along with soil movement and other stress. It is uncommon and it is a slow process.
• Clog the plumbing. This is the real one. Roots find the tiny leaks at pipe joints in the suction and return lines and grow into them. A pool that keeps losing water and a skimmer line that keeps clogging can be a root problem.

Which trees cause trouble

Fast-growing, shallow-rooted, water-loving species are the ones that end up in the plumbing and under the deck: laurel oak, water oak, sweetgum, camphor, ficus, willow, and red maple in wet ground. Live oak has a big, aggressive root system too, but it grows slower and the problems develop over a longer time.

Palms are close to harmless around pools. Their roots are thin, numerous and non-woody, and they do not lift slabs or crush pipes. If you want shade near a pool, a palm is the safe choice, which is why they are there.

Options that keep the tree

Root barrier at the deck edge

A vertical barrier installed in a trench between the tree and the pool deck deflects roots downward and away. It works when it is installed correctly, deep enough, and when the roots it cuts are not the tree's main anchorage. We covered how barriers actually perform in Root Barriers: What They Do and Where They Actually Help. On a mature tree already close to the pool, the barrier trench itself may cut too many roots to be safe; that is a site call.

Selective root pruning

One or two problem roots heading under the deck can sometimes be cut, at a distance from the trunk that leaves the tree stable, and the deck repaired. The rules from Root Pruning Before Construction apply: smaller, farther, fewer, clean.

Fix the plumbing, not the tree

If the issue is roots in the lines, the fix is the lines. Rerouting or replacing the section with solvent-welded PVC and no leaks removes the thing attracting the roots. Killing the tree does not fix a leaking pipe.

Live with the deck

Pavers over a root zone are the practical choice. When a root lifts them, pull them, shave the sand, reset. A poured slab cracks; pavers move and come back.

When the tree should go

• It is a short-lived, storm-prone species (laurel oak, water oak) and it is over the pool cage
• Roots have already compromised the shell or the equipment pad and the tree is close enough that any real fix cuts its anchorage
• It is dying or structurally defective and the pool is the target

A tree over a screen enclosure is worth a separate thought regardless of roots. A limb through a pool cage is expensive and common, and a tree that drops limbs, or one whose structure is questionable, is a bigger risk to the enclosure than its roots ever will be to the shell. We look at both on a site visit, and our tree removal work around pools is planned to protect the cage.

Planting near a pool

Set large trees back at least the eventual canopy radius from the deck edge. Choose palms, or small trees like crepe myrtle and ligustrum, for the spots close to the water. Avoid the fast, thirsty species listed above within thirty feet. And do not plant anything that drops fruit or heavy leaf litter directly over the water; the filter will tell you.

Frequently asked questions

Will removing the tree stop the deck from lifting?

It stops new lifting. The roots already there do not disappear; they decay over years. Grinding what is accessible and resetting the deck is usually done at the same time.

Can you grind roots under the deck?

Only where the deck is removed. Roots under an intact slab are dealt with when the slab is replaced.

My pool is losing water and there is a big oak nearby. Is it the roots?

Possibly. A leak detection service can tell you where the water is going. If it is a line under the root zone, roots are a likely culprit. Fix the line; then decide about the tree.

How close is too close for a live oak?

A mature live oak within ten feet of a pool deck is going to lift it. Within twenty, expect some paver movement over time. The shell itself is rarely the problem.

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ArboristRX assesses trees near pools and enclosures across Edgewater, New Smyrna Beach, Port Orange, Oak Hill and Volusia County. Call (386) 444-5959 before the pool contractor makes the tree decision for you.