Centennial Concrete Pools

Do this on a Saturday morning before anybody gets in. Start at one corner and walk the whole perimeter slowly, looking down. Step on each coping stone. Watch where the deck meets the tile. Then look out into the lawn on the downhill side. Almost every serious problem a concrete pool has announces itself along that walk, months or years before anybody calls a builder.

We get called for both halves of this trade here: new shells for homeowners building the back yard they always wanted, and second opinions on older pools in Southglenn and Walnut Hills where somebody was handed a number that felt like a guess. Either way the conversation starts with structure, because the shell is the part you can't redo later. Tile, plaster, and coping are finishes. The concrete is the pool.

The walk, in order

Coping first. Press down on each stone with your foot. One that rocks or clicks has lost its bed, which usually means water has been running behind it into the bond beam for a while. Look at the sealant line between coping and deck while you're there. Cracked open or missing, and you've found the entry point.

Next, the tile band at the waterline. A hairline in the grout is nothing. A crack running through tile, grout, and down into the plaster in one line is a different animal.

Then the plaster. Fine crazing over the surface is a finish condition and it's common. A crack you can catch a fingernail in, running from a corner or a step, is structural until somebody proves otherwise. Rust bleeding through in a vertical streak means steel is corroding.

Finally, the lawn. A green stripe staying wet downhill while the rest of the yard is dry is water going somewhere it shouldn't.

What the symptom is telling you

How we build a shell that doesn't do any of that

Engineering comes first, not last. Soil varies lot to lot here, and a hole holding tens of thousands of gallons is a structure, so it gets designed as one. Our in-house structural engineer sets wall thickness, bar size and spacing, and how floor and walls tie together at the cove. That drawing is what the steel crew builds to and what we inspect against before anybody sprays concrete.

For placement, shotcrete goes on nearly every residential pool. Concrete shot at velocity into a tied cage consolidates around the bar, follows curves, and lets us build free-form shapes without forms on both faces. Cast-in-place is a real method and it belongs on rectangular shells formed both sides, or where a wall is part of a larger structure. More time, more formwork, straight sides.

Then the boring part that decides everything: the cure. A fresh shell stays wet for days, hose crew back morning and evening, because concrete that dries too fast gains less strength and cracks underwater. Plaster waits until we're satisfied.

What our concrete scope covers on a pool

• Engineered shell drawings, sealed, with the steel schedule spelled out
• Excavation shaped to the design, over-dig held to what the crew actually needs
• Steel tied and inspected, chairs holding real cover over every bar
• Plumbing held under pressure through the shoot so a break shows itself
• Shotcrete placed by a nozzle crew that does this daily, cut and screeded to line
• Wet curing on a schedule, not left to the weather

Building on the Front Range calendar

Break ground in the fall if you want to swim the following summer. That surprises people who call in May expecting water by July, but a pool is a sequence of trades with waiting built into every step.

Cold doesn't stop shell work outright. We shoot into the fall, watching overnight lows, protecting fresh concrete with blankets and adjusting the mix when we need to. What we won't do is place onto frozen ground or let a green shell take a hard freeze unprotected. Excavation is what really slows once frost is in the soil.

Then the first year. Watch water chemistry on new plaster, keep the deck joints sealed, and pay attention to where roof and irrigation water goes around the pool. The soil around a shell is the one thing you keep influencing after we've gone.