Gunite & Concrete Pools in Bethesda, MD

Gunite and concrete pools take shape on site: the excavation follows the design outline, rebar is tied into a reinforcing grid against the soil, the plumbing goes in, and concrete is sprayed onto the steel at high velocity. Gunite uses dry mix that is hydrated at the nozzle; shotcrete arrives wet from a mixer. Either way, the result is a structural shell that can take any outline, depth or built-in feature, then a finish coat that makes it watertight and smooth.

What happens at each stage

• Layout and dig: the pool shape is painted on the ground and excavated, with soil hauled off site or reused for grading.
• Steel: rebar is tied on a grid that follows the walls, floor, steps and benches.
• Plumbing: main drains, returns, skimmer lines and spa jets are set and pressure-tested.
• Bonding inspection: Montgomery County inspects after excavation and steel, when the electrical bonding grid is checked.
• Shotcrete or gunite: the shell is sprayed and shaped, then kept damp while it cures.
• Tile and coping: waterline tile and coping stones go on before the deck.
• Interior finish: plaster, quartz or pebble is troweled on and the pool is filled right away.

Finish choices and how long they last

The interior finish is what you see and touch. HomeGuide's resurfacing guide lists standard plaster at about $6 to $8 per square foot with a 7- to 12-year life, quartz plaster at $7 to $10 lasting 10 to 15 years, and pebble at $7 to $15 lasting 15 to 20 years or more. Pebble costs more up front but is rougher underfoot and more durable; plaster is smooth and classic white or tinted. Waterline tile can be ceramic, porcelain or glass, and it is the line most people notice first.

Concrete and Maryland winters

Montgomery County designs houses for a 30-inch frost depth and classifies concrete weathering as severe. A pool shell is protected by the water it holds, which is why concrete pools are normally kept full through the winter, with the water lowered below the skimmer and lines blown out and plugged. The parts that suffer most are the coping and deck, where water freezes in joints. We set coping on a proper mortar bed, leave expansion joints between coping and deck, and pitch the deck toward the yard so meltwater does not sit at the edge.

Timeline and ownership

HomeGuide estimates six to eight weeks to build a gunite pool, depending on size and site work, and a lifespan of 50 years or more for the shell. The trade-off is upkeep: concrete is porous, so it takes a bit more brushing and chemistry than fiberglass, an acid wash every few years, and a new interior finish on a 7- to 15-year cycle. We explain those costs before you choose so there are no surprises later.

When concrete is the right call

Choose gunite if your yard needs an unusual size or shape, if you want a deep end, a tanning ledge, an attached spillover spa, a beach entry or a vanishing edge, or if a crane cannot reach the back yard for a fiberglass shell. Concrete trucks and pump hoses can reach a back yard through a narrow side yard where a 15-foot-wide fiberglass shell cannot.