ICF vs gunite concrete pools: what is the difference?

Gunite is sprayed concrete. The American Shotcrete Association uses shotcrete as the umbrella term for concrete placed pneumatically through a hose, and it splits the method in two. In the dry-mix process, which the pool trade has long called gunite, dry cement and sand travel through the hose and water is added at the nozzle. In the wet-mix process, usually just called shotcrete, the concrete is mixed with water at the plant and pumped wet to the nozzle.

For a pool, the crew digs the shape, ties a cage of steel reinforcing bar to follow the floor and walls, and sprays concrete over and around it, shaping the shell by hand as it goes. After it cures, the shell gets a finish, most often plaster, and then tile, coping and the deck.

With dry-mix, the nozzle operator controls the water in real time, so the quality of the shell depends heavily on the skill of that one person. Pool & Spa News quotes gunite builders who value exactly that control. The same trait means a good crew matters more than the brand of anything.

Wet-mix shotcrete is the other sprayed option. The concrete comes from a ready-mix plant already combined with water and is pumped to the nozzle, so the water content is set at the batch plant rather than by the operator. In an article published by the American Shotcrete Association, one pool contractor explains that it uses dry-mix for smaller pools, under about 1,000 square feet, and sees real benefits from wet-mix on larger ones. Both methods can produce excellent shells in skilled hands. When a builder says gunite, ask which process they mean.

ICF stands for insulated concrete forms: hollow blocks of expanded polystyrene foam that interlock like oversized bricks. The crew stacks them on a footing to the height and shape of the pool walls, places steel inside, then fills the forms with concrete. The foam stays on both faces of the wall as permanent insulation. The floor and interior finish follow, and the rest of the pool is built as usual.

Nudura points out that ICF walls do not need an exact excavation, because any overdig behind the walls is simply backfilled once the walls are up. The walls are formed by the blocks, not by the shape of the hole.

The short version of that table: both methods produce a reinforced concrete pool that can take almost any shape, and both depend on a skilled crew. ICF builds insulation into the walls and moves the critical work into forming and pouring. Gunite puts the critical work in the hands of the nozzle operator and leaves the walls uninsulated. In a warm climate that last difference barely matters. In Northeast Ohio, where a heated pool fights cold ground for much of the season, it matters a lot.

ICF, by design. A gunite shell is solid concrete against the soil, and concrete conducts heat. In Northeast Ohio, where the ground stays cold well into spring and nights cool quickly in late summer, a heated gunite pool is constantly losing some of its warmth into the dirt around it. ICF puts a layer of foam between the concrete and the soil.

Manufacturers make strong claims for the difference. BuildBlock says ICF pools stay 5 to 10 degrees warmer naturally and that its foam prevents more than 80% of heat loss to the ground. Those are a manufacturer's numbers, not independent tests, and real results depend on the floor, cover use and weather. What is not in doubt is the physics: an insulated wall loses less heat than a bare one, and every degree the ground does not take is a degree your heater does not have to replace.

Both can last for decades in a cold climate when they are built right. Pool & Spa News, writing about high-end pools in cold regions, notes that concrete for these climates must be stronger and better able to resist freezing and thawing, and that keeping water in the mix low and using air entrainment both improve freeze-thaw resistance. That applies to sprayed and poured concrete alike.

ICF adds one advantage here: the foam keeps the concrete out of direct contact with wet, freezing soil. Gunite relies on good drainage behind the shell and a sound finish to keep water from working into the concrete. Either way, the winter routine matters: lower the water, blow out and plug the lines, drain the equipment and cover the pool.

It depends on the design more than the method. Angi's 2026 gunite guide puts yearly maintenance for gunite pools at $2,700 to $4,000, with an acid wash every few years at $250 to $1,000 and replastering roughly once a decade at around $10,000. Those costs come mainly from the plaster finish, so an ICF pool with a plaster interior carries similar finish upkeep. An ICF pool with a vinyl liner interior trades plaster work for an eventual liner replacement.

On build cost, BuildBlock claims ICF pools cost around 10% less than gunite and build in about 30% less time. Treat that as a claim to test, not a promise. The fair comparison is two quotes for the same pool on the same lot. We can price both if you want to see the difference for your design.

Both are custom concrete pools and sit in the concrete tier of pool pricing, above our fiberglass packages, which start at $68,400 installed.

Each has an edge in different situations. ICF blocks are light enough to carry by hand, so they reach backyards where a truck cannot. Gunite material is pumped through hoses that can run a long way from the street, which also helps on hard-to-reach lots. On a sloped lot, both can be built with one side of the pool raised, but an ICF wall that stands partly above grade is already insulated where it is exposed to the air, which a bare concrete wall is not.

Both are multi-stage builds and take longer than setting a fiberglass shell. A gunite pool needs excavation, steel, spraying, a curing period, then tile, coping and plaster. An ICF pool needs excavation, a footing, the forms, steel, the pour, the floor and the finish. BuildBlock claims ICF builds in about 30% less time than gunite, which is plausible for simpler layouts, but schedules depend far more on design complexity, inspections and weather than on the wall method. In Ohio, plan concrete work for the warm months, when new concrete can cure without protection from frost.

• Which method will you use, and why for my design?
• Who does the concrete work, your own crew or a subcontractor?
• How is drainage handled behind and under the walls on a wet lot?
• What concrete strength and mix are specified for freeze-thaw exposure?
• What interior finish is included, and what will it need over 10 years?
• What does the warranty cover on the structure and on the finish?

If you want a highly sculpted, freeform pool with organic curves everywhere, like a lagoon with rock features, gunite's hand-shaping is hard to beat. It is also the choice if you have your heart set on a specific plaster or aggregate finish and a builder's gunite portfolio you love. We offer gunite on request.

For most custom concrete pools in Northeast Ohio, especially heated ones, we lean toward ICF. The insulation works for you every day the pool is warmer than the ground, which here is most of the season. The modular build suits a lot of the older, tighter lots in our area. And the shapes you can form with ICF, including curves, lap lanes and raised spa walls, cover almost every design people bring us.

Either way, we start with a 3D design on your lot, handle the permits and price the pool line by line. Financing is available through lenders including PoolLoan.net and HFS Financial.