Gunite or Fiberglass: Choosing a Pool Shell That Fits Your Nashville Backyard

A pool is usually the biggest single decision in a backyard project, and the first real fork in the road isn't the tile or the coping, it's the shell underneath everything else: gunite or fiberglass. Both are legitimate, well-proven ways to build a pool in Middle Tennessee, and neither is automatically the right call for every yard. What actually decides it is how you want to use the water, how the lot is shaped, and how much you want the pool to bend around a specific design idea rather than the other way around.

Gunite: a shell built to match the site

Gunite pools start as a steel rebar cage set into the excavation, then a mix of concrete and sand is sprayed over it under pressure and shaped by hand. Because the structure is built in place rather than dropped in whole, a gunite pool can take almost any shape a design calls for: a rectangle with a raised spa spilling over one wall, a freeform curve that follows a slope, a sun shelf cut into one end, a negative edge if the grade allows it. Once the shell cures it gets a finish coat, often plaster or a pebble finish like PebbleTech, which is what actually gives the water its color and texture underfoot. The tradeoff is time. A gunite build has more steps and more curing time than a manufactured shell, so it's a longer process from groundbreaking to first swim.

Fiberglass: a manufactured shell, delivered whole

A fiberglass pool works the opposite way. The shell is built off-site to a mold, trucked in whole, and set into an excavated hole, often in a single day, then backfilled and decked around. The gelcoat surface is smooth and resists algae better than plaster, which usually means less time spent on chemical maintenance over the years. The catalog of shapes is set by the manufacturer rather than drawn from scratch, so if a design calls for something outside that catalog, gunite is the only way to get there. Brands like Imagine Pools, Thursday Pools, and Latham Pools each have their own range of shapes and sizes, and a builder who works with several of them can usually find something close to what a homeowner has in mind.

What Middle Tennessee clay actually does to the decision

Anyone who has dug a fence post hole in this part of the state knows the soil isn't forgiving. Middle Tennessee's clay-heavy ground holds water differently than sandy or loamy soil, which changes how excavation, backfill, and drainage around the pool shell get handled, whichever shell you choose. A good design accounts for where water actually wants to go on the lot after a hard rain, not just where the pool sits when it's full. This is less about which shell type is better on clay and more about making sure the site work, grading, and drainage plan are done right regardless of what's going into the ground.

• Shape freedom: gunite can be built to almost any custom shape; fiberglass is limited to the manufacturer's mold options
• Timeline: fiberglass installs faster once the shell arrives; gunite takes longer because it's built and cured on site
• Surface feel: plaster and pebble finishes on gunite have more texture; fiberglass gelcoat is smoother underfoot
• Long-term upkeep: fiberglass gelcoat generally resists algae better; gunite finishes can be resurfaced when they wear

Built to be used more than four months a year

A pool that only gets used in July and August is leaving a lot of the investment on the table. Automatic pool covers help retain heat overnight and keep debris out between swims, and energy-efficient pool equipment makes it realistic to keep the water warm enough to use well outside the hottest stretch of summer. A personal spa built into the same design, whether it's a raised spillover spa on a gunite shell or a standalone spa unit, gives you a warm-water option on cooler evenings even when the main pool isn't in use. None of that is about the shell material specifically, it's about designing the whole system, water, cover, equipment, and spa, to actually get used.

One design-build project, not three separate crews

The bigger point, honestly, is that the shell decision doesn't happen in isolation. Allin Landscaping builds every pool as part of a complete backyard environment, pool, spa, outdoor kitchen, covered pavilion, fire features, patios, lighting, drainage, and landscaping designed as one project rather than handed off between separate contractors. George Allin has spent nearly thirty years working in landscaping and pool construction across greater metro Nashville, Brentwood, Franklin, and Williamson County, and the company is a Licensed General Contractor with the State of Tennessee, fully insured, and a Best of Houzz award winner every year since 2017. Whichever shell fits your yard, that's the conversation worth having before anything gets dug.