Commercial pool construction field guide: the shotcrete shell

What a commercial concrete pool actually is

A commercial concrete pool is an engineered, reinforced shotcrete or gunite shell. It is a watertight concrete structure, not a lined hole, and it has two loads to carry that pull in opposite directions. Full, it holds tons of water pushing out and down against the soil. Empty, it has to resist the groundwater pushing up from underneath, and that is the load that wrecks pools nobody engineered.

The build runs in a fixed order: lay out the shape, excavate, tie the steel, rough in the plumbing, shoot the concrete shell, set the tile and coping, pour the deck, and finish the interior with plaster or an aggregate. Get the order wrong, or skip a step like pressure-testing the plumbing before the shell buries it, and the fix is a jackhammer.

Two things govern the whole job and neither is optional. The first is the structure and the soil, because a pool is an engineered concrete structure designed by an engineer for the loads and the ground it sits in, and an empty pool without a hydrostatic relief valve can float out of the ground. The second is the safety code, because the main drains can trap and drown a swimmer and the depth and markings are health-department law. The circulation system, the pump, filter, heater, and chemistry, is a separate trade. That side lives in the pool and spa mechanical guide. This guide is the structure you build it into.

A pool is an engineered structure, not a hole

The single most important truth on a concrete pool job is that you are building a reinforced concrete structure, not digging a hole and lining it. The shell is designed to resist water pressure from the inside when it is full and earth and groundwater pressure from the outside when it is empty, and those are real structural loads that a structural or geotechnical engineer sizes the steel and the concrete thickness to handle.

Treat it like a hole and the failures are structural, not cosmetic. The shell cracks through, it leaks, the floor heaves, or the whole thing lifts. None of that buffs out. A residential spec might lean on a builder's standard detail, but a commercial pool, with its depth, its bather load, and its public liability, gets a stamped design more often than not, and the AHJ usually wants to see it.

Let the engineer own the structure. The shape, the depth transitions, the steel schedule, the shell thickness, the bond beam, the soil bearing, and the hydrostatic relief are an engineered package, and the contract documents and the engineer of record control them. Build to the drawings. When the field condition does not match the soil report or the drawing, that is an RFI, not a field call. The day you guess on a pool structure is the day you own the crack.

Hydrostatic uplift: an empty pool can float out of the ground

This is the hazard that surprises people who have never built one: an empty concrete pool can float up out of the ground. Groundwater under and around the shell pushes up with real force, and when the pool is full that weight holds it down. Drain it with a high water table and there is nothing holding it. The shell lifts, cracks, and rotates, and a heavy gunite shell has popped feet out of the ground in places like Florida where the water table is high.

The defense is a hydrostatic relief valve, sometimes called a hydrostat. It sits in the main drain sump or the floor, over a gravel pocket, and it lets groundwater flow up into the pool to equalize the pressure when the level outside gets higher than the level inside. The pool takes on a little water instead of floating. On many commercial pools the relief is engineered with a gravel sump and perimeter drainage, and the design belongs to the engineer who knows the soil and the water table.

The blunt rule: never drain a concrete pool without addressing the groundwater. If there is a hydrostatic relief valve, pull the plug so it can do its job, and confirm the water table is low before you empty the shell. If you are not certain about the groundwater, get the engineer involved before the pump comes on. Drain a pool with a high water table and no relief and you can float a structure that cost six figures, and there is no putting it back.

The soil, the water table, and bearing

The pool sits on and in the soil, and the soil decides what the structure has to do. The engineer designs the shell for the water loads and for the ground: the bearing capacity under the floor, the lateral earth pressure on the walls, and the groundwater that drives the uplift. A geotechnical report or soil borings inform that design on a commercial job, and the design is only as good as the soil information behind it.

Expansive clay, uncompacted fill, organics, and a high water table each change the answer. Clay that swells and shrinks with moisture can crack a shell that was fine in sand. Fill that was never compacted settles, and the floor goes with it. The engineer accounts for what the soil report shows, which is exactly why the soil report has to be real and the over-excavation has to be backfilled and compacted to spec, not eyeballed.

If you hit groundwater in the excavation, or the soil does not match the report, stop and document it. Dewatering during the build, the sub-base preparation, and any soil treatment are engineered calls. Footings, bearing, and soil-structure interaction by topic belong with the engineer and the geotechnical report, and the contract documents and the AHJ control the requirement.

The build sequence, in order

Concrete pool construction runs in a sequence, and each step locks in the one before it. You cannot shoot the shell until the steel and plumbing are inspected, you cannot tile until the shell has cured and the bond beam is right, and you cannot plaster until the tile, coping, and deck are done. Run the order in the table and the job flows. Break it and you are demolishing finished work to fix something underneath.

The two gates that catch crews are the steel-and-plumbing inspection before the shotcrete and the plaster start-up at the very end. The first buries everything structural and mechanical in concrete, so it has to be right and inspected first. The second is a chemistry-sensitive process that can stain a brand-new finish in a day if it is botched.

Layout and excavation

Layout sets the pool on the ground: the shape, the dimensions, the depth profile, the elevations, and the relationship to the deck, the building, and the equipment pad. Get the elevation wrong here and you fight it for the rest of the job, because the coping, the deck slope, the waterline, and the gutter or skimmer all reference it. Shoot the grades and verify the layout against the drawings before the excavator moves dirt.

Excavation digs to the shape plus an over-dig allowance, because the shell has thickness and the steel needs cover and room to work. The crew cuts the floor, the walls, the slopes, and the deep-end transition, then prepares the sub-base the floor bears on. On firm native soil the floor can bear directly; on fill or poor soil the sub-base is engineered and compacted, and the over-excavation gets backfilled to spec.

Two field problems show up at the dig. Over-digging the deep end and not compacting the replaced material leaves a soft spot under the floor, and undercutting the walls so the steel cannot get its cover sets up a thin shell where it is weakest. If groundwater shows up in the hole, deal with it before the steel goes in. The dig is where the geometry and the soil get committed, so it is worth the time to check both.

The steel: the rebar cage and the bond beam

The steel is the strength of the shell. It is a continuous cage of reinforcing bar, commonly a grid of #3 or #4 bar tied at a spacing the engineer sets, often around 10 to 12 in each way, with the floor, the walls, and the bond beam tied into one structure. The grid resists the tension the concrete cannot, and on a commercial pool the bar size, the spacing, and any added steel at the bond beam and the corners come off a stamped drawing, not a rule of thumb.

The cage has to float in the shell, not lie on the dirt. Concrete cover, the layer of shotcrete between the steel and the soil and between the steel and the water, is what protects the bar from corrosion and lets the section work. The crew holds that cover with chairs, dobies, or supports so the cage sits up off the sub-base and stands off the excavated walls, and the bars get tied, lapped, and supported so they do not move when the nozzle hits them. Steel lying in the mud or pushed to one face is steel that rusts and a shell that cracks.

The bond beam is the thickened, reinforced top perimeter of the shell, and it carries the tile, the coping, and the deck edge while tying the walls together at the top. It usually gets extra horizontal bars; a common detail is several #4 bars run continuously around the perimeter. The exact schedule is the engineer's. Get the steel inspected before the shotcrete, because once the shell is shot, nobody can see the cage again.

The plumbing rough goes in before the shell

The plumbing rough is installed and tested before the shotcrete, because the shell encases it permanently. The suction side, meaning the main drains at the deep point, the return lines that push filtered water back, the skimmers or the gutter, and any spa, water-feature, or fill lines all get roughed in and tied to the steel so the nozzle can bury them in the shell. Once the concrete is on, those lines are in the structure for good.

Pressure-test every line before the shell goes over it. This is the step that separates the pros from the callbacks. The plumber caps the lines and puts them under air or water pressure, then watches the gauge hold while the steel inspection happens, so a leak in a fitting or a line shows up now, while it is a glued joint you can cut out, instead of after it is sealed in shotcrete and buried under the deck. A line that fails after the shell is a leak you chase with a hammer.

The plumbing layout, the pipe sizing, the turnover math, and the hydraulics are the mechanical trade's design, covered in the pool and spa mechanical guide. From the structure side, the job is to get the rough set in the right place, tied so it does not move under the spray, and pressure-holding before the shell. Confirm the lines hold and stay under test through the shoot, and confirm the layout against the mechanical drawings.

The main drains have to be VGB anti-entrapment

The main drain is the one part of a pool that can kill, and you build the protection into the shell. The pump pulls suction on the main drain at the deepest point, and a body or a length of hair over a non-compliant drain can be held there with enough force to trap and drown a swimmer or, in the worst documented cases, disembowel a child. Anti-entrapment is federal law under the Virginia Graeme Baker Pool and Spa Safety Act, administered by the CPSC, not a recommendation.

Build it in at the rough stage. The compliant approach on a commercial pool is dual main drains, spaced far enough apart, commonly at least 3 ft, that a single body cannot block both at once, fitted with anti-entrapment covers listed to the current ANSI/ASME A112.19.8 standard. Where a single drain or other risk remains, the system needs a secondary layer such as a safety vacuum release system (SVRS) that detects a blockage and kills the suction. The covers carry a service life and have to be replaced before they expire.

Set the drain sumps, the dual spacing, and the conduit for the covers into the shell now, because retrofitting compliance into a finished pool is expensive and sometimes means re-coring the floor. The specific cover listing, the spacing, the SVRS requirement, and the inspection are governed by the VGB Act, the cover standard, and the adopted health code, and the anti-entrapment design ties into the mechanical system in the pool and spa mechanical guide. Confirm every detail with the AHJ. This is a place to be certain, not close.

The shotcrete or gunite shell

The shell is the structure, and it is pneumatically applied concrete: shotcrete or gunite shot through a hose at high velocity onto the steel and the excavated faces, where the force of the impact consolidates it without a form on the inside. The nozzleman shoots the floor, the walls, the bond beam, and the steps in one monolithic placement, encasing the cage and gauging the material to the thickness on the drawings. The application is the quality, and the full detail of the process lives in the shotcrete and gunite guide.

The failures in a pool shell are the failures of any shotcrete placement, and they hide behind the rebar. Shooting at the wrong angle traps rebound and overspray behind the bars and leaves voids and sand pockets, pockets of loose, weak material with no paste, exactly where the steel is supposed to be encased. Those voids are where the shell leaks and where the steel rusts. A good nozzleman blows the rebound out instead of burying it, encases the bar from the back, and the crew checks the thickness as it builds so the section is not thin where it matters.

Gauge the thickness, encase the steel completely, keep the rebound out of the work, and then cure it. A pool shell that is shot void-free to the engineered thickness is a watertight structure. A shell full of sand pockets is a leak and a corrosion problem you cannot see until the pool will not hold water. The structural shell, the thickness, and the acceptance criteria are governed by the engineer, the ACI shotcrete guidance, and the contract documents.

Gunite versus shotcrete: what is the difference?

Gunite and shotcrete are the same idea applied two ways, and in the pool trade the words have specific meanings. Gunite is the dry-mix process: dry cement and sand go through the hose and the water is added at the nozzle by the nozzleman, who controls the mix by feel and sound as it sprays. Shotcrete in the pool world usually means the wet-mix process: the concrete is batched complete with water, pumped through the hose, and shot already mixed.

Dry-mix gunite is the long-standing pool method, flexible for a crew moving around a complex shape and tolerant of stop-and-start work, but the water content rides on the nozzleman's hands, so the consistency depends entirely on the operator. Wet-mix shotcrete batches the water-cement ratio at the plant, which takes that variable out of the nozzleman's hands and tends to put more material in place faster, at the cost of needing a pump and a continuous supply.

Both build sound pool shells when the operator is good and both fail the same way in bad hands, with voids and sand pockets behind the steel. The choice is a means-and-methods call for the crew and the spec, and the wet-versus-dry decision, the equipment, and the nozzleman's role are covered in the shotcrete and gunite guide. What does not change between them is that the placement has to encase the steel void-free.

Curing the shell

Cure the shell or it does not reach the strength the design assumed. Concrete gains strength through hydration, a chemical reaction that needs water and time, and a freshly shot pool shell exposed to sun and wind dries out at the surface before that reaction finishes. The standard pool practice is a water cure: keep the shell wet, often by hosing it down several times a day or running a soaker over it, for the curing period the spec calls for, commonly around a week.

Skip the cure and you get a weaker shell and surface crazing and shrinkage cracks as the concrete dries too fast. Those cracks are not just cosmetic on a structure that has to stay watertight, and they can telegraph through the plaster later. The cure window is also when the crew is tempted to move on to the next trade, so it gets shortchanged.

Curing time and method vary with the weather and the mix, and they run longer in hot, dry, or windy conditions where the surface loses water fastest. Follow the curing requirement in the specification and the ACI shotcrete guidance rather than a fixed number of days, and keep it wet the whole window. The strength you are protecting is the strength the engineer designed the shell around.

The bond beam at the top

The bond beam is the thickened, reinforced band at the very top of the shell that runs the whole perimeter. It ties the tops of the walls together, resists the spreading load the water puts on the upper walls, and gives the tile, the coping, and the deck edge something solid to land on. It is the structural top of the pool, and it is where the waterline tile sets, so its elevation and its line set the finished waterline.

Get the bond beam shot to the right elevation and the right width, with its extra steel continuous around the perimeter and no voids at the back of the bars. A weak or out-of-level bond beam shows up later as a coping line that will not sit flat, tile that cracks, or a waterline that is high on one end. Because everyone can see this band, the errors here are the ones the owner notices first.

The bond beam detail, the added reinforcement, and the dimensions are part of the engineered shell. The tile-and-coping line that rides on it is the next section.

Waterproofing the shell

The concrete shell is the primary water barrier. A properly proportioned, void-free, well-cured shotcrete shell with full steel cover is meant to be watertight on its own, which is why the placement quality and the cure matter as much as they do. The interior finish, plaster or an aggregate, adds a surface and a measure of protection, but it is not what holds the water back if the structure underneath is full of sand pockets.

Where the design calls for it, a waterproofing membrane is added, and the side it goes on matters. A negative-side or interior waterproofing system can be specified under the finish on shells where groundwater or the construction demands it, and there are cementitious and other systems made for pool shells. Whether a membrane is required, and which one, is a design decision tied to the soil, the water table, and the engineer, not a default.

The leak you do not want is the one that shows up after the pool is finished, because chasing it means cutting the finish or the deck. The defense is upstream: a sound shell, the right cover, a real cure, and any specified waterproofing applied per the manufacturer. Confirm the waterproofing requirement against the contract documents and the engineer.

Waterline tile and coping

Once the shell is cured, the waterline tile and the coping go on the bond beam. The waterline tile is a band of tile set at the water level, where it takes the scale, the oils, and the scrubbing that the plaster below it should not have to, and where it gives a clean, cleanable line at the surface. It is set in a bond coat over the bond beam and has to run dead level to the water, because the eye reads any slope against the waterline instantly.

The coping is the cap on the edge of the pool, the piece you grab and the transition from the shell to the deck. It can be cantilevered concrete, precast, or natural stone, and it has to shed water away from the pool and give a finished, non-sharp edge. The detail that gets skipped is the expansion joint between the coping and the deck. The deck and the pool move independently, and without a flexible joint there, the deck pushes the coping and cracks the tile or the coping itself, a problem that gets worse where freeze-thaw works the joint every winter.

Set the tile to the waterline, set the coping to shed away from the pool, and put a real expansion joint between the coping and the deck. In freezing climates, the materials and the setting method have to tolerate freeze-thaw, so confirm the products and the joint detail against the spec and the manufacturer.

The pool deck

The deck is the slab around the pool, and its job is to move water and people safely away from the water's edge. It has to slope away from the pool so splash and rain drain off the deck instead of carrying dirt and contaminated water back into the pool, and on a commercial deck that drainage is usually formalized with deck drains and a defined slope the health code sets. Slope it toward the pool and you have built a funnel for everything on the deck.

The surface has to be slip-resistant, because a pool deck is wet by definition and a smooth troweled finish is dangerous around water. A broom finish, an exposed aggregate, or another textured surface gives the traction, and the commercial code typically calls for a non-slip surface and a minimum unobstructed deck width around the pool.

The deck and the pool are two structures that move on their own, so the expansion joint between the deck and the coping has to be real and maintained, the same joint covered in the tile-and-coping section. Deck drains, the slope, the slip resistance, and the perimeter width are health-code items, so confirm them against the adopted code and the AHJ. Build the deck to drain away, to grip wet feet, and to move without dragging the coping with it.

The interior finish

The interior finish is the surface the water and the swimmers touch, applied over the cured shell as the last major step. The traditional finish is white plaster, sometimes called marcite, a cement-and-marble-dust coat troweled onto the shell. Aggregate finishes, the exposed-pebble and quartz surfaces, are cement mixed with stone that is troweled on and then washed or polished to expose the aggregate, and they hold up longer than plain plaster and hide etching better. Tile is the top of the range, a full tiled interior, and the most durable and the most expensive.

The finish is a surface and a measure of protection, but it is not the structure, and it rides on the shell beneath it. A finish over a sound, clean, properly prepared shell bonds and lasts. A finish over a dirty or hollow shell delaminates, and you hear it as a hollow spot underfoot before you see it fail.

The finish is troweled and then, with plaster and aggregate, it gets a start-up that cures the surface as the pool fills, covered next. The fill water and the chemistry that go with the start-up tie straight into the mechanical system in the pool and spa mechanical guide, because the same chemistry that protects a new finish is the chemistry that keeps the water clear once the pool is in service.

The plaster start-up

A new plaster or aggregate finish gets a start-up, and a botched one stains a finish that took skill to apply. As soon as the finish is troweled, the pool is filled, and the rule is to fill without stopping, in one continuous run, so the rising water does not leave a ring where it paused against fresh plaster. A garden hose with a cloth over the end, run to the bottom, fills without gouging the soft new surface.

Once the pool is full, the new finish is brushed, often twice a day for the first week or so, to knock down the plaster dust the curing surface gives off and to keep that dust from settling and etching the finish. At the same time the water chemistry is brought into balance carefully, because brand-new plaster is curing into the water and the wrong chemistry now, water that is too aggressive or too scaling, etches, stains, or clouds the finish in its first days. This is a chemistry-sensitive window, not a fill-and-forget.

The fill, the brushing schedule, and the start-up chemistry follow an established procedure, and there is more than one recognized method depending on the finish. New-plaster start-up and the water chemistry behind it run into the mechanical and water-treatment side covered in the pool and spa mechanical guide. Follow the finish manufacturer's start-up procedure and confirm the chemistry targets, because the finish is committed the moment the water comes up and a stain set in the first week is permanent.

The commercial pool code

A commercial pool answers to the health department, and the rules are public-safety law, not preferences. The code reaches into the structure you build: the depth and the depth transitions, the slope of the floor and where it is allowed to change, the no-diving zones and where diving is permitted, the depth markings on the deck and the wall, the anti-entrapment drains, the perimeter deck and barriers, and the markings and signage. These are the items the health inspector checks against the adopted code before the pool opens.

Most states base their rules on the CDC's Model Aquatic Health Code (MAHC), a model code that many jurisdictions adopt or adapt, but the version and the amendments are local. Depth markings have to be placed and sized to the code, the floor slope cannot exceed the code's limit without it being a defined transition, and shallow water has to be marked no-diving. The structural side of these rules, the depths, the slopes, the marker locations, has to be built into the shell, so they belong on the layout and the steel, not added at the end.

Build the depths, the slopes, the markings, and the drains to the code from the start, because moving a depth transition or a drain after the shell is shot means demolition. The depth, slope, marking, drain, and barrier requirements are governed by the adopted health code, the MAHC where it is adopted, and the AHJ, and they connect to the mechanical and sanitation rules in the pool and spa mechanical guide. Confirm every dimension with the health department before you pour, not after.

The circulation system is a separate trade

The circulation, filtration, and sanitation system, the pump, the filter, the heater, the chemical feed, and the controls, is a separate trade from the structure, and it is covered in its own guide. The shell job builds the rough into the structure: the main-drain sumps, the return penetrations, the skimmer or gutter pockets, and the lines, all set and pressure-tested before the shell encases them. The equipment that those lines run to sits on an equipment pad, usually outside the pool, plumbed and wired by the mechanical and electrical trades.

The two sides have to agree at the boundary. The structure has to put the penetrations where the mechanical design needs them, sized and located to the mechanical drawings, because once the shell is shot, the rough is fixed. The turnover, the hydraulics, the pump and filter sizing, the chemistry, and the anti-entrapment system design are the mechanical trade's work, detailed in the pool and spa mechanical guide.

Keep the responsibilities clear and the coordination tight. The structure team owns getting the rough placed, tied, and tested before the shell; the mechanical team owns the system those lines serve. Coordinate the penetrations by the mechanical drawings before the steel inspection, and confirm the boundary against the contract documents.

The inspections that gate the job

A commercial pool clears several inspections, and they gate the build at the points where work is about to be buried or finished. The structural steel is inspected before the shotcrete, while the cage, the cover, and the bond-beam reinforcement are still visible, because nobody can verify the steel once the shell is shot. The plumbing is pressure-tested and often inspected at the same stage, under pressure, so the lines are proven before the concrete encases them.

After the shell, the work moves to the bond beam, the tile-and-coping line, and the deck, each checked against the drawings and the code as it is built. The health department inspects the depth markings, the slopes, the anti-entrapment drains, the deck, and the barriers, and a final inspection before opening confirms the pool meets the adopted code with everything in service. On a commercial job the electrical bonding and GFCI get their own inspection, covered on the mechanical side.

Treat the pre-shotcrete steel-and-plumbing inspection as the one that cannot slip, because everything it covers disappears under concrete. Line up the inspections in the build sequence, hold the shoot until the steel and plumbing pass, and confirm the inspection requirements and the holds with the AHJ. The exact inspections and their order are set by the adopted code and the jurisdiction.

What to document

A pool is a buried structure, so the record is how you prove what is under the concrete and the deck. Capture the engineer's stamped design, the soil report, the steel as tied, the plumbing pressure test, the shell placement and cure, the finish and its start-up, and the health inspection, because once the shell is shot and the deck is poured, the record is the only way back to what is inside. A field tool like FieldOS keeps the photos, the test results, and the sign-offs tied to the job instead of scattered across phones and trucks.

The pressure-test result and the pre-shotcrete steel photos are the two records you will want most, because they are the proof that the buried plumbing held and the buried steel was right when the shell went over them.

Common mistakes

• No hydrostatic relief valve, so the empty pool floats out of the ground when the water table comes up.
• Voids and sand pockets in the shotcrete shell behind the steel, where the shell leaks and the rebar rusts.
• Plumbing not pressure-tested before the shell, so a buried leak turns into a jackhammer repair.
• Non-compliant main drains that fail the VGB Act and can trap and drown a swimmer.
• No structural or geotechnical engineer, building a structure by feel that the soil and the water loads then crack.
• Steel lying on the dirt or pushed to one face with no cover, so the bar rusts and the section is thin where it counts.
• A botched plaster start-up, filling with stops or skipping the brushing and chemistry, that stains a new finish in its first week.

Field checklist

Standards and references

The structure starts with the engineer. A structural or geotechnical engineer of record designs the shell for the water loads, the soil, the bearing, the hydrostatic uplift, and the relief, and the stamped design and the soil report control the structural work. Pool concrete design also draws on ACI guidance for liquid-tight concrete structures, and the contract documents and the engineer govern the steel, the thickness, and the details.

The shotcrete itself answers to ACI Committee 506, which publishes the shotcrete guidance, including guidance specific to shotcrete in pool construction, and to the project specification for the mix, the strength, and the acceptance. The shotcrete placement, the nozzleman qualification, and the test panels are covered in the shotcrete and gunite guide. The shell is only the structure the design intends if it is shot to that standard, void-free and cured.

The safety side is federal and health-code law. The main drains fall under the Virginia Graeme Baker Pool and Spa Safety Act and the ANSI/ASME A112.19.8 drain-cover standard, with SVRS devices to the applicable standard where required, and the anti-entrapment system ties into the mechanical design in the pool and spa mechanical guide. The depth, the markings, the slopes, the deck, and the operation are governed by the adopted health code, the CDC Model Aquatic Health Code where a jurisdiction adopts it, and the AHJ. Three things carry the whole job: a pool is an engineered structure with hydrostatic relief or it floats, you shoot a void-free shell and pressure-test the plumbing first, and you build in VGB drains and meet the pool code. The adopted code edition, the local amendments, and the engineer of record control the specifics, so confirm them on the project.

Terms and definitions

Pool construction carries its own vocabulary, and the same shell shows up under different names across a drawing set, a spec, and a health code. These are the terms that matter on the structure side.

Shotcrete / gunite shell

The pneumatically applied, steel-reinforced concrete pool structure. Gunite is the dry-mix process, where water is added at the nozzle; pool shotcrete usually means the wet-mix process, batched with water and pumped.

Hydrostatic relief valve / uplift

Hydrostatic uplift is groundwater pressure pushing up under an empty shell; the relief valve, in the main-drain sump over gravel, lets that water into the pool to equalize so the shell does not float.

Rebar cage / bond beam

The cage is the tied grid of reinforcing bar that gives the shell its tensile strength; the bond beam is the thickened, extra-reinforced top perimeter that carries the tile, coping, and deck edge and ties the walls together.

Plumbing rough

The main drains, returns, skimmers or gutter, and supply lines set and pressure-tested before the shell, so the shotcrete encases them in the structure.

VGB anti-entrapment drains

Main drains built to the Virginia Graeme Baker Act: compliant covers to ANSI/ASME A112.19.8, dual drains spaced so one body cannot block both, and an SVRS or other secondary system where required.

Plaster start-up

The procedure for a new plaster or aggregate finish: a continuous fill, frequent brushing, and careful chemistry through the first days so the curing surface does not stain or etch.

Waterline tile / coping

The tile band set at the water level on the bond beam, and the coping cap on the pool edge that sheds water away and transitions to the deck across an expansion joint.

MAHC

The CDC Model Aquatic Health Code, a model code many jurisdictions adopt or adapt for commercial pool depth, markings, slopes, drains, decks, and operation.

Related tools

Calculators and readiness checks for this work

Compare your options

FAQ

People also ask

• What is shotcrete?
• What is pool turnover rate?
• Why do bridge decks deteriorate faster than the rest of the bridge?
• Why does commercial flooring need a slab moisture test?
• What is the difference between mortar and grout in a block wall?