How a Pool Gets Built, Start to Finish: Nine Stages, Four Inspections, and What Each One Freezes

This guide is the order. Pool School has more than a dozen guides covering the individual decisions in a pool build — shell type, finish, tile, deck, cage, water features, fire features, in-pool seating. Every one answers what to pick. None of them answers when you have to have picked it, and that is the question that actually costs money.

A pool build is not a project with a punch list. It is a sequence of one-way doors. The shell is sprayed once and every depth inside it is permanent from that afternoon. The deck is poured over a safety system that can never be looked at again. The interior finish starts a 28-day clock the moment it goes on. Nobody hands you the list of which door closes when, so here it is.

The nine stages, and what each one takes away

Durations are typical for a residential gunite pool and vary with region, weather and site.

Total: three to six months. Note where the calendar actually goes. Design and permitting can eat 5 to 12 weeks before a shovel moves, while the shell that everyone thinks of as “building the pool” is sprayed in a single day. Most overruns land in the first half, and most of them are discovered during excavation: rock, caliche, old irrigation lines, buried utility conduit, tree roots.

The four inspections, and the two that matter

The standard sequence is pre-gunite, pre-deck, pre-plaster, final. Those four names come off a county inspection checklist, and they are the only scheduled moments in the whole build when a third party looks at the work.

One honest caveat about that checklist. The publicly posted form we worked from is Marin County’s, and it is a commercial pool form — it also asks for restroom paper towels, a flow meter, and daily operating logs kept for two years. The four stage names transfer to a residential build. The individual line items do not. Your jurisdiction sets your own list, and the only version that binds you is the one attached to your permit.

Two of the four are worth rearranging your day for.

Pre-gunite: the last look at everything that will be inside concrete

At this inspection the hole is dug, the rebar is tied, and every pipe is lying in the open. What gets verified against the approved plan is pipe sizes, the number and location of main drains, skimmers and returns, and the step and bench geometry. Tomorrow it is all inside the shell.

This is the inspection to attend, because it is the last day the answers to these questions are visible:

• Are the returns where you thought, and are they deep enough below the waterline?
• Is the shallow end the depth you agreed, measured with a tape rather than assumed?
• Is the tanning ledge the depth you specified — and did you specify it as ledge depth or water depth? Those differ by about three inches, and the industry publishes both. That distinction has its own guide: sun shelf vs bench vs bump-out.
• Are the steps where you want them, at the height you want? Riser height and tread depth are quoted from inverted vocabularies by different sources — see the concrete you pour once.
• Is the plumbing pressure gauge still holding?

Pre-deck: the last look at a safety system you will never see again

Before the deck is poured, an inspector verifies the equipotential bonding grid. This is the part of a pool build homeowners understand least and can most easily confirm themselves, because it is a bare copper wire and you can simply look at it.

NEC Article 680.26(B) requires:

• a minimum #8 AWG solid copper conductor,
• forming a grid three feet around the pool perimeter,
• joined with listed bonding clamps or pressure connectors,
• attached to the pool’s reinforcing steel at a minimum of four uniformly spaced points.

Everything conductive that a swimmer could touch joins that network: the rebar in the shell, the rebar in the deck, ladders, handrails, diving board supports, metal fittings, light niches, pumps, heaters, junction boxes, metal piping, and the water itself.

Bonding is not grounding. Grounding gives fault current a safe way back to the electrical system. Bonding holds everything at the same potential so a voltage difference never develops between two things a person can touch at once. Neither replaces the other.

Two facts that routinely get misread as errors:

1. The bonding conductor is not required to run to your panel, service equipment or a grounding electrode. A bonding grid that connects to nothing at the house is not a mistake.
2. The grid is required whatever the deck is made of — pavers, or plain grass up to the coping. Electricity does not distinguish.

Once concrete covers those clamps they cannot be visually inspected again. That is the entire reason this inspection exists, and it is why a photograph of the copper loop and its four connections, taken by you and dated, is worth more than it looks.

The numbers that do not agree

Three of the figures that decide build quality are published differently by different authorities. Where an industry has no single standard, the number belongs in your contract.

The plumbing pressure test — no standard exists

Here is what is actually in circulation:

Those are not the same test. A line can pass fifteen minutes and fail overnight, which is precisely how a slow leak behaves. No published standard settles it, so this is a contract term, not a fact.

The rule: get the PSI and the duration in writing before pre-gunite, and look at the gauge yourself both when it goes on and when it comes off. Many builders leave the lines pressurised for the remainder of the build, so a dropped gauge is visible at a glance — if yours does that, it is a good sign and it gives you a five-second check on every site visit. The asymmetry is the argument: a leak found now is a repair, a leak found after gunite and decking is demolition.

The shell cure — 7 to 14 days, wet

Gunite is sprayed in a day and then wants 7 to 14 days of curing, kept damp. A shell that dries too fast before hydration completes develops micro-fractures. This is a phase where schedule pressure and quality point in opposite directions, and it is invisible in the finished product.

The startup alkalinity target — the published card contradicts itself

The National Plasterers Council’s start-up procedure is the industry protocol, and on the version published by National Pool Tile the first day instructs adjusting alkalinity to 80 ppm (whether it is high or low), while the second day opens by referring to the alkalinity having been “adjusted to 70 ppm.” Both numbers are on the same card. We are recording the discrepancy rather than picking a winner; if you are running your own startup, follow the printable card your finish manufacturer supplies and ask which figure they intend. For the underlying chemistry, our new pool startup guide and water balance and LSI cover the targets properly.

The 28 days after it looks finished

The pool is full, it is blue, and it is the least finished it will ever look again. About 86 percent of the cement in a new plaster finish cures in the first 28 days, and what happens in that window decides how long the finish lasts.

Fill day. Fill to the middle of the skimmer without stopping, as rapidly as clean drinkable water allows — 18 to 36 hours is typical. Stopping leaves a permanent ring at the waterline where you stopped. Soften the impact with a clean cloth on the hose end, or float the end on a water bottle, and put the hose in the deepest part. No people, no pets — a new finish takes footprints. Start filtration as soon as the water reaches the skimmer.

The exclusion list, all 28 days:

And the thing you should be doing: brush the entire surface, from the top of the walls down, shallow end to deep end, at least twice a day. It is manual, unglamorous, and it is the single highest-value thing an owner can do for a finish they just paid for.

One more if you chose pebble. Pebble finishes take an acid wash roughly 28 days after fill to open up the surface and clear cement haze, so a pebble pool waits a little longer before the first swim than a plaster one. Which pebble, and how the tiers translate between manufacturers, is in Diamond Brite vs PebbleTec and StoneScapes vs PebbleTec.

The decision calendar

Every construction guide we publish, placed at the stage where its decision closes. Read them in this order and you will never be the owner deciding something the week after it became permanent.

The rules, in one list

1. Make the concrete decisions first. Steps, benches, shelf depth and water features close at gunite. Tile and coping colour stay open for weeks. Most owners do this backwards.
2. Specify depths from the water surface, not the ledge or the floor, and write two numbers on the plan. The industry publishes from three different datums.
3. Get the pressure test in the contract as a PSI and a duration. There is no standard to fall back on.
4. Be there the day before pre-gunite, with the plan and a tape measure.
5. Be there the day before pre-deck, and photograph the copper bonding loop and its connections to the steel.
6. Do not let the shell cure dry. 7 to 14 days, kept damp.
7. Do not stop the fill. A pause leaves a permanent ring.
8. Nothing with wheels in the pool for 28 days, and no salt for 28 days.
9. Heater off until the plaster dust is gone, typically day 4 to 10.
10. Brush twice a day for 28 days. It is the cheapest thing on this list and it matters most.
11. Photograph everything that is about to be covered, and date it. Open plumbing and a bonding grid are the two that are worth real money later.