How to Replace a Concrete, Gunite or Vinyl Pool With Fiberglass
Swapping an old concrete, gunite or vinyl pool for fiberglass is two projects in one: taking the old pool out, then building a new one in the same yard. This guide walks through the sequence so you know what each stage involves and who does it.
Short answer: You replace an old pool with fiberglass by permitting the job, fully removing the old pool, digging a new hole sized close to the shell, preparing a stone or sand bed with drainage, setting the shell by crane, then backfilling and decking. A licensed contractor does each stage. A shell cannot sit inside an intact old pool.
What is the order of a pool replacement project?
- Choose the shell and check the site.
- Apply for permits.
- Remove the old pool.
- Excavate for the new shell and prepare the bed.
- Deliver and set the shell.
- Backfill in stages while the shell fills with water.
- Connect plumbing and equipment.
- Build the deck and restore the landscaping.
How do you choose a shell and check the site first?
Shell choice comes first because the excavation is cut to the shell, not the other way around. Our guide to fiberglass pool designs and models covers the options.
Latham’s installation guides also list what to settle before any digging starts:
- The route that equipment and the delivery truck will take into the yard.
- Underground utilities and overhead power lines.
- Setbacks from property lines, easements and house footings.
- Underground water conditions and where surface water drains.
- Local fencing rules.
These checks matter on a replacement because a fence, patio or landscaping can limit where equipment can go.
Which permits does a pool replacement need?
Latham says you will likely need a building permit to install a new pool or to remove or renovate an old one, and that rules vary by municipality. Official pages we read bear that out.
- Fairfax County, VA: a residential demolition permit covers demolition of a residential pool, and a plumbing permit is required to cap off the sewer line when the home is on public sewer. A new pool is a separate permit, and plat or grading plan requirements depend on how much ground is disturbed. Owners may apply, but the county strongly recommends that a properly licensed contractor pull the permits. See also our Fairfax County pool installation page.
- Washington, D.C.: the Department of Buildings lists swimming pools, and demolition of buildings and structures, among the projects that need a permit. Ask the department which permit type covers removing an in-ground pool.
- Maryland: counties set their own rules. Prince George’s County’s published bulletin, for example, requires a demolition permit with a dimensioned site plan, utilities terminated and a final inspection. Other counties may ask for something different.
- Virginia digging: state law requires a locate request to the utility notification center before excavation or demolition.
For every other location, including West Virginia, check with your local permit office. Ask whether the removal and the new pool are permitted together or separately, and who files each one.
How is the old pool removed?
Latham says an old pool may need to be demolished or removed completely before a new one goes in. Its installation guides describe a shell resting on a prepared bed in an excavation of its own, which is why a shell cannot sit inside or on top of an intact pool. We explain that in can you put a fiberglass pool over a concrete pool.
Removal is demolition work for a licensed contractor. Our guide to partial vs. full pool removal explains what each approach leaves in the ground. In Virginia, the state’s contractor regulation defines the swimming pool contractor specialty (POL) to include the removal of in-ground pools. It excludes plumbing, electrical, backflow and HVAC work, which need their own credentials.
The pool water has to go somewhere first. Prince George’s County’s bulletin says not to send it to the storm drain, and our guide to draining pools summarizes discharge rules for Fairfax County and D.C.
What differs by old pool type?
| Old pool | What comes out | What to ask |
|---|---|---|
| Concrete or gunite | The concrete shell. For a full removal, Prince George’s County’s bulletin calls for the material to go to a licensed disposal or recycling facility. | Whether any concrete will stay in the ground, where the debris goes, and how the floor is dealt with so water can drain. |
| Vinyl liner | The liner and the wall panels. Latham makes these walls in galvanized steel or polymer. | What is under the liner and around the walls, and where it goes. |
How much work each removal takes depends on the pool, so ask each contractor to describe the work for yours. Pool equipment and piping also come out. That bulletin lists the filter, heater and piping.
What happens at the excavation?
Latham’s Astoria and Corinthian 12 installation guides cover this stage closely.
- Size. The hole is dug very close to the shell’s size, with little disturbance to the undisturbed soil that supports it. Latham warns that a hole that is too large needs extra backfill, which can lead to settling or bulging if handled badly.
- Bed. The base is clean, crushed stone or sand, compacted. Latham says never to use excavated soil as fill.
- Drainage. Water should always drain away from the pool. The guides call for a sump pipe, or a gravity-fed daylight drain, so groundwater around the shell can be checked and managed.
- Soil. Latham’s timeline article says unstable soil may need to be built up before the shell is set.
An old pool’s hole is not automatically a good hole for a new shell. Ask your contractor how the excavation will be sized, what happens to the disturbed ground around it, and where the drain outlet will be.
How is the shell delivered and set?
Latham’s guides recommend a crane with four 20-foot straps to set the shell. They say a track excavator can be used in some cases, after getting directions from Latham. Delivery is meant to be coordinated with the finished excavation. Latham also tells crews to follow OSHA and ASME standards for the lift. Once the shell is down, it is checked for level and lifted and reset until it sits firmly on the bed.
How do backfill, plumbing and decking work?
Backfilling and filling the shell with water go together. Latham’s guides describe packing the curved areas where wall meets floor first, then adding water and backfill in alternating stages so pressure stays balanced on both sides of the wall. Latham says poorly packed curves can lead to hairline or structural cracks.
Plumbing follows Latham’s design guidance and the ANSI/APSP-7 suction entrapment standard, and local codes may require pressure testing. The deck is built around the shell, and Latham’s guide has it sloped so surface water runs away from the pool. Latham states it is not responsible for deck work. The full installation page lists these stages.
How long does a replacement take?
It depends. Latham’s timeline article gives durations for installation stages only: up to three days to excavate and set the shell, and one to four days for backfill and water. It says weather, pool size and equipment can change the total. It gives nothing for permits or for removing an old pool. Ask any contractor for a written schedule that covers each stage, including permit time.
Who does the work?
Licensed contractors do all of it. Latham’s warranty covers pools installed by a builder it has authorized, or by a licensed contractor who has complied with local building codes, the ANSI/APSP-5 standard, Latham’s owner’s manual and Latham’s approved installation procedures. It excludes failures from improper installation. Calm Water Pools coordinates removal and replacement; see our removal and replacement page.
Questions to ask any contractor
- Who files the removal permit and the new-pool permit, and when?
- Is the old pool removed completely? What stays in the ground?
- Where do the debris and the pool water go?
- How will the new excavation be sized, and how will groundwater be handled?
- How will the shell reach the yard, and what gets moved to make room?
- Will the work follow Latham’s written installation procedures?
- Can I see your license number and a written schedule?
Last reviewed October 2026 by Calm Water Pools.
Related guides
- How long pool removal takes, and the best season
- How to verify a pool removal contractor
- Partial vs full pool removal
- What affects the cost of removing an inground pool
- Can you put a fiberglass pool over a concrete pool?
- Fiberglass vs concrete pools
- Fiberglass pools FAQ
Thinking about removing or replacing an old pool in Maryland, D.C., Northern Virginia or West Virginia? See how Calm Water Pools coordinates removal and replacement or call 240-372-4440.