The 12 Questions That Reveal a Good Fiberglass Pool Installer

Correct answer:

Clean crushed stone (#57 or #8), typically 4–6 inches thick, but more based on soil conditions.

🚩 Red flag answers:

• Sand
• Native soil
• Whatever is in the ground

Good installers will say something like:

• Laser level / transit
• Hand screeding
• Multiple level checks before setting shell

🚩 Red flag answers:

“Eyeballing it” or using only a carpenter’s level.

Proper process usually includes:

• Plate compactor
• Rake and screed leveling
• Final laser check

Some installers compact lightly, others rely on angular stone locking—but they should have a clear explanation.

Correct materials:

• Clean crushed stone
• Pea gravel

🚩 Major red flag:

• Excavated dirt
• Clay soil
• Sand

These trap water and cause settling.

Correct method:

1. Add 12–18 inches of water
2. Add 12–18 inches of backfill
3. Repeat until full

This equalizes pressure on the shell.

🚩 Red flag:

“We backfill first and fill later or we fill the pool first and backfill later.”

Good installers may mention:

• French drains
• Perimeter drainage pipe
• Sump pit with pump; automated pump preferred
• Hydrostatic relief valve

This is especially important in Midwest clay soils where the excavated soil often weighs more than the fiberglass pool and the water. Also consider your hardscape and the impact on water formation around the pool.

Look for answers like:

• Laser level checks during placement
• Measuring waterline elevation
• Adjust stone under shell before backfill.

Your fiberglass pool is a monolithic structure and balance is important, otherwise it places stress on the shell. Even 1 inch out of level will be noticeable and place stress on the pool shell.

Steps and benches need extra support underneath.

Good installers may say:

• Hand-packed gravel
• Structural foam
• Additional stone fill

🚩 Bad installers sometimes leave voids under steps.

Professional installations:

• Pressure test lines before backfilling
• Use Schedule 40 PVC

🚩 Red flag:

“No, we’ve never needed to.” We use flexible pipe…rigid PVC is unnecessary.

Experienced installers describe a clear sequence:

1. Excavation final check
2. Stone base leveling
3. Crane sets shell
4. Level verification
5. Begin water fill
6. Begin backfill

If they can’t clearly describe this, it’s concerning.

Typical answer:

• 1 year

Pool shell warranties are much longer but with many caveats.

With respect to workmanship, consider asking for a 2-year warranty. They may require that they provide service during those years to ensure proper opening, closing and water maintenance.

This is a powerful question.

Look for:

• Level waterline
• Deck cracks
• Pool settling
• Coping separation

Pools look great when new. Problems show up after a few seasons.