It’s one of the most common questions we hear from families considering a new pool: do fibreglass pools crack? It’s a fair thing to ask. Fibreglass looks smooth and almost delicate compared to the solid heft of concrete, so it’s natural to wonder how it holds up over time. The short answer is that fibreglass pools are far more durable than most people expect, and cracking is uncommon when a pool is correctly installed and looked after. Here’s what you actually need to know.
Fibreglass vs Concrete: Which Is More Likely to Crack?
Concrete has a reputation for toughness, but it has a significant weakness: it’s strong under compression but brittle under tension. A sharp impact, a jump off the side, or even the ground shifting slightly underneath can cause concrete to chip, crack, or spall over time. Resurfacing a concrete pool is a big job and an ongoing cost. If you’d like a detailed side-by-side comparison, our fibreglass vs concrete pool guide covers it thoroughly.
Fibreglass works differently. Despite weighing up to 75% less than steel, fibreglass can match it for structural strength. The woven material used in fibreglass shells gives them a degree of flexibility that concrete simply doesn’t have, allowing the shell to absorb movement and pressure rather than fighting against it. That flexibility is actually one of fibreglass’s biggest strengths, particularly in Melbourne and the Mornington Peninsula where soil conditions and ground movement can vary considerably.
What Actually Causes a Fibreglass Pool to Crack?
Cracking in fibreglass pools is uncommon, but it does happen, and it’s almost always linked to one of three things.
Poor Installation
This is the most common cause. If the pool shell isn’t set on a properly levelled, stable base, or if the backfill isn’t done correctly, the shell can shift and stress over time. Getting the installation right from the start is what separates a pool that lasts decades from one that causes problems. At Master Pools, site preparation, precise levelling, and correct backfill are a core part of every installation, not an afterthought. We’ve completed over 2,000 fibreglass pool installations across South East Melbourne and the Mornington Peninsula, and that experience shows in how we approach every site.
Water Pressure Issues
Fibreglass pools are designed to hold water. When the pool is full, the water pushes outward against the surrounding soil, and that balance is part of what keeps the shell in shape. If the pool is drained too quickly or left empty for an extended period, the soil can push inward and the shell may distort or crack. The lesson: don’t leave your fibreglass pool empty any longer than necessary.
Surface Gel Coat Cracking
Fibreglass pools have a gel coat layer on the surface, and over many years, fine surface cracks can appear. These are sometimes called spider cracks, and they’re a cosmetic issue rather than a structural one. They don’t mean your pool is failing. They can be caused by the gel coat being applied too thinly during manufacturing, or by objects pressing against the shell from outside, such as tree roots or compacting soil. A professional can resurface the gel coat without major disruption. To learn more about the Crystallite Colour Guard surface technology that protects against this, see Aqua Technics’ pool technology page.
What to Look for in a Fibreglass Pool Shell
Not all fibreglass shells are built the same way. The quality of the shell itself makes a real difference to long-term performance. At Master Pools, we exclusively install Aqua Technics fibreglass pool shells, one of Australia’s most respected pool manufacturers. Here’s what sets their shells apart:
- Full structural ribbing runs along the sides of the pool, making the shell independently structural. It can hold its shape on its own, without relying entirely on the surrounding soil or water.
- A 200mm wide edge beam eliminates the need for a concrete ring beam or external paving work that could place stress on the shell.
- Graphene Nano-Tech reinforcement in the shell for added strength and durability.
- Crystallite Colour Guard surface finish for long-lasting colour and a non-porous, low-maintenance gel coat.
- Extended lifetime structural warranty, so if the shell were to crack due to a manufacturing fault, it’s covered.
How Does Fibreglass Hold Up in Melbourne’s Conditions?
Melbourne’s variable climate and the diverse soil types across the south-east and the Peninsula make material choice genuinely important. Fibreglass handles both ground movement and temperature fluctuation better than concrete precisely because of that built-in flexibility. It’s also worth noting that fibreglass pools retain heat more efficiently than concrete, which means less energy spent getting your pool to a comfortable temperature. If that’s relevant to you, our blog on whether fibreglass pools are warmer than concrete goes into the detail.
The Master Pools Difference
We’ve been installing fibreglass pools across South East Melbourne, Bayside, and the Mornington Peninsula since 1991, with over 2,000 pools completed. That experience matters when it comes to getting the installation right the first time. Every pool starts with thorough site preparation: clearing the area, levelling the ground precisely, and ensuring the backfill suits the specific soil conditions on your property.
You’re welcome to see what we do for yourself at our Cranbourne West display centre, Victoria’s only fully enclosed pool showroom, where you can walk around actual pool shells in operation before making any decisions. You can also explore our full fibreglass pool range and colour options online.
So, Will Your Fibreglass Pool Crack?
With quality materials, correct installation, and basic care, the honest answer is: very unlikely. Fibreglass pools are built to handle daily use across decades, and the shells we install come backed by a lifetime structural warranty for added peace of mind.
If you’d like to talk through your options or book a free site visit, get in touch with the Master Pools team. We’re happy to walk you through what’s involved and help you make the right choice for your backyard.
