Custom Fibreglass VS Drop-Ins Vs Concrete Pools: What’s the Difference?

Our Stories
Written By Kim Manunui

Planning a new pool? One of the most important decisions you'll make is the type of pool construction. The three most common options in New Zealand are custom fibreglass pools, drop-in fibreglass pools, and concrete pools. While each has its benefits, understanding the key differences will help you choose the right fit for your home, timeline, and budget.

What Is a Custom Fibreglass Pool?

A custom fibreglass pool is a site-specific pool built using fibreglass technology, but without relying on a pre-moulded shell. Mayfair Pools is a pioneer in this space, handcrafting pools in place to suit your exact design, layout, and landscaping – and hence often chosen for complex or high-end designs. This allows for complete freedom in size, shape, depth, steps, and colour, while still enjoying the benefits of fibreglass.

What Is a Drop-In Fibreglass Pool?

Also known as a pre-moulded or factory-made fibreglass pool, a drop-in pool is manufactured off-site in a set shape and size, then delivered and installed into an excavated area. While fast and cost-effective, they come with limitations in design flexibility, access issues for delivery, and restricted customisation.

What Is a Concrete Pool?

Concrete pools are built on site using steel-reinforced concrete. Similar to Mayfair’s custom fibreglass, concrete pools are flexible in terms of shape and style and suitable for complex or high-end designs. However, they also come with longer build times, higher and more frequent maintenance needs, risk of cracking due to ground shifting, flooding or earthquakes, and greater long-term costs.

Comparison: Custom Fibreglass vs Drop-In Fibreglass vs Concrete

A custom fibreglass pool can be built anywhere, any size or shape. Perfect to maximise that awkward and under-used corner of your garden as in this example.

1. Design Flexibility

  • Custom Fibreglass: Highly flexible; fully tailored to your site and preferences. Can be built to any size, shape, or other specification. (Perfect for that awkward and under-used corner of your garden). Many colour options.

  • Drop-In Fibreglass: Limited to pre-made shapes and sizes. Some step and colour options available.

  • Concrete: Highly flexible; can be built to virtually any shape or specification.

2. Installation Time

  • Custom Fibreglass: Fast

  • Drop-In Fibreglass: Very fast

  • Concrete: Longest build time

3. Site Access

  • Custom Fibreglass: Built on site. Ideal for hilly sites or those with limited or tricky access. Can be built in-ground, partially or fully above-ground, and even cantilevered over an obstacle or into the air off a balcony. (Want to know more? View our article that explains the difference between in-ground, partially above-ground, and above-ground pools here).

  • Drop-In Fibreglass: Requires clear access for crane delivery of the shell, which may not suit all properties.

  • Concrete: Built on site, but may still require heavy equipment and easy access.

A stunning infinity pool built partially aboveground on a hillside against this architecturally designed home.

4. Finish & Appearance

  • Custom Fibreglass: Smooth, durable finish with premium gelcoat colours and integrated features such as lights and water features. (View Mayfair’s custom NZ-inspired colours here).

  • Drop-In Fibreglass: Similar surface finish to Mayfair, but often fewer colour choices and less flexibility in integrated design elements like lights and water features.

  • Concrete: Can be tiled or rendered; finish is highly customisable but requires more ongoing care.

5. Maintenance & Longevity

  • Custom Fibreglass: Low maintenance, non-porous surface resists algae and reduces chemical use.

  • Drop-In Fibreglass: Also low maintenance, but limited shell sizes may not optimise water circulation.

  • Concrete: Porous surface requires more frequent cleaning and resurfacing every 10–15 years.

6. Cost Over Time

  • Custom Fibreglass: Excellent long-term value with minimal maintenance and strong durability.

  • Drop-In Fibreglass: Lower upfront cost, but may compromise on design flexibility or site suitability.

  • Concrete: Highest long-term costs due to maintenance, chemicals, and resurfacing.

Why choose a custom fibreglass pool?

Mayfair’s custom fibreglass pool offer the best of both worlds: the flexibility in design and stability of concrete with the durability and low maintenance of fibreglass – plus the addition of Mayfair’s proprietary insulation.

Mayfair Pools builds each pool to fit the unique characteristics of your landscape and vision, with colour finishes inspired by New Zealand’s most iconic locations — from the bright whites of Cathedral Cove to the deep greens of Te Waihou Spring.

You’re not limited by standard shapes or shell delivery. Every element — steps, swim-outs, ledges, depths, curves — is designed for your space and lifestyle.

Drop-In vs Custom: Not All Fibreglass Pools Are Equal

It’s important to understand that not all fibreglass pools offer the same flexibility. Drop-in pools may suit some homeowners looking for a quick, standard install. But if you want a design that truly fits your site and reflects your vision, custom fibreglass is a smarter investment.

This stunning family pool features a separated paddling area for small children and an inbuilt spa pool.

Let’s Build Something Beautiful

At Mayfair Pools & Spas we’ve been building award-winning pools across New Zealand for over 50 years. Our custom fibreglass pools offer unmatched flexibility, lasting quality, and natural beauty that sets your backyard apart; built for a lifetime of memories.

View our Recent Projects page for our latest pool builds and filter by pool shape, use, colour and more.

Book a free consultation with your local Mayfair pool builder, and discover the difference a custom build can make.

Kim Manunui

Hi, I’m Kim and I work with a great team to help individuals, as well as small and not so small businesses get their message, product and services to the world using digital media and creating wonderful websites that don’t cost the earth.

I was born in Canada, and grew up around Vancouver and the mountains of British Columbia. My love of pristine environments led me to New Zealand and eventually to the mountains, lakes and rivers of the central North Island which is home. My family’s heritage is here, and it’s from here that Korio traverses the planet.

The digital world is never static and neither are we.

And I say ‘we’ because I work with an awesome group of talented people who I gather together as required to complete a project.  Whatever your business, not-for-profit or individual needs are we gather the best team to get the job done.

Collaboratively we are creative, share sustainable values and work hard for great outcomes because that’s the buzz of satisfaction that drives us.

If you have an audience and market to reach, we can make that happen. Creative design, words that work and smart behind the scenes stuff that cuts through the online noise. We’ll design your website and then build it. We’ll manage the content as well as all your hosting needs. We can handle your online advertising so you get noticed,
and we’ll manage your social media presence so you get the clicks, likes and engagement to grow your business. All within the budget you set, because none of this needs to cost the earth.  And the job doesn’t stop when your website goes live. We are your virtual business partner.

https://www.korio.co.nz
Next

From strength to strength: 25 wins at the 2025 NZ SPASA Awards