Plastic & Polycarbonate Skylight Installation in Cheltenham & Gloucestershire

Not every roof needs a premium glass rooflight. For a garage, an outbuilding, a flat-roof utility space, a commercial unit or simply a project where budget matters most, a plastic or polycarbonate skylight can be the sensible, cost-effective choice. Done well, it brings in plenty of daylight at a fraction of the price of glass. Done badly, it leaks, yellows and looks tired within a few years. We install plastic and polycarbonate skylights as part of our specialist work across Cheltenham, Gloucester, Stroud, Cirencester, Tewkesbury and the Cotswolds, with the same care we give a glass unit.

This page explains what plastic and polycarbonate skylights are, when they make sense, the types and materials available, how they perform, how we install them, what they tend to cost in 2026, and how we cover Cheltenham and Gloucestershire. If you would rather just talk it through, you can get a quote at any point.

What plastic and polycarbonate skylights are

Instead of glass, these skylights use a tough, lightweight plastic glazing — most commonly polycarbonate, sometimes acrylic (often sold under names like Perspex). The most familiar form is the classic dome rooflight: a raised, often opal-white bubble of plastic sitting on a kerb on a flat roof. You will have seen them on flat-roofed extensions, schools, workshops and commercial units up and down the county.

The appeal is straightforward. Plastic glazing is far lighter than glass, very resistant to impact, simpler to handle on a roof, and considerably cheaper. For the right project, that combination is hard to beat. We cover the dedicated dome work on our dome rooflight installation page, and the budget picture on our polycarbonate skylight cost page.

When a plastic skylight makes sense

Choosing plastic over glass is about matching the product to the job and the budget. There are projects where it is clearly the right call, and projects where glass earns its higher price. Being honest about which is which is part of how we work.

Plastic and polycarbonate skylights tend to suit:

• Garages, workshops and outbuildings, where you want daylight and value without the cost of glass.
• Flat-roof utility spaces and stores, where appearance is secondary to function.
• Commercial and light-industrial units, where domes light a large floor area economically.
• Budget-led residential projects, where the priority is bringing light in for the least outlay.
• Replacing an existing dome that has yellowed, cracked or started to leak.

For a habitable room in the main house — a kitchen extension, a loft bedroom — we would usually steer you towards a glass rooflight or a VELUX window installation for the clarity, the energy performance and the long-term looks. Our guide to VELUX versus cheaper skylight alternatives sets out that trade-off plainly, so you can decide where your money is best spent.

Types and materials

There is more variety in plastic skylights than the basic dome image suggests, and the material you choose makes a real difference to clarity, longevity and cost.

Polycarbonate

The workhorse material. Polycarbonate is extremely impact-resistant — effectively unbreakable in normal use — lightweight and available in single-skin, twin-wall and multi-wall sheets. The multi-wall versions trap air between layers for better insulation. Modern polycarbonate is usually UV-protected on the weather side, which slows the yellowing that older sheets were prone to.

Acrylic

Acrylic (Perspex and similar) is clearer and glossier than polycarbonate, holding its optical quality well, but it is more brittle and less impact-resistant. It is a common choice for domes where appearance matters a little more.

Dome profiles and finishes

Domes come in clear, opal (diffusing, milky white) and tinted finishes. Opal is popular because it spreads daylight softly and hides the view of a flat roof above. They are available as fixed or opening (manual or electric) units, single-skin for outbuildings or triple-skin for better insulation where it matters.

Flat plastic rooflights

Beyond the traditional dome, low-profile flat polycarbonate rooflights offer a more contemporary look while keeping the cost and weight advantages of plastic. They suit a modern flat-roof extension where the budget will not stretch to flat glass.

How they perform

It pays to be clear-eyed about how plastic compares with glass, so you choose with your eyes open.

Light: Opal polycarbonate gives a soft, diffused daylight that fills a space evenly — excellent for a workshop or utility room, less so where you want a crisp view of the sky. Clear options give brighter, more direct light but show the roof above.

Insulation: A single-skin dome insulates poorly; a multi-wall or triple-skin unit is considerably better, though still rarely a match for energy-efficient glass. For a habitable room where warmth matters, this is the main reason we point people towards glass, and our how energy efficient skylights are page puts the comparison in context.

Longevity and yellowing: The honest answer is that older, unprotected polycarbonate did yellow over time. Modern UV-protected sheets resist it far better, but plastic will never have the indefinite clarity of glass. We cover this in full on our do polycarbonate skylights yellow page, so you know exactly what to expect from the material you choose.

Strength: This is where plastic shines. Polycarbonate shrugs off hail, falling debris and impact that would crack glass, which is part of why it is so common on commercial and industrial roofs.

Why use a specialist for a plastic skylight

A dome or polycarbonate rooflight looks simple, and that is exactly why so many are fitted poorly. The unit itself is straightforward; the kerb it sits on, and the weathering around it, are not. Most failed domes do not fail because the plastic gave out — they fail because the upstand was too low, the flashing was wrong, or the seal around the kerb was never done properly.

Because rooflights are all we fit, we treat the kerb and the weathering as the heart of the job. We build or check the upstand to the right height so water cannot back up under the unit, dress the flashing correctly into your flat-roof covering — felt, EPDM, GRP or single-ply — and seal the perimeter so the opening stays watertight for the long term. That is the difference between a dome that lasts and one you are calling someone about after the first wet winter.

How the installation works

The same calm, predictable sequence applies whether you are having a single garage dome or a run of rooflights across a commercial roof.

1. Survey and fixed quote

We look at the roof, the covering and the space below, recommend the right unit and finish for the job, and give you a fixed written quote covering the product, the work and the price.

2. Forming the opening and kerb

On the day, we protect the area below, form or adjust the opening, and build or check the upstand kerb to the correct height. On a replacement, we remove the old dome and bring the kerb and weathering up to standard at the same time.

3. Fitting and weathering the unit

The dome or rooflight is fitted and sealed onto the kerb, and the flashing is dressed properly into the roof covering. This is the part that keeps it watertight, so it is the part we never rush.

4. A clean finish

We finish the reveal inside where needed and leave the site clean, with the old unit and waste taken away. You can see the full scope of what we offer on our services page.

Building regulations and planning in the Cotswolds

For most outbuildings, garages and flat-roof extensions, a plastic or polycarbonate skylight is straightforward. Adding or replacing a rooflight usually falls under permitted development, and building regulations apply to the structural opening and, for habitable space, the thermal performance. A single-skin dome on a detached garage is rarely contentious; a rooflight serving a habitable room must meet the energy standards set out on our Part L rooflight U-value requirements page, which is one more reason multi-skin or glass tends to win for living spaces.

As ever in the Cotswolds, conservation areas and listed buildings need extra care. A prominent plastic dome on a roof slope facing a road in central Cheltenham, Winchcombe or Cirencester is unlikely to be acceptable, and a sympathetic conservation rooflight may be required instead. On a listed building, listed building consent is generally needed. We will tell you plainly where you stand, and a word with Cheltenham Borough, Cotswold District, Tewkesbury Borough or Stroud District council settles any doubt.

Indicative cost in 2026

Cost is usually the main reason people choose plastic, so here are realistic 2026 figures for a supplied-and-fitted unit in the Cheltenham and Gloucestershire area. They are indicative only — the figure that matters is the fixed written quote we give you after seeing the job.

• A standard polycarbonate dome on an existing kerb, supplied and fitted: typically £450 to £900 depending on size and skin count.
• A new dome including forming the opening and kerb: often £800 to £1,500.
• A like-for-like replacement of a yellowed or failed dome: frequently £400 to £800, as the kerb already exists.
• A flat polycarbonate rooflight on a modern extension: from £700 upwards depending on size.

Plastic is genuinely the budget-friendly route, and for the right job it is money well spent. Just be clear about the trade-offs in clarity, insulation and long-term looks — our polycarbonate skylight cost page goes into detail. Whatever the figure, you will always have a fixed price in writing before we start.

Across Cheltenham and Gloucestershire

We are based in Cheltenham and cover the town and the wider county. Plastic and polycarbonate skylights crop up everywhere — garages and workshops in Cheltenham and Gloucester, light-industrial units around Tewkesbury and Stroud, outbuildings and barns across the villages towards Cirencester, Winchcombe and Bishop’s Cleeve. We fit and replace them all, matching the unit and the weathering to the roof in front of us.

You can see the full list of places we serve on our areas we cover page. Wherever you are in Gloucestershire, the same approach applies: specialist work, a fixed written price and a finish we are happy to put our name to — even on a humble garage dome.

Why choose Aspect Skylights Cheltenham

We will give a plastic dome the same care we give a premium glass lantern, because a watertight roof opening is a watertight roof opening regardless of price. We will also be honest with you: if a glass rooflight would serve you better for the room you have in mind, we will say so rather than sell you the cheaper option for the sake of it.

You get a fixed written quote before any work begins, a tidy site cleared each day, and a written guarantee on our workmanship. Manufacturer product warranties apply on top of that, depending on the unit you choose. If a plastic or polycarbonate skylight is the right answer for your project, we would be glad to help — get a quote and we will take it from there.