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10mm Opal Polycarbonate Twinwall Roofing Sheet

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10mm Opal Marlon ST Twinwall polycarbonate sheet is a lightweight insulating glazing sheet manufactured from damage resistant polycarbonate. Light in weight but rigid in structure, Marlon ST twinwall roofing sheets and accessories offer an incredibly adaptable yet economical roofing or glazing solution.
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We have the machinery and expertise to manufacture bespoke items in acrylic, polycarbonate and many other plastics, from one-offs to large production runs. Read more about the various services we offer, or complete the form below to request a quote.

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Edge polishing is a fabrication process that polishes the edges of acrylic panels, removes any cutting marks, and achieves a smooth, glossy finish.  Read more

Rotary & Laser Engraving

Laser engraving is a fabrication process that uses a laser beam to physically remove the surface of a material to create an indentation that is noticeable to both the eye and touch.  Read more

Line Bending

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10mm Opal Marlon ST Twinwall polycarbonate sheet is a lightweight insulating glazing material manufactured from damage resistant polycarbonate. Co-extruded UV protection provides resistance against the effects of UV weathering. Light in weight but rigid in structure, polycarbonate roofing sheets used alongside the complete Marlon ST rage of fitting accessories offer an incredibly adaptable yet economical roofing or glazing solution.

Marlon ST multiwall sheets are available in a range of standard sizes but can also be supplied cut to size ready for immediate installation.

Typical applications

  • Lean-to extensions
  • Car ports
  • Conservatories
  • Pergolas
  • Gazebos
  • Sun rooms
  • Swimming pool covers
  • Rooflights
  • Canopies
  • Walkways

Key features

  • Order cut to size
  • Part of the high quality Marlon ST Range
  • Lightweight
  • Rigid
  • Hight structural strength
  • High light transmission
  • Good insulation
  • Solor control
  • Easy installation
  • UV protection

The Marlon ST Polycarbonate Roofing System

At Simply Plastics we stock and supply the Marlon ST Polycarbonate Roofing System, previously branded as Corotherm, which is manufactured in the UK by Brett Martin. The range includes all of the components required to install a fully weatherproof and waterproof roof and it used by both professional fitters and DIY'ers alike.

Image of Multiwall installation

Polycarbonate Roofing Sheet

Twinwall and Multiwall Polycarbonate sheet available in Clear, Opal and Bronze finishes in standard sheet sizes or cut to size.

Glazing Bar

Roofing Glazing Bars are fitted to rafters to support and join roofing sheets.

End Cap

Glazing Bar End Caps are fitted to the ends of glazing bars for a neat finish.

Side Flashing

Glazing Side Flashing is used to finish the side edges of the polycarbonate roofing sheet.

End Closure

The Roofing End Closure finishes the front edge of the roofing sheets.

Butyl Flashing

Butyl Wall Flashing Tape is applied where the roofing sheet meets the wall to prevent water entering the joint between the two surfaces.

Solid Tape

Solid Roofing Tape is used to cover and seal the open flutes at the end of the roofing sheets, it's specifically used to seal the end of the roofing sheet that meets the wall.

Breather Tape

Roofing Breather Tape is applied to the open edge of the bottom side of the roofing sheets. It creates a protective seal while permitting air to move freely in and out of the sheet, helping minimise condensation.


Easy to handle and install

The Marlon ST range is suitable for DIY installation. Marlon polycarbonate roofing sheets and fitting accessories are all light in weight and easy to handle. If not ordering roofing sheets cut to size twinwall polycarbonate can be cut on site using a saw with a fine toothed blade.

Cut to Size

Take advantage of our cut to size service. Order Twinwall polycarbonate sheets cut to size, delivered to your door, ready for installation.

Please note - All twinwall and mulitiwall polycarbonate sheet ordered cut to size (rather than in standard sheet sizes) are supplied with the top edge sealed with Marlon breather tape and the bottom edge sealed by Marlon solid tape. Sheeting ordered in standard sizes rather than cut to size is supplied without tape with the flutes open. Breather tape and Solid tape should be applied to the open ends during installation.

Marlon ST Range

10mm Opal Twinwall Polycarbonate Sheet is part of the Marlon ST Range. The range includes various finishes of multiwall polycarbonate sheeting plus all to fixing accessories required to complete your project.  


Light in weight but rigid and self-supporting. The twinwall stricture of the sheet creates it's rigidity, the amount of polycarbonate used to create the sheet is relatively low, keeping the weight and cost of the sheet down.

Light Transmission

Multiwall polycarbonate sheet offers excellent light transmission. Keep the elements out but let the natural light flood in. The 10mm Opal option offers 34% light transmission. The Clear and Bronze Tint finishes offer differing levels of light transmission and diffusion to suit your requirements. Cut energy costs by utilizing natural light over artificial light.


The multiwall structure of Marlon ST sheet provides a thermally insulating glazing solution. Achieve U-values as low as 0.83W/m²K

UV Protection

Marlon ST has a layer UV protection which blocks 98% of harmful UV rays. UV protective glazing protects everything underneath from the damaging effects of the sun, be it people, animals or plants.


Brett Martin


Marlon ST (Corotherm)



Sheet thickness


Rib spacing

12.5mm (Nominal)

Light transmission


Specific gravity

1.2 g/cm³

Tensile strength at yield

>60 MPa

Tensile strength at break

>70 MPa

Modulus of elasticity

>2300 MPa

Softening temperature - Vicat ‘B’


Linear thermal expansion

6.8 x 10-5 m/m.K

Maximum service temperature


Fire rating

UK Class 1



This product is dispatched directly from the manufacturer and delivered by a third-party courier, which results in a £36 delivery charge. Orders exceeding £600 qualify for free delivery. The estimated delivery period is 5 working days.

All listed prices are inclusive of VAT.

For further information on delivery, including Europe and Remote areas please see Delivery information.

Can I collect my order from Simply Plastics?

Yes, of course. Orders can be collected from our premises in Colchester, Essex. At the final stage of the checkout process there is a delivery option labelled "Collection/pickup" which is free. Once your order is complete, you will be notified by email along with our address and collection times.

I need my order urgently, can I pay for faster shipping?

Yes. We offer an express delivery service which aims to deliver all orders in 1-3 working days. Orders are delivered by a recognised courier company and may require a signature on delivery.

Is it possible to cut twinwall and multiwall myself?

Yes, the walls of twinwall and multiwall polycarbonate sheets are very thin and therefore can easily be cut with a fine toothed saw. If you do choose to cut twinwall/multiwall roofing sheets yourself you should consider sealing the openings using breather tape or solid roofing tape. 

What's the difference between twinwall and multiwall polycarbonate sheet?

Generally speaking twinwall refers to a product that has just two walls, whereas multiwall refers to any polycarbonate sheeting that has more than two walls.

We offer Marlon ST Sheet in the thicknesses and wall structures below,

10mm - Twinwall

16mm - Triplewall

25mm - x7 wall

What colour twinwall or multiwall polycarbonate sheet should I use?

We offer multiwall sheet in three finishes, Clear, Opal and Bronze. Each finish offers different benefits to suit different requirements.

Clear - High light transmission with most standard appearance

Opal - Lower light transmission provides increased privacy and heat reduction

Bronze - Reduces glare  

What thickness multiwall polycarbonate sheet should I use?

Simply Plastics offer Marlon ST Polycarbonate multiwall sheet in thickness of 10mm, 16mm and 25mm to suit different applications.

Here are some example applications to guide your decision,

10mm - Garden Pergola, Vertica privacy glazing

16mm - Gazebos, Lean-tos, Carports

25mm - Large lean-to extensions, Garden buildings

What side of Marlon ST Multiwall sheeting is UV protected?

This should be clearly labelled on the protective film.

Which direction do the flutes run on twinwall and multiwall polycarbonate roofing sheets?

The flutes run parallel to the height of a sheet.

Rated 5/5 from 2 reviews

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Excellent service and quality of materials.

Reviewed by Simon on 23 Jun, 2024 Read all
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