4mm Greenhouse Glazing Sheets & Accessories

We stock all popular greenhouse glazing sheet sizes, in packs of five or more. If you need a different size sheet please get in touch.

Options include 4mm twinwall polycarbonate glazing sheets (ideal for diffusing light), and the 4mm solid plate polycarbonate sheet (which are crystal clear and look like glass).

Note that the sheets can be trimmed to size. We recommend using either a stanley knife or fine toothed saw to trim the twinwall sheets. The solid polycarbonate sheets should only be trimmed using a fine toothed saw. 

Sheet options available

You can choose from two types of 4mm polycarbonate glazing:

4mm Twinwall Polycarbonate Sheets (ideal for light diffusion)

• Made in the UK
• Backed by a 10-year manufacturer’s warranty
• UV protected on one side
• 88% light transmission
• Lightweight, strong and impact-resistant
• Reduces heat loss
• Ideal for insulation and durability

4mm Solid Polycarbonate Greenhouse Sheets (clear plate – transparent like glass)

• • Crystal clear finish that looks like glass
  • Made in the UK
  • Backed by a 10-year manufacturer’s warranty
    UV protected on both sides

• 90% light transmission

• Around half the weight of glass, yet up to 250x stronger

• Excellent clarity with added strength and safety

Sizes & ordering

• We stock the most popular sheet sizes, available in packs of 5 sheets or more
• To reduce the risk of damage during delivery, we cannot ship fewer than 5 twinwall sheets
• If you need a custom size, please contact our office and we’ll be happy to help

Whether you’re replacing damaged panels or upgrading your greenhouse glazing, our 4mm polycarbonate sheets offer a durable, lightweight and long-lasting solution.

Comparing Twinwall & Solid Polycarbonate Sheets: 

What’s the difference between twinwall and solid polycarbonate glazing?

Twinwall polycarbonate has a hollow, double-layer structure that diffuses light and improves insulation. Solid polycarbonate is a single, clear sheet that looks like glass but is far stronger and lighter.

Which is better for a greenhouse – twinwall or solid polycarbonate? 

Twinwall polycarbonate is usually the better option for greenhouses, as it offers improved insulation and diffused light that helps protect plants – however solid polycarbonate is the better choice if clear visibility is important to you.

Are 4mm polycarbonate sheets suitable for replacing glass greenhouse panels? 

Yes. Both 4mm twinwall and solid polycarbonate sheets are commonly used as a replacement for glass. They are significantly stronger, lighter and safer than glass.

Are the sheets UV protected?

Yes. 

• Twinwall polycarbonate sheets are UV protected on one side 
• Solid polycarbonate sheets are UV protected on both sides 

This helps prevent yellowing and prolongs the lifespan of the sheets.

Why do you sell twinwall sheets in packs of 5 or more? 

To reduce the risk of damage during transit, we cannot ship fewer than 5 twinwall polycarbonate greenhouse sheets. Packaging multiple sheets together helps protect them during delivery.

Can I order custom-sized greenhouse glazing sheets? 

Yes. If you require a size that isn’t listed, please contact us and we’ll be happy to advise on availability and lead times.

Which way round should twinwall polycarbonate be installed? 

Twinwall sheets must be installed with the UV-protected side facing outward. This is marked on the protective film.