Greenhouse Replacement Glass: A UK Reglazing Guide
Greenhouse replacement glass is straightforward once you know your clip type and pane size. Most aluminium greenhouses use 610mm-wide horticultural glass held by spring or W clips. You can swap a single pane in under 30 minutes. Toughened glass and twin-wall polycarbonate are safer, shatter-resistant upgrades. After 16 years reglazing UK greenhouses, our advice is simple: measure twice, wear gloves, and never reuse a cracked pane.
Key Takeaways
- Identify the clip first: spring clips, W clips, Z clips and bar capping each hold glass differently and decide what you buy.
- Measure the aperture, not the old pane: a chipped pane reads short. Most panes are 610mm wide, but every brand varies.
- Four glazing choices: 3mm horticultural glass, 4mm toughened, 4mm twin-wall and 6mm twin-wall polycarbonate.
- Toughened glass is the safe swap: it breaks into blunt granules, not the long shards of horticultural glass.
- Cost per pane is low: a single horticultural pane costs a few pounds; a 5-panel acrylic pack runs about £89.
- Work top-down: always reglaze from the roof down so finished panes are not disturbed.
Installer's Note
I have reglazed greenhouses from every brand we sell, and the same mistake comes up again and again. People order glass before they check how the old pane was held in. They end up with the right size of glass and the wrong fixings, so nothing clips home. Before you measure a single pane, look closely at the frame. Is the glass held by little stainless spring clips, by W-shaped wires, by Z clips, or by a strip of aluminium bar capping screwed over the top? That one check decides everything else. I keep a labelled bag of each clip type in the van so I am never caught out on a job.
How is greenhouse glass held in place?
Greenhouse glass is not glued or sealed. It sits in a channel in the aluminium frame and is held by small metal clips or a capping strip. Four systems cover almost every UK greenhouse.
Spring clips. Small stainless steel clips that hook over the glazing bar and press against the glass edge. Common on Vitavia, Halls and many aluminium models. They flex, so a pane can be sprung in and out without tools.
W clips (and Z clips). Wire clips bent into a W or Z shape. They locate the glass sideways in the bar and stop it sliding. Often used alongside spring clips, one holding the pane down, the other holding it sideways.
Bar capping. A strip of aluminium screwed over the glass along each bar, clamping the pane from above. Found on heavier and professional ranges like Elite. It gives the firmest hold and the best weather seal, but you remove screws to take a pane out.
Rubber glazing strip. A continuous rubber seal that cushions the glass in the channel and stops rattle. It perishes over years and is worth replacing while a pane is out.
Matt's Installation Tip
Take a clip to the bench before you order. Clips look similar in photos but vary by a millimetre or two between brands, and the wrong one will not grip. Pop one spring clip and one W clip off the frame, lay them on a white surface, and photograph them next to a ruler. Match that against the spare you buy. We keep Elite, Vitavia and Halls clips in stock precisely because they are not interchangeable. A £3 bag of the wrong clips is the most common reglazing return we see.
How to measure for replacement glass
Accurate measuring is the difference between a pane that drops in and one that cracks under strain or rattles loose. The rule is to measure the aperture, not the broken pane.
A cracked or chipped pane has often lost a sliver of glass, so it reads short. Instead, measure the opening in the frame: the gap between the glazing bars, top to bottom and side to side. Then deduct a small clearance, usually 2-3mm each way, so the glass slides in without binding.
Most aluminium greenhouses use a standard pane 610mm (2ft) wide, which is why a generic 610mm replacement fits so many models. Heights vary far more, so always measure your own frame. Our greenhouse glazing options guide sets out which glazing each brand uses as standard, which helps you confirm the right thickness before you order.
| Measurement | What to Measure | Clearance to Deduct |
|---|---|---|
| Width | Gap between the two vertical glazing bars | 2-3mm total |
| Height | Channel depth top to bottom of the opening | 2-3mm total |
| Thickness | Edge of the old pane with a vernier or ruler | Match exactly (3mm or 4mm) |
| Quantity | Count every cracked, lost or scratched pane | Add 1-2 spares for breakage |
Which brands use non-standard glass sizes?
The 610mm width is common, but it is not universal. Knowing the exceptions saves a wasted order. This is where buying from a specialist who fits these greenhouses pays off.
- Vitavia and Halls: mostly 610mm-wide panes in horticultural or toughened glass. The generic 610mm replacement fits most of their popular models.
- Elite: heavier frames with bar capping, and several models run wider panes than 610mm. Always measure rather than assume, and order Elite-specific capping and clips.
- Dwarf-wall and curved-eave models: these often have shaped or part-height panes at the eaves and gable. Those panes are not standard and usually come from the manufacturer.
- Lean-to and porch sections: frequently use half-height panes along the back wall. Measure each row separately, as they are rarely all the same.
- Older or bespoke greenhouses: cedar-framed and heritage models can use sizes no longer made. For these, a sheet of glass cut to your measurement by a local glazier is often the only route.
If you tell us your greenhouse brand, model and pane size, we can confirm whether a standard 610mm pane fits or whether you need a cut-to-size sheet before you spend a penny.
Glass or polycarbonate: which replacement to choose
A broken pane is a good moment to rethink your glazing. You can replace like for like, or upgrade to something safer and warmer. Four options cover most needs.
3mm horticultural glass. The original glazing on most older greenhouses. It passes around 90% of light, the highest of any option, and is the cheapest per pane. The drawback is safety: it breaks into long, sharp shards.
4mm toughened glass. The safe upgrade. Heat-treated so it breaks into small blunt granules rather than shards. It is the sensible choice for any greenhouse near children, pets or a path. Our glass versus polycarbonate comparison covers the safety case in full.
4mm and 6mm twin-wall polycarbonate. Lightweight, shatter-resistant and warmer. Twin-wall traps a layer of air, so it holds heat better than glass and diffuses light evenly. It is the best choice for windy or exposed sites. The trade-off is slightly lower light transmission and a softer surface that scratches. Our twin-wall versus single-wall polycarbonate guide explains the thickness choice.
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Matt's Pick for a quick, safe reglazeBest For: Swapping broken glass panes on Vitavia Saturn, Vitavia Orion, Halls Supreme and Halls Silverline lean-to greenhouses. Why I Recommend It: These 610mm x 610mm acrylic panels drop straight into the standard glazing channel with no trimming. They weigh about half what glass does, so overhead panes are far easier to handle solo, and they are shatter-resistant. I reach for these on any job where safety or weight is the priority. Price: £89 for a 5-panel pack |
How to replace a greenhouse pane safely
With the right pane and clips in hand, the swap itself is quick. Pick a calm, dry day. Wind catches a loose pane and turns it into a hazard. Wear cut-resistant gloves and safety glasses throughout.
- Clear the area. Move pots and staging away from the bay you are working on. Lay an old sheet on the ground to catch glass fragments.
- Remove the broken pane. For clipped glass, unclip the spring and W clips and lift the pane out. For bar capping, unscrew the capping strip first, then lift the pane clear.
- Clean the channel. Brush out old glass splinters and grit from the glazing bar. Replace perished rubber strip now while the channel is empty.
- Fit the new pane. Slide the new glass or panel into the bottom channel first, then ease it back into the side bars. It should sit without forcing.
- Refit the clips. Hook the spring clips back over the bar against the glass, then locate the W or Z clips to stop sideways movement. For capping, screw the strip back down evenly.
- Check the seal. Press the pane gently. There should be no rattle or movement. A loose pane means a missing clip or too much clearance.
Matt's Tip: Bag the broken glass on site
Never carry broken greenhouse glass loose to the bin. I learned this the hard way years ago with a sliced thumb. Slide every shard into a thick rubble sack, wrap it, and label it as glass for the waste crew. Sweep the area twice, because slivers of horticultural glass are almost invisible on soil and gravel. A magnet will not lift glass, so a stiff brush and a dustpan are your only tools. Two minutes of tidying saves a nasty cut weeks later.
When to convert the whole greenhouse
If you are replacing more than a few panes, it can pay to reglaze the whole greenhouse rather than patch it. Mixed glazing looks untidy and ages unevenly. Three triggers tell you it is time for a full conversion.
Repeated breakages. If horticultural glass keeps cracking on an exposed site, switch the lot to toughened glass or polycarbonate and stop the cycle.
A safety concern. Once children or pets use the garden, a full move to toughened or polycarbonate removes the shard risk entirely. This is the most common reason our customers convert.
Heat loss. If you heat the greenhouse in winter, twin-wall polycarbonate cuts the running cost by holding more warmth than single glass. Keeping that heat in pairs well with good summer shading, which our greenhouse cooling guide covers for the other end of the year.
You will find replacement glass, acrylic panels, spring clips, W clips and glazing rubber in our greenhouse replacement glass and spares range, and full sheets in the toughened glass and polycarbonate sections. For clips and fixings, these are the parts our installers fit most:
Replacement glazing and fixings
If you are not sure which clip or pane fits your model, the team at Greenhouse Stores can match it from your greenhouse brand and size. We stock the spares because we fit them every week.
Cost of replacing greenhouse glass
Reglazing is one of the cheapest greenhouse repairs. The glass itself is inexpensive; the cost is mostly your time. Here is what to budget.
| Item | Typical Cost | Best For | Matt's Verdict |
|---|---|---|---|
| 3mm horticultural glass pane | A few pounds per pane | Like-for-like repair, max light | Cheapest, but sharp if it breaks |
| Acrylic panel 5-pack | £89 | Vitavia and Halls, safe and light | My pick: drops in, half the weight |
| 4mm toughened pane | Mid-range per pane | Family gardens, safety | The sensible safe upgrade |
| Spring or W clips (50 pack) | £26 | Re-securing any clipped glass | Buy the brand-correct clip |
| Glazing rubber (10m) | £22 | Stopping rattle and draughts | Replace while the pane is out |
"Reglazing scares people more than it should. The job is quick once you know your clip type and measure the aperture rather than the broken pane. In 16 years I have never met a greenhouse I could not reglaze in an afternoon. The only jobs that go wrong are the ones where someone guessed the clip or the size. Take a clip to the bench, measure the gap, and order once."
— Matt W, Greenhouse Stores
Frequently asked questions
What size is greenhouse replacement glass?
Most aluminium greenhouse panes are 610mm (2ft) wide, but heights vary by model. The 610mm width is a near-standard across Vitavia, Halls and many other brands, which is why generic panes fit so many greenhouses. Always measure the aperture in your own frame for height, and deduct 2-3mm clearance so the pane slides in without binding.
Can I replace greenhouse glass with polycarbonate?
Yes, you can replace glass with twin-wall polycarbonate in the same frame. Polycarbonate is lighter, shatter-resistant and warmer, making it ideal for exposed or family gardens. Check the channel depth takes the panel thickness, usually 4mm or 6mm, and use the correct clips. The only trade-offs are slightly lower light transmission and a surface that scratches more easily than glass.
How do I measure a greenhouse pane for replacement?
Measure the aperture between the glazing bars, not the broken pane. A cracked pane has usually lost a sliver, so it reads short. Measure the opening top to bottom and side to side, then deduct 2-3mm each way for clearance. Match the thickness, 3mm or 4mm, to the existing glass exactly.
What holds greenhouse glass in place?
Small metal clips or an aluminium capping strip hold greenhouse glass in place. Most aluminium greenhouses use stainless spring clips with W or Z clips to stop sideways movement. Heavier ranges like Elite use bar capping screwed over the glass. Identify which system your greenhouse uses before ordering, because clips are not interchangeable between brands.
Is toughened glass worth it for a greenhouse?
Yes, toughened glass is worth it for safety in most gardens. It breaks into small blunt granules rather than the long, sharp shards of horticultural glass. That makes it the sensible choice near children, pets or a path. It costs a little more per pane than horticultural glass but removes the main injury risk if a pane ever breaks.
How much does it cost to reglaze a greenhouse?
A single horticultural pane costs only a few pounds, so most reglazing is cheap. A 5-panel acrylic pack costs around £89, clips run about £23 to £26 for 50, and glazing rubber is around £22 for 10 metres. The main cost is your time, not materials. A full toughened-glass conversion costs more but is still far cheaper than a new greenhouse.
