Replacing glass with plastic- how to?

Discussion in 'Greenhouse Growing' started by Selleri, Aug 7, 2025.

  1. Selleri

    Selleri Koala

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    The recent storm decided that I will now start fixing my inherited greengouse with proper stiff plastic sheets- the current "plastic and duct tape" solution will not be great over winter.

    I need four side panels and two roof ones and lots of advise- I'm a greenhouse newbie. :)

    A merchant advised me on material and thickness but also about their order fee which I refuse to pay so will look elsewhere.

    I'd be grateful for recommendations on what to buy (rolled up material is easily available on Amazon), how to cut and measure properly, and how to fix the panes?

    I have those greenhouse clippy things but am not quite sure how to go about with them.

    The door doesn't have clips, I guess suitable glue would work there?

    And any suggestions on how to replace the roof pane from inside? The greenhouse is in a corner so has no external access in there.

    This is what the merchant advised on the material:

    "The most commonly used thickness for green house panels is usually anything from 2mm - 5mm. We also recommend replacing it with the same thickness that was there previously.

    The material I would recommend using is Clear Polycarbonate as this material is over 200 times stronger than glass, is impact resistant, weather resistant and also offers UV protection.

    Please feel free to use the think below to this material.

    https://www.cutplasticsheeting.co.uk

    We currently have a minimum order charge of £50.00 ex vat."

    Thanks very much!
     
  2. CarolineL

    CarolineL Total Gardener

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    Careful what they say about "UV protection". Do they mean that the polycarb is protected from damage due to UV (it gets brittle) or that it absorbs UV and doesn't let it through - protecting the inside, but not good for plants!
    Sheet twin wall polycarb is used for conservatory roofs, and normally has a coat on one side to protect it against UV damage, which you place on the outside. Anything that rolls up is probably not robust enough. If you get sheets they are (I think) 8 by 4 feet, and can be cut to size. Since greenhouses are normally built of 2 feet wide panels, that should match. I'd cheat and use something like "Sticks like" all round the edges. It would mean you could do the roof from inside off a stepladder. That's just my idea - I use twin wall as an insulation layer inside my greenhouse, so installation is different.
     
  3. Philippa

    Philippa Gardener

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    Consider clear Acrylic rather than polycarbonate. If you can find a supplier, either local or online, they will cut the panes to the size you require.
    I found it worked well enough when I lost several roof and side panels of toughened glass on my Aluminium GH the other year.
     
  4. JWK

    JWK Gardener Staff Member

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    I've used Wickes acrylic sheet to replace some glass greenhouse panels. You buy a cheap cutting tool from wickes which scores the acrylic, then you snap it. Much easier than cutting glass. It just clips in place like glass, I have stainless steel spring clips on my greenhouse. I wouldn't use glue, if you did then don't glue at the bottom, as usually it needs that gap for rain drainage.
     
  5. ricky101

    ricky101 Total Gardener

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    As you are finding out Clear Perspex/Acrylic sheets can be very expensive.

    When faced with football breakages we opted for 10mm twin wall polycarb sheets which you can buy from places like Wickes off the shelf or mail order from places like this which cut to size.
    Polycarbonate Products | The Polycarbonate Store

    You can get greenhouse sized 4mm twinwall polycarb sheets quiet cheaply.

    Though twinwall still lets sunshine in , its does not give such a clear view in or out, which might be a problem for you ? As well as its strength(10mm) it also has vey good thermal insulaltion in winter.

    Our greenhouse has the typical aluminium profile and with 10mm you can still fit the standard types of glazing clips, though we did add a bead of clear silicone on the internal surfaces.
    Its stayed in place for many years.
     
  6. pete

    pete Growing a bit of this and a bit of that....

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    I've had some experience of clear acrylic sheet, years ago I had one of those lean tos that had curved sections at the eves.
    In that case it was 3 mm and the fact it was bent in a curve gave it rigidity, not sure how ridgid it would be as a flat sheet in a gale.

    plastics usually expand more when heated than glass, so I'm told, so I wouldn't use glue that won't allow expansion.
    Something like glazing silicon might be better, but the original clips might work, you just might need to add a few extra.

    I have 10mm twinwall polycarbonate in one side of my greenhouse, but I fixed that with timber beads as the original clips just wouldn't work with the extra thickness, I bedded it on foam glazing tape.

    The cut to size places are obviously going the charge for cutting to size, if you can cut it yourself you can buy most of these in places like Wickes I think, haven't checked if they still sell these products.
     
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