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How to Replace Greenhouse and Shed Windows

Whoops...there goes a pane in your greenhouse, or your shed, or your garage or another kind of outbuilding. Maybe one or more of the panes are warped. That's the thing with glass. It breaks, it warps, it gets damaged, it's just not as tough as modern acrylic or polycarbonate alternatives. It can even lose its transparency over time, which means it no longer does the job it was designed for.

You don't want to give in and buy a new greenhouse or shed quite yet. These days, when life is all about recycling, replacing and re-purposing rather than throwing away, you need new panes.

Luckily it's super-easy to replace a broken or warped greenhouse or shed window with a piece of acrylic or polycarbonate. Better still, both materials are a whole lot better than glass in all sorts of ways.

Why acrylic and polycarbonate are better than glass

  • Polycarbonate has more than 30 times the impact resistance of glass, and acrylic has 10-24 times the impact resistance of glass
  • They offer excellent UV protection
  • Both are safer than glass
  • Both materials can suffer scratches, so you can't use abrasive cleaning materials on them, but it’s easier to smooth out scratches in acrylic than in polycarbonate
  • Acrylic is a little clearer than polycarbonate, slightly more transparent
  • Polycarbonate usually costs more than acrylic, sometimes a lot more
  • Acrylic is easier to cut while polycarbonate is often your best choice if you need to drill
  • Acrylic is easier to break than polycarbonate, especially if you drill close to the edge
  • Acrylic sheet can be polished to a smooth finish, but you can't polish polycarbonate
  • Acrylic is extremely rigid and cracks more easily than polycarbonate
  • Polycarbonate comes in both rigid and flexible grades
  • Both are salt-resistant so good for coastal areas
  • Both have high tensile strength and are really difficult to break
  • Both are 100% recyclable

We'll help you make the right choice if you're not sure which to choose – please get in touch (link to contact page) to discuss your project.

DIY window replacement in 10 simple steps

If you're not confident, get a professional in. But most people can do a great job of replacing a windowpane in a greenhouse or shed on a DIY basis. All you need is common sense and a little DIY experience. Here's how to do it.

  1. Measure the dimensions of the window frame to make sure you get the perfect fit, then send or bring your measurements to us and we'll cut the polycarbonate or acrylic sheet to size for you
  2. Gather together your equipment - a putty knife or old butter knife, heavy-duty work gloves, tape measure, razor blade, some glazing points, window putty or adhesive silicone sealant, plus your acrylic or polycarbonate replacement pane
  3. It makes sense to protect your eyes with goggles, just in case, and cover the floor beneath your working area with newspaper
  4. Remove the broken glass and sweep up all the broken bits – that's why you need thick work gloves. If there's old glass stuck in the frame take great care, gently hooking out the biggest shards first. and the small ones last. If it's stuck fast, you can often get a pane out by gaffer-taping over the outside of it, making sure all the shards are taped, then using a hammer to gently dislodge the pane. Goggles and gloves are a must at this stage
  5. Loosen all the old putty using a putty or butter knife, making sure you get it all off to leave a clean surface. You can shave off any awkward scraps using a razor blade or craft scalpel
  6. Remove the old glazing points and make sure you have a smooth, even and clean surface to fix the new pane too, otherwise, you'll compromise its structural integrity
  7. Evenly apply putty or adhesive silicone sealant all around the edge of the frame, creating a uniform look
  8. Gently press the new pane into the putty or sealant, using glazing points to make it sit squarely in the frame - 2 -3 glazing points on each side of the frame is good, more if the pane is a big one
  9. Apply a final layer of putty or sealant evenly along with the entire frame and give the outer edge a neat 45-degree angle, using the face of your knife blade. This helps protect the junction and frame itself from condensation and rain
  10. Remove any debris then let the putty or sealant dry fully

Window putty or silicone adhesive sealant?

You can use either putty or a white quick-drying silicone adhesive filler to stick the new pane to the window frame. They work equally well because acrylic and polycarbonate are both so much lighter than glass.

Need help choosing the right replacement pane?

If you need help choosing the right material, measuring the pane size or any other part of the project, we're always pleased to help. Call our friendly team or use our Live Chat facility.

Painted shed with acrylic shed windows

Replacement Shed Windows

Looking to replace your shed window? No need to worry about searching for the right size, we provide cut to size shed windows in three different materials, Acrylic, Polycarbonate, and HIPS. Get yours now with quick delivery and competitive prices.

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Rated 4.8/5 on Feefo

Cut to the right size, smooth edges and the screw holes in the right place. We’ll done.
Very pleased with product, just as I ordered. Would buy from them again.
Easy to order, prompt delivery and good quality wood.
Very accurate, clean cutting of high quality marine ply. Excellent packing. Pity about the high charge for small order.

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