Replace a shed window with acrylic — HomeGraft

Swap a cracked or broken shed window for tough acrylic, measuring, cutting and resealing it so rain stays out.

SW-01Gather your tools and materialsLay a dust sheet or old towel under the window to catch glass splinters and off-cuts. Check you have your acrylic sheet, jigsaw, tape measure, sealant and beading pins to hand before you start. Working in one go is much easier than stopping halfway through.

1 each · Dust sheet or old towel

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SW-02Put safety gear on and check the shedBroken or cracked glass can shed sharp slivers you won't see, so wear gloves and safety glasses before you touch the frame. If your shed has mains power run to it, don't drill or force anything near known cable routes, and switch off at the consumer unit first if you're at all unsure. Check behind any cladding near the frame for wasps, spiders or nesting birds before you start prising things apart.

1 pair · Work gloves

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1 each · Safety glasses

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SW-03Remove the old glazing beadingGently prise the wooden beading away from the frame with a flat scraper, working along each side rather than levering hard in one spot. Keep the pins or tacks in a pot so you can see how many you'll need to replace. If the beading is sound, set it aside to reuse.

1 each · Flat scraper or chisel

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SW-04Take out the old glass and dispose of it safelySupport the pane from underneath as you lift it clear, since old glass can be brittle and unpredictable. Wrap broken pieces in newspaper or cardboard and tape the parcel shut before binning it, and mark it as glass so nobody is caught out. Sweep up any small shards from the sill and surrounding ground straight away.

1 sheet · Newspaper or cardboard

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1 each · Dustpan and brush

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SW-05Measure the window openingMeasure the width and height of the aperture at both edges and the middle, since old shed frames are rarely perfectly square. Use the smallest measurement and take off 2-3mm all round so the acrylic isn't a tight fit. Acrylic expands slightly in heat, so this small gap matters more than it would with glass.

1 each · Tape measure

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1 each · Pencil

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SW-06Mark and cut the acrylic sheetLeave the protective film on the acrylic and mark your cut lines on it with a pencil and straight edge. Cut with a jigsaw fitted with a fine-tooth or plastic-cutting blade, running it slowly and supporting the sheet close to the cut to stop it vibrating and cracking. Run masking tape along the cut line first if you're worried about chipping the edge.

1 each · Acrylic sheet (3-4mm, cut to size)

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1 each · Fine-tooth or plastic-cutting jigsaw blade

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1 roll · Masking tape

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SW-07Smooth the cut edgesRun fine sandpaper or a file lightly along each cut edge to remove any sharpness or rough patches. Peel the protective film off both sides only once you're ready to fit the sheet, to keep it scratch-free until the last minute.

1 sheet · Fine sandpaper (120-180 grit)

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SW-08Dry-fit the acrylicPlace the sheet into the frame without fixing it yet, and check the gap is even all the way round. If it's too tight anywhere, take it back out and trim that edge slightly rather than forcing it in.

SW-09Fix the beading back and seal the edgesPin the glazing beading back over the acrylic using the original holes where you can, tapping pins in gently so you don't crack the sheet. Don't pin it down so tight that it can't move slightly as it warms up. Run a bead of exterior-grade silicone sealant along the outside join between frame and acrylic to keep rain out.

20 each · Glazing pins

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1 tube · Exterior silicone sealant

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1 each · Sealant gun

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SW-10Clean up and check your workWipe the acrylic with a soft cloth and mild soapy water, never a dry cloth or window cleaner, since these can scratch the surface. Sweep up any remaining off-cuts and swarf, and check the sealant line is smooth and unbroken all the way round. Leave the sealant to cure for the time stated on the tube before shutting the shed up in wet weather.

1 each · Soft cloth

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1 each · Mild soap

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