How to board up a window, safely, and when not to DIY

Most "how to board up a window" guides are written by people who've never done it at 2am in the rain. This one is written by London glaziers who do it most weeks, including an honest list of the jobs you really shouldn't attempt yourself.

Broken glass safety comes before the board

Before any boarding up, deal with the glass: it injures more people during the clean-up than during the original break. Annealed (standard) window glass breaks into long blade-like shards that keep dropping from the frame for hours afterwards as the putty or gasket relaxes.

• Gloves, safety glasses, solid shoes. Gardening gloves aren't enough for shard removal, so use rigger or cut-resistant gloves.
• Clear the room of children and pets, and lay a dust sheet or flattened cardboard under the window before you start.
• Remove loose shards top-down, wiggling each free rather than pulling. Anything firmly held in the frame can stay: the board will cover it.
• Never bag glass loose. Use a rigid bucket or box, then double-wrap and label it "broken glass" for the bin crew.
• Toughened glass (kitchen doors, low-level glazing) crumbles into cubes, safer, but thousands of pieces. Vacuum only after sweeping; cubes hide in carpet pile for weeks.

Boarding up a window in 6 steps

1. Make the area safe

   Gear on, area cleared, dust sheet down, loose shards removed top-down into a rigid container, as above. Ten careful minutes here saves a trip to A&E.

2. Photograph everything for insurance

   Wide shots and close-ups, inside and out, before you move or fix anything. Include whatever caused the damage, the football, the brick, the storm-fallen branch. Insurers expect evidence of the damage before temporary repairs.

3. Measure the opening: frame, not glass

   Measure the full visible frame width and height in millimetres. Add a 50-75mm overlap on every side so your screws land in solid frame material rather than the glazing rebate.

4. Cut 18mm OSB to size

   18mm OSB3 is the professional standard: rigid enough that it can't be flexed and popped out, cheap (£15-£25 covers most windows), and weather-tolerant for a short stint. 12mm exterior ply is the absolute minimum for small ground-floor panes. Any merchant will cut it for you.

5. Screw to the frame, not the brick, where possible

   Drive 50mm screws through the board into the window frame every 200-300mm around the perimeter. Fixing to the frame holds better than masonry plugs in old London brick, leaves no wall damage, and comes off cleanly when the glazier fits the new glass. Only go into masonry if the frame itself is wrecked, which is a sign this isn't a DIY job anyway.

6. Seal, test, and book the reglaze

   Tape or foam any rain gaps, then try to lever the board by hand: if you can move it, a burglar can too, so add screws. Finally, book the actual glass replacement: a board is a days-not-weeks fix.

A board that flexes is a board that comes off. If you can move it by hand, add more screws, or call someone who does this nightly.

Insurance evidence: the photos that get claims paid

Take photos before, during and after the temporary repair, and keep every receipt. From handling insurance work for London landlords and homeowners, the claims that sail through all have the same evidence pack:

• Wide shot of the whole window from inside and outside, timestamped.
• Close-ups of the point of impact or forced entry marks.
• The cause, where visible, brick, branch, damaged lock.
• A crime reference number from the police (101 or online) for any break-in or vandalism.
• Receipts for boards, screws and any professional make-safe callout: these are usually reimbursable as "emergency mitigation".
• A photo of the finished board, proving you mitigated further loss (a policy condition in most UK policies).

When NOT to board up a window yourself

Some board-ups genuinely aren't DIY jobs, not because the technique changes, but because the risk does. Be honest with yourself about these:

• Anything above ground floor. Working on ladders while handling a heavy board next to broken glass is how serious injuries happen. Professionals use towers, harnesses or work from inside with the right lifting technique.
• Shopfronts and commercial panes. Shopfront glass is large, heavy and often toughened or laminated; the openings need framed hoardings, not a single sheet. Insurers and landlords also expect a documented professional make-safe, see our shopfront glazing service.
• Structural or frame damage. If the frame, transom or surrounding brickwork moved, boarding can load a weakened structure. That needs assessment first.
• Glass still dropping, or overhead glazing. Rooflights, door fanlights and cracked-but-standing panes are unpredictable. Leave them to someone with the tools to take them out safely.
• After a break-in, when you feel unsafe. There's no shame in wanting the property secured by professionals at 3am rather than standing at the broken window yourself.

What does emergency board up cost in London?

Professional boarding up in London typically costs from around £100-£250 per standard window, depending on size, access, and whether it's 2pm or 2am. Shopfronts run higher because of the sheet sizes and labour involved. Two things worth knowing before you ring anyone:

• Get a fixed price before they travel. We quote from a WhatsApp photo and the price we agree is the price you pay, no call-out fee, no "supplements" invented on the doorstep. Beware of anyone who won't give a number.
• Ask whether board-up is credited against reglazing. When the same company boards up and then replaces the glass, the make-safe cost is often partly or wholly absorbed, which usually makes one call cheaper than DIY plus a separate glazier.

If the glass can be replaced on the first visit, better still, we carry common glass sizes and can often reglaze on the spot, skipping the board altogether. For everything else, our boarding up service in London runs 24/7 with a typical response under an hour, and you can get a free quote for the follow-up glazing at the same time.

Boarding up FAQs

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