How to Board Up a Broken Window Safely

When a window is broken, boarding it up properly is what actually keeps a property secure, dry and safe until the glass can be replaced. Done badly, a board-up can look secure while actually letting in weather, failing to keep the opening rigid, or damaging the frame in the process. Here's what a proper job involves, and where the common mistakes creep in.

Why a quick fix isn't the same as a safe fix

It's tempting, especially late at night or in a panic after a break-in, to grab whatever's to hand — a bin bag and tape, a piece of cardboard, a spare bit of wood propped against the frame. These might keep the worst of the rain off for an hour, but they won't hold in wind, won't deter anyone trying to get back in, and can actually make the eventual repair harder if glass shards get left in the frame underneath.

A proper board-up is fixed securely into the frame or masonry reveal, cut to the exact size of the opening, and made from a board thick enough to resist being pushed through. It should feel as solid as the window it's replacing, not just a temporary cover.

Clearing the glass first

Before any board goes up, the broken glass needs to be cleared from the frame and the surrounding area. Loose or hanging shards left in situ are a genuine injury risk — both to anyone in the property and to whoever fits the permanent glass later. This is closely tied to general broken glass safety and clean-up, and it's worth reading that guide alongside this one if there's glass debris inside the room as well as at the window.

Gloves and eye protection matter here, even for what looks like a small crack. Toughened glass in particular can fracture into a huge number of small pieces that scatter well beyond the immediate area, and laminated glass can leave large, heavy shards attached to the interlayer that need careful handling.

Choosing the right material

Plywood is the standard choice for boarding up domestic and commercial glazing — it's rigid, holds screws well, and is available in a thickness that resists reasonable force. As a rough guide, 12mm to 18mm exterior-grade plywood is suitable for most residential openings, with thicker board (18mm+) or reinforced boarding used for shopfronts and higher-risk commercial premises.

Fixing it correctly

The board needs to be fixed into something structural — the window or door frame itself, or the surrounding masonry — rather than just into the thin glazing bead that held the glass in place. Fixing only into the bead means the board can be levered off with very little force, defeating the point of boarding up in the first place.

On uPVC and aluminium frames this needs a bit of care, since over-tightening screws or drilling in the wrong place can crack the frame or damage the reinforcement inside. This is one of the reasons a professional board-up, even as a temporary measure, tends to hold up better than a DIY attempt — it's fixed properly the first time.

Shopfronts and larger openings

Commercial glazing brings its own challenges — shopfront panes are often much larger, sit in aluminium or steel frames, and need to look reasonably presentable to customers as well as being secure. For a smashed shop window specifically, our guide on what to do when a shop window is smashed goes into more detail on securing a commercial frontage and dealing with insurers and landlords.

When to call a professional

A single small domestic pane can sometimes be safely boarded by a competent DIYer with the right materials. But for anything at height, any door (where the frame and lock mechanism need to stay usable), or any shopfront, it's worth calling a glazier rather than improvising. Getting it wrong can mean the board fails overnight, or that fixing screws damage the frame in a way that complicates the permanent repair.

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Frequently asked questions

What thickness of plywood should I use to board up a window?

For most domestic windows, 12mm to 18mm exterior-grade plywood is sufficient. Larger openings, doors, and shopfronts generally need thicker or reinforced boarding for real security.

Can I board up a window myself?

For a small, ground-floor domestic pane with the right tools and materials, yes. For anything larger, at height, involving a door lock, or a commercial unit, it's safer and more effective to call a glazier who can fix it properly first time.

How long can a board-up safely stay in place?

A well-fitted board can hold for several days to a couple of weeks if needed, though it's always best treated as temporary — the permanent glass should be arranged as soon as practical, particularly ahead of poor weather.

Will boarding up affect my insurance claim?

No — insurers generally expect a broken window to be made safe promptly, and a proper board-up is evidence you've taken reasonable steps to prevent further damage. Keep photos and any receipts, as covered in our guide to insurance claims for broken glass.

Is it dangerous to clear broken glass myself before boarding?

It can be, particularly with toughened glass that shatters into many small pieces. Gloves, sturdy footwear and care around any large shards are essential — see our full guide on broken glass safety and clean-up.

Call Mark on 07535 916982 or request a callback.