If your roof window glass is broken, make it safe from inside the room. Clear the floor directly below, keep people and pets out, and tape a sheet of polythene or a rigid board over the inside of the opening to hold loose fragments and keep the weather out. Do not climb onto the roof. Do not pick at the glass from above.
Roof glazing is designed not to shower a room with shards, so a broken pane is usually less dangerous inside than it looks. The risk is falling debris and an open hole to the weather, and both are managed from below. Here is how to secure it, how the two glass types behave, and how quickly a replacement goes in.
Make it safe from inside, step by step
- Clear the area below. Move everything out from under the window, furniture, bedding, electricals, and keep the space clear until it is dealt with. Anything that falls, falls straight down.
- Keep people and pets out. Close the room off. Bare feet and broken glass do not mix, and a pet under a stressed pane is a hazard to itself and to you.
- Do not pull at the glass. Leave loose or hanging fragments where they are. Prising them out from inside can drop a piece or crack the pane further. If small pieces are already on the floor, sweep with a stiff brush and dustpan, not your hands.
- Cover the opening from inside. Tape heavy polythene, or fix a thin rigid board, across the inside face of the window. This holds fragments in place and keeps rain out of the room as a temporary measure.
- Catch any water. Put a bucket and towels below in case the seal is compromised and rain tracks in.
- Stay off the roof. Do not go outside to tape or board the glass from above. A broken roof window at height, in weather, with loose glass, is exactly the situation that turns a glazing bill into an injury. Everything needed is done from inside; if it cannot be, call us.
The one rule. Nobody goes on the roof. Broken glass is a replacement job, not an emergency worth a fall. Secure the room from below, cover the opening from inside, and get it looked at.
Laminated or toughened: why the break looks different
How your broken pane behaves depends on which type of glass it is, and modern roof windows use both, usually laminated on the inner pane for exactly this reason.
Laminated glass has a plastic interlayer bonded between two sheets. When it breaks it holds together, cracked but in one piece, stuck to the membrane like a car windscreen. It sags and spiders rather than falling out, which is why it is specified as the inner pane over habitable rooms: a break stays overhead instead of landing on the bed below. If your inner pane is cracked but intact and hanging together, that is laminated glass doing its job.
Toughened glass is heat-treated so that when it fails it crumbles into thousands of small, blunt granules rather than long sharp shards. It is far safer than ordinary glass, but it does let go all at once and drop its granules. If your window has scattered a pile of small squarish pieces, that was toughened glass. The granules are blunt, but there are a lot of them and they get everywhere, so the clear-the-floor step still matters.
Either way, a break in one pane of a sealed unit means the whole double-glazed unit has to come out. You cannot replace a single sheet of a bonded, gas-filled unit; the two panes, the spacer and the seal are one component.
How quickly a replacement goes in
Once we know the size, a replacement is fast. The size comes off the data plate on the top edge of the sash, or we measure the structural opening at survey. With that confirmed, a standard-size unit is typically a two to three week order, and the fit itself is a matter of hours: strip the working area, take the old unit out, set the new frame, fit the collars and the flashing kit matched to your covering, re-hang the covering. The roof is watertight the same day and never left open overnight.
If the weather is severe and the opening cannot be safely secured from inside while you wait for the unit, we can attend to sheet and secure it properly first, then fit the replacement when it arrives. What we do not do is send someone up to patch a pane, because on a roof window there is nothing to patch to.
Why a broken unit on an old window means a new window
If the broken pane is in a modern window in good condition, a like-for-like replacement unit is the answer. But on an older window, a blown or broken unit is rarely the only problem, and this is where honesty saves you money twice over.
A window old enough to have a failed pane has usually been through fifteen or more Suffolk winters. The sealed unit for that generation is frequently obsolete, because the glass thickness and glazing bead changed when the frame profile changed. And even where a unit can be sourced, the frame timber and the flashing beneath it are on the same clock, so fitting new glass into a tired frame spends money on the one part that broke while the rest carries on failing. On a window that age the sound answer is a whole new window, with new flashing and new collars, backed by our 10-year workmanship guarantee. The full reasoning is on our replace not repair page, and the tipping point is set out on when to replace a roof window.
While you are checking the window, note anything else. A pane that is also misted between the layers points to a blown sealed unit, covered on roof window misting. A sash that will not close alongside broken glass is covered on roof window will not close, and it changes how urgently the opening needs securing. The whole survey-to-watertight process is on our VELUX window installation page.
Get a fixed price for a replacement
Secure the room from inside first and stay off the roof. Then photograph the window from inside, and the data plate if you can safely reach it, and send them over. We will confirm the size, tell you whether a like-for-like unit or a whole-window replacement is the right call, and give you one fixed written price. Request a fixed quote and we will get the opening watertight and the new glass in.
Thinking about this job? We survey across Ipswich, Suffolk and north Essex and give you a fixed price before any work starts, with a 10-year workmanship guarantee.