When the gap between the panes clouds over, or a crack appears, the frame is often perfectly sound. Changing the glass alone can be cheaper and quicker than replacing the whole rooflight, and the opening, kerb and ceiling are left alone. The catch is that the glass is made to measure, so this is a two-visit job: one to measure and confirm what is in there, and one to fit once the new unit has been made.
The first visit is charged, and we tell you the price before you book it. To keep it short, send photos of the glass, the frame and any label or etching in the corner of the pane first. Some rooflights are bonded units where the glass and frame cannot be parted, and some frames are too tired to be worth reglazing. If that is the case, we will tell you, and you can compare glass-only and full replacement prices side by side.
What's included
- Measuring visit to size the glass and identify its make-up
- Sealed unit ordered to match or improve on the original glass
- Old glass taken out safely and removed from site
- Frame rebate cleaned and checked for damage, corrosion or failed seals
- New glazing tapes, gaskets or sealant fitted to suit the frame
- New unit set on packers, then beaded, capped or bonded as designed
- Joints water tested and the glass cleaned inside and out
Guide prices
Small sealed unit
Misted or cracked unit up to about 1 m² measured, made and refitted
Medium sealed unit
Units up to about 2 m², or toughened and laminated
Large or specialist
Triple glazed, solar-control or heavy units needing lifting gear
Guide ranges. The first visit is charged and priced before booking; any new glass is priced in writing before work starts. Scaffold, access towers or a crane are priced separately if the job needs them, and building control or building warrant fees, where a job needs them, are shown as their own line.
How the glass is replaced
- Photos firstSend close photos of the glass, the frame corners and any marks etched into the pane. They tell us the likely make-up and whether glass-only work is realistic.
- Priced measuring visitWe quote the measuring visit before booking it. On the day the fitter measures the glass, checks the frame and confirms the coating and safety glass needed.
- Glass made to orderThe new sealed unit is ordered to the measured size. Made-to-order glass cannot be cut down afterwards, so the sizes are checked against the frame before ordering.
- Old glass outOn the fitting visit, beads, caps or seals are released and the old unit lifted out with suction lifters, keeping fragments contained if the glass is cracked.
- New glass inThe rebate is cleaned, new tapes or gaskets fitted, and the unit set on packers so its weight sits correctly. Caps and beads go back on and the edges are sealed.
- Test and tidyJoints are water tested where it is safe to do so, the glass is cleaned on both faces and the old unit taken away with the packaging.
Things we check before quoting
Can the glass come out?
We check whether your rooflight has removable glass or a bonded unit before booking a fitting visit. Some designs hold the glass in with caps and beads, while others bond it to the frame at the factory, and those usually mean replacing the whole rooflight.
Matching the glass make-up
We identify the existing glass so the replacement performs at least as well. That means the number of panes, the coatings, any solar-control layer and whether the inner pane is toughened or laminated, which matters wherever glass sits over people.
Weight and lifting
We plan how a heavy pane gets onto the roof and into the frame. Larger and triple-glazed units can be too heavy for two people on a roof, so lifting gear may be needed, and that is priced before you book rather than added afterwards.
Condition of the frame
We look at the frame closely before committing to new glass. If the frame is cracked, twisted, badly corroded or leaking at the kerb, new glass will not fix the real problem, and a full replacement may be the better use of your money.
Condensation or a failed seal
We confirm whether the mist is inside the sealed unit or on the room-side surface. Mist between the panes means the seal has failed and the glass needs replacing, but surface condensation usually points to ventilation or a cold reveal, which new glass will not cure.
Planning and building regulations
Replacing only the sealed unit leaves the frame and opening untouched, but the new glass should still perform no worse than the glass it replaces. In Scotland the standards say the same for glazing-only work. We match or improve the safety glass already in the frame, since toughened or laminated panes are the usual choice for rooflights. If the job grows into a full replacement, that is a controlled fitting in homes in England and Wales, and we explain what it means before you decide.
| Nation | What usually applies |
|---|---|
| England | New openings usually need building regulations approval. Replacements are controlled fittings; we are not scheme-registered, so we notify them to building control and show the fee on the quote. Rooflights in existing homes must meet 2.2 W/m²K (roof windows 1.4 or WER Band B). Most house rooflights are permitted development if they project no more than 0.15 m; listed buildings need consent. |
| Wales | New openings generally need building regulations approval; replacements need a scheme installer's certificate or a building notice, and we use a building notice. Energy limits are 2.2 W/m²K for rooflights and 1.4 for roof windows. Rooflights aren't permitted development in conservation areas, National Parks, AONBs or World Heritage Sites. |
| Scotland | New rooflights need a building warrant. Replacing a rooflight complete with its frame doesn't, but must meet the standards, including 1.6 W/m²K. Householder permitted development rights don't apply in conservation areas; listed buildings need consent. |
| Northern Ireland | New openings alter the roof structure, so expect a building control application; confirm with your council. Rooflights in existing homes must meet WER Band C or 1.6 W/m²K. Permitted development (Class B) allows up to 15 cm on road-facing slopes, at least 0.5 m from ridge, eaves and verge; not in conservation areas or listed curtilage. |
A summary, not legal advice. We confirm what applies to your address before you commit. Read the full guide.
Questions about rooflight glass replacement
Why has my rooflight glass misted inside?
Misting between the panes means the edge seal of the sealed unit has failed and moist air has got into the cavity. It cannot be wiped away and rarely clears on its own. The frame may still be fine, in which case the glass alone can be replaced, but if the frame is also leaking or damaged, a full replacement is worth pricing.
Is the measuring visit charged?
Yes. Glass replacement starts with a measuring visit, which is charged, and we tell you the price before you book it. Sending photos first often lets us confirm whether glass-only work is possible, so you do not pay for a visit that ends with the advice to replace the whole rooflight.
How long does it take to get new glass?
The glass is made to order once the measurements are confirmed, so there is a wait between the two visits. We give you the expected lead time with the quote; it depends on the glass type and the supplier's workload rather than anything we can speed up. The fitting visit itself is usually about half a day.
Can you upgrade to better glass?
Often, yes. A replacement unit can be ordered with a solar-control coating to cut glare and heat, a warmer edge spacer or a laminated inner pane, as long as the frame can take the thickness and weight. We check the rebate depth on the measuring visit before suggesting anything the frame cannot hold.
Can you replace glass in a roof lantern?
Yes, lantern panes are usually held by caps or bars and can be changed one at a time. Each pane is measured individually, because lantern glass is often tapered or cut to a shape. If several panes have failed at once, it may be worth comparing the cost with replacing the lantern.
