If your roof is being re-covered and the rooflights are more than about ten years old, replace them at the same time. You are paying for scaffold and access once, the covering is already coming off around the units, and a fresh unit with a new flashing kit weathers into new tiles as a single clean assembly. Keep the old units and the roofer has to dress brand new tiles back to a tired flashing kit and a perished frame, which becomes the weak point in an otherwise new roof and often leaks within a season or two. The saving from keeping the old units is small and short-lived. The cost of going back up to sort them out later is not.
This answer is about the timing decision. The cost of the units themselves is on pitched roof rooflight installation cost, and why the flashing kit has to match the new covering is on choosing and fitting the flashing kit.
The cost logic
Two of the biggest costs in any rooflight job are access and disturbing the covering. On a re-roof, you are paying both anyway. The scaffold is up for the whole roof, and the tiles or slates around every rooflight are being lifted regardless. Adding the rooflight replacement into that work means you avoid a second scaffold, a second visit, and a second round of lifting the covering later. The marginal cost of the new units at re-roof time is much lower than the cost of the same units fitted as a standalone job with their own scaffold.
| Factor | At re-roof | As a separate job later |
|---|---|---|
| Scaffold | Already up, shared | Second scaffold, priced again |
| Covering disturbance | Already off around the units | New covering lifted and re-bedded, breakage risk |
| Flashing | New kit weathered into new tiles | New tiles dressed back to old kit, weak point |
| Weathering life | Whole assembly ages together | Old unit is the first thing to fail in a new roof |
| Overall cost | Lower, marginal add to the re-roof | Higher, full standalone job |
The weathering logic
This is the part that matters even more than the cost. When a roof is re-covered, the new tiles or slates are laid to fresh battens and dressed neatly around whatever is in the roof. If the old rooflights stay, the roofer has to dress brand new covering back to a flashing kit that is years old, possibly the wrong profile for the new tiles, and a frame whose seals and timber are past their best. That junction becomes the one tired detail in an otherwise new roof, and water finds the tired detail first. It is common to see a re-roofed house spring a leak at an old rooflight within a season, precisely because everything around it was renewed and it was not.
Worse, if the new covering is a different profile from the old, an old flat kit may no longer suit the new tiles at all. A re-roof that swaps, say, old plain tiles for a deeper interlocking tile leaves the old rooflight flashing bridging the new profile, which leaks under every course. The flashing has to match the covering, and a new covering usually means a new kit. That logic is on what flashing you need for a slate roof and applies to every covering.
When it is worth keeping the existing units
It is not always automatic. Keeping the existing rooflights can make sense if:
- The units are genuinely recent, within a few years, with sound seals, good glazing and a flashing kit that suits the new covering.
- The new covering is the same profile as the old, so the existing flashing still matches.
- The units are already a modern, well-performing specification you have no reason to upgrade.
Even then, we would lift and re-dress the flashing into the new covering as part of the re-roof, because the junction is being disturbed anyway. If the units are old, draughty, misting up or a different profile from the new tiles, replacement is the clear call. The draught and seal side of that judgement is on draughty, cold loft rooflights.
We do not patch the old ones back in
One thing we will not do is reseal or patch an old rooflight to nurse it through a re-roof. That is the false economy the whole timing argument warns against. If the units are staying, they stay because they are sound, and their flashing is renewed into the new covering. If they are not sound, they are replaced. We do not offer resealing or repair as a service, and we never advise anyone onto the roof to have a look, because the survey settles it from a scaffold and inside the loft. The replace-not-patch logic across worn components is on rotten rooflights, replace not repair.
Coordinate the trades early. If you have a roofer lined up for a re-cover, tell us before the scaffold goes up so we can survey and have the units and the correct flashing kit on site to fit into the new covering as it is laid. Fitting rooflights into a re-roof works best when both trades are planned together, not when the rooflights are an afterthought once the tiles are already back on.
Related questions
How long the rooflight side adds to a re-roof is small, covered on how long it takes to fit a pitched rooflight. If you are upgrading the whole roof’s performance, the glazing U-value side is on the energy efficient skylight installation page, and doing the rooflights at re-roof time is the natural moment to lift their thermal specification too.
Common questions about re-roofing and rooflights
Should I replace my rooflights when the roof is re-covered?
Almost always, if they are more than about ten years old. The scaffold is up and the covering is off around them anyway, so the marginal cost is low, and a new unit weathers into new tiles as a clean assembly. Keep an old unit and the roofer dresses new tiles back to a tired flashing kit and perished frame, which becomes the weak point in a new roof and often leaks within a season.
Can I keep my existing rooflights during a re-roof?
Only if they are genuinely recent, sound, and the new covering is the same profile so the existing flashing still suits it. Even then the flashing is lifted and re-dressed into the new covering. If the units are old, draughty, misting, or the new tiles are a different profile from the old, replacement is the clear call, because an old flat kit will not weather a new deeper covering.
Will fitting rooflights into a re-roof slow the roofer down?
Very little, if it is planned. Tell us before the scaffold goes up so we have the units and the correct flashing kit on site to fit as the covering is laid. Coordinating both trades from the start is far smoother than treating the rooflights as an afterthought once the tiles are back on, which means disturbing new covering to fit them.
Plan your rooflights into the re-roof
Tell us your roof is due for re-covering and roughly what covering is going on, and we will survey before the scaffold goes up, specify units and flashing to match the new covering, and give you one written fixed price to fit them into the new roof. Every installation carries a 10-year workmanship guarantee and the installers have 25 years fitting rooflights behind them.
Request a fixed quote for rooflights in a re-roof across Ipswich, Suffolk or north Essex, or read our published prices first.
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.