How Much Does It Cost to Replace an Existing Roof Lantern?
Replacing an existing roof lantern in Suffolk typically costs a little more than fitting the same size new, once removal, disposal and making good are counted, and it can cost considerably more if the old kerb has failed. A straight like-for-like swap onto a sound kerb might land close to the new-install figure of £4,600 to £8,400 for mid-to-large sizes. A replacement that also needs the kerb rebuilt and the modern lantern sized to a non-standard old opening adds a meaningful amount on top. The variable is almost never the new lantern. It is what the old one was hiding.
This matters because a replacement is a different job from a first install, and pricing it like one is how quotes go wrong. This sits under our main roof lantern installation page, and the general cost method is on our roof lantern cost page.
Why replacement is not just a fresh install
A first install goes into a new or newly formed opening built to suit the lantern. A replacement goes onto a structure built twenty years ago for a different unit, and four costs appear that a new install does not carry.
- Removal and disposal. The old lantern has to come off in one piece or be dismantled safely, and the old glazing, gaskets and any perished timber removed from site. Old sealed units are heavy and awkward, and disposal is a real line rather than a rounding error.
- Kerb remediation. This is the big one. The kerb the old lantern sat on cannot be judged until the unit is off and it is exposed. A sound kerb needing only a fresh covering adds little. A rotten, undersized or uninsulated kerb, which is common under a failed lantern, needs full rebuilding, and that is the single largest variable on a replacement.
- Size and profile mismatch. A lantern from the mid-2000s was made to that era’s sizes and frame profiles. A modern replacement rarely matches the old external kerb dimension exactly, so the opening or the kerb often needs adjusting to take a current unit. Slim modern profiles also sit differently from bulky older ones.
- Internal making good. Taking the old unit out disturbs the plaster reveal, and a different frame profile changes how the new unit meets the ceiling. The reveal usually needs re-forming, boarding and skimming to a clean finish.
| Line item | First install | Replacement |
|---|---|---|
| New lantern unit | Yes | Yes, similar cost |
| Removal and disposal of old unit | None | £200 to £500 |
| Kerb | Built once, in the fitting figure | Nothing if sound; a full rebuild if not |
| Opening adjustment for profile mismatch | Not applicable | Sometimes needed |
| Internal making good | New reveal, planned | Re-forming a disturbed reveal |
The kerb is where the money hides
If a lantern has been misting, draughty or tracking water, the kerb underneath has usually been damp for years, and the timber in it is often the real failure by the time anything shows inside. That cannot be priced from a photograph or a phone call, which is why an honest replacement quote gives the kerb as a range until the old unit is off and it has been inspected. Where the kerb is sound we rebuild the covering detail and set the new lantern on it cheaply. Where it is not, rebuilding it is the only intervention that actually ends the problem, and it is the reason two replacement quotes can differ by more than a thousand pounds. Our page on what a roof lantern upstand is explains why this detail carries the whole installation.
We do not reseal or patch a failed lantern. A reseal buys twelve to eighteen months and touches none of the failed sealed units, perished gaskets or wet kerb timber underneath. It is a payment plan for the replacement you will buy anyway. We replace, and we rebuild the kerb where it needs it, which is the fix that lasts. Our page on reseal or replace sets out that arithmetic.
The upside of replacing
A replacement is not only a cost. A lantern from 2005 has a whole-unit U-value around 2.8 to 3.2 W/m²K, against roughly 1.2 to 1.4 for what we fit today, so the room stops being cold along the ridge and the heating stops leaking through the roof. Modern solar control glazing cuts summer overheating that older clear glass never addressed, and a current unit comes with a 10-year workmanship guarantee behind the whole installation, kerb included. You are not buying the same thing again; you are buying a materially better roof.
Related questions
- How much does a 3m x 2m roof lantern cost fitted? for a worked price on a common size.
- Is an aluminium roof lantern cheaper than timber? when choosing the replacement frame.
- Roof lantern leaking in heavy rain: what to do now? if the old one is failing as you read this.
For how the old lantern’s symptoms are read, see leaking roof lantern diagnosis, and for the general pricing method, what a roof lantern costs.
Get the replacement priced properly
Send us the old lantern’s size, its age if you know it, and what it is doing now. We will survey it, and where the kerb condition is the unknown we will say so and price it as a range until we can see it, then confirm one fixed figure. Request a fixed quote for roof lantern replacement in Ipswich, Suffolk or north Essex, or compare published prices across every service 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.