Skylight Replacement: Complete Guide in Cheltenham

When an old skylight is leaking, misting up, draughty or simply tired, there comes a point where patching it up no longer makes sense. A full replacement — taking out the old unit and fitting a modern, properly weatherproofed rooflight — restores the watertightness, the daylight and the energy efficiency you had when it was new, and often improves on it. Replacement is our specialism: we carry out full skylight replacements, not piecemeal repairs, so you end up with a unit that is right rather than one that is merely limping on. This guide explains when replacement is the answer, what the work involves and what it costs across Cheltenham and Gloucestershire.

Many of the rooflights we replace were fitted decades ago, or installed poorly by a general builder without the right flashing and detailing. Replacing them properly is one of the most satisfying jobs we do — and it is a genuine point of difference for us.

Why full replacement rather than repair

Plenty of firms will attempt a repair: a bead of sealant here, a new seal there. The trouble is that sealant is a temporary fix on a unit that is failing for structural or age-related reasons. A misted double-glazed pane cannot be un-misted. A frame that has warped or perished will keep letting water in. A flashing kit that was wrong from the start will keep failing at the same point. Replacing the whole unit deals with the cause, not the symptom — and gives you a fresh written guarantee on our workmanship rather than a fix that may fail again next winter.

Signs your skylight needs replacing

Look out for these common warning signs, all of which we see regularly on older Cheltenham and Cotswold roofs:

• Leaks or water staining: damp patches, drips or tide-marks on the ceiling around the rooflight, especially after heavy Gloucestershire rain.
• Misting between the panes: condensation trapped inside a double-glazed unit means the seal has failed and the glazing can only be replaced, not cleared.
• Draughts and cold spots: a noticeable chill or air movement near the skylight, pointing to perished seals or a failing frame.
• Discoloured or brittle plastic: old polycarbonate or acrylic domes that have yellowed, dulled or cracked with age and UV exposure.
• Stiff, broken or jammed opening: a mechanism that no longer opens, closes or seals properly.
• Rotten or corroded frames: timber that has perished or metalwork that has corroded beyond reliable sealing.

If you recognise two or more of these, replacement is usually the sensible, lasting answer.

What a skylight replacement involves

A typical replacement follows a clear sequence. We begin with a free survey to measure the existing opening, assess the roof structure and covering, and confirm the right new unit. On installation day we carefully remove the old skylight and inspect the surrounding timber and weatherproofing — on older roofs there is sometimes hidden damage to put right. We then fit the new rooflight, form or renew the kerb or flashing as needed, and weatherproof it correctly to your specific roof covering, whether that is tile, slate, felt, EPDM, GRP or single-ply. Finally we make good internally so the finish is tidy.

Where the new unit is a different size to the old one, we manage the builders’ work to adapt the opening. Most domestic replacements are completed in a day, leaving you with a watertight, efficient, like-new rooflight.

Like-for-like or an upgrade?

Replacement is also a chance to improve. While the roof is open, you can move from a tired dome to sleek flat glass, from single to high-performance double or triple glazing, or from a manual unit to solar-powered opening with a rain sensor. Many homeowners take the opportunity to add solar-control glass to a sun-baked, south-facing room — see our energy-efficient skylight installation page. If you simply want the same again, a clean like-for-like swap is straightforward too.

Replacement by roof type

On a pitched roof — a loft or sloping ceiling — we replace old roof windows with modern units set neatly into the slope, with a flashing kit matched to your tiles or slate; see our pitched roof skylight installation page. On a flat roof — an extension or single-storey section — we replace domes and old rooflights with flat glass or new units on a properly formed kerb; see our flat roof skylight installation page. We also replace ageing roof lanterns with crisp, modern, slim-framed ones; see our roof lantern installation page.

Indicative costs in 2026

As a broad 2026 guide for the Cheltenham area, a straightforward like-for-like roof window replacement typically runs from around £700 to £1,400 supplied and fitted, depending on size and glazing. Replacing a flat-roof dome with a modern flat glass rooflight tends to fall in the region of £1,200 to £2,500, and replacing a roof lantern more again, according to size and specification. Where we find hidden timber damage or need to alter the opening size, that is priced transparently after survey.

These figures are indicative only. The accurate price always comes from a fixed written quote after a free survey, with no obligation.

A local note

Cheltenham’s housing stock spans grand Regency and Victorian homes, mid-century properties and modern estates, and the surrounding Cotswold villages add centuries-old stone cottages to the mix. Many of these have rooflights fitted years ago, sometimes by general builders without specialist weatherproofing, and they are now reaching the end of their life. We replace them across Cheltenham, Charlton Kings, Prestbury, Bishop’s Cleeve and out into the wider Gloucestershire countryside, taking care to detail each one correctly for its particular roof and setting.

Next steps

If your skylight is leaking, misted, draughty or simply past its best, a full replacement is the lasting fix — and it is exactly what we specialise in. We will assess the existing unit and roof, recommend the right replacement and, if you wish, the upgrades worth making while the roof is open. See the full range on our services overview, and when you are ready, get a quote for a fixed written price after a free survey, backed by our written guarantee on our workmanship.