Roof window and skylight installation across Derby — Velux and equivalent units, dormer windows and roof lights — fitted watertight with the flashing kit matched to your exact tile or slate profile.
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A roof window transforms a dark loft, landing or extension — and fitted properly it is completely watertight for decades. We install Velux and equivalent roof windows across Derby, from single units bringing light into a loft conversion to runs of windows in a new extension roof. A standard unit supplied and fitted costs £1,200–£3,000 depending on size, specification and access, with conservation-range units at the higher end.
The critical detail on any roof window is the flashing kit — the weatherproofing collar that seals the window into the surrounding roof. It must match your specific roof covering: there are different flashing kits for interlocking tiles, plain tiles, slate and low-pitch roofs, and fitting the wrong one is the single most common cause of a leaking roof window. We match the flashing to your exact Derby roof profile as standard, which is why our installs stay watertight where botched ones leak.
Beyond standard roof windows, we handle dormer windows — the projecting structures that add both light and headroom to a loft conversion — and flat roof lights for extensions and single-storey roofs. Dormer work is more involved, combining roofing, leadwork and sometimes structural elements, and is priced per project after a survey. Flat roof lanterns and lights bring dramatic light into Derby kitchen extensions and are fitted as part of the flat roof system.
A common Derby job is replacing an old, failed or draughty roof window rather than fitting a new one. Older units seize, the seals perish, and the original flashing corrodes and leaks. Replacing the unit and renewing the flashing at £900–£1,500 restores a watertight, well-insulated window and is far cheaper than dealing with the water damage a failing one causes. If your existing roof window is leaking or won't close properly, replacement is usually the sensible answer.
Good news for most Derby homeowners: roof windows that sit in the plane of the existing roof slope, not projecting beyond it, are generally permitted development and need no planning permission. This covers the great majority of Velux installations. The exceptions are properties in conservation areas — Friar Gate, the Cathedral Quarter, Little Chester — where roof windows on a visible elevation may need consent, and listed buildings, where they almost certainly do.
Dormer windows are a different matter, as they project beyond the roof and alter its shape — these often need planning permission, particularly at the front of a property or in a conservation area. Building regulations apply to the structural opening for any roof window, ensuring the rafters are correctly trimmed and supported. We advise on the planning and building control position for your specific Derby property before starting, so there are no surprises, and handle the building control side of the work.
Roof windows suit different Derby properties in different ways. The loft conversions that have added bedrooms across Derby's family suburbs — Allestree, Littleover, Mickleover, Oakwood — rely on roof windows for light and, where regulations require it, for means of escape. On these interlocking concrete-tile roofs, the standard tile flashing kit fits cleanly and installation is straightforward.
The Victorian and Edwardian slate terraces of Normanton, Peartree and Friar Gate need the slate flashing kit and a more careful approach, working with brittle century-old slate around the opening. In the Friar Gate and Cathedral Quarter conservation areas, a conservation-range roof window — with a lower profile and a central glazing bar that echoes traditional rooflights — is often the appropriate or required choice, and we fit these to suit both the property and the planning rules.
Kitchen and rear extensions across Derby increasingly feature flat roof lanterns and lights, flooding single-storey spaces with daylight. These are fitted as part of a GRP or EPDM flat roof system, where the same principle applies as on a pitched roof window: the weatherproofing detail where glass meets roof is everything, and getting it right is what keeps a beautiful roof lantern from becoming a persistent leak.
Supplied-and-fitted prices with the flashing kit matched to your roof covering. Dormers priced per project after survey. Multiple units share the access cost.
Roof windows that do not project beyond the plane of the existing roof slope are generally permitted development under the Town and Country Planning (General Permitted Development) Order 2015.Source: Town and Country Planning (GPDO) 2015, Sch.2 Pt.1 Class C
Flashing matched to your exact tile or slate profile as standard — the detail that keeps a roof window watertight for decades.
☎ Call 0133 240 5131Two Velux in our Littleover loft conversion. Flashing matched perfectly to our tiles, no leaks, and they sorted the building control side.
Conservation roof window on our Friar Gate terrace — they knew exactly which unit suited the conservation area. Watertight and looks right.
Replaced our old leaking roof window in Oakwood. New unit and flashing for far less than the water damage was going to cost. Proper job.
A leaking or ageing rooflight is a common Derby problem, and so is wanting to add light to a loft conversion or extension. Correct flashing to the surrounding covering is what makes a rooflight watertight.
When it is not the answer: If the rooflight unit is sound and only the flashing has failed, re-flashing it is enough — a full replacement would be unnecessary Read the full guide.
We check the rooflight or the proposed position, and the surrounding covering.
A fixed price for supply and fit or replacement, with the correct flashing kit for your tile or slate.
Booked as a short, contained job.
The unit is fitted or replaced and — critically — flashed correctly into the surrounding covering with the matched flashing kit.
We confirm it is watertight and the internal reveal is left ready for finishing.
| Job | Typical duration |
|---|---|
| Replace like-for-like Velux | half a day–1 day |
| Install new rooflight (existing opening) | 1 day |
| Install new rooflight (new opening) | 1–2 days |
| Re-flash existing rooflight | 2–4 hours |
| Multiple rooflights | 2–3 days |
Opening a roof for a new rooflight is scheduled for dry weather and never left open overnight.
Rooflight work needs safe roof access — a tower or scaffold depending on height and the size of the opening. Scaffold is specified for: new openings and first-floor rooflights needing sustained safe access - always itemised in your written quote, never a hidden extra, and we arrange it.
Derby's mix of Victorian terraces, post-war estates and city-centre stock means access varies street by street, from tight terraced frontages to open estate roads. Pavement scaffold and skip permits go through Derby City Council; allow a few working days on streets like Sadler Gate, the Wardwick, Friar Gate where space is tight.
| Job | Typical range | Notes |
|---|---|---|
| Replace like-for-like Velux | £450–£900 | Incl. flashing kit |
| Install in existing opening | £600–£1,200 | Supply and fit |
| Install with new opening | £1,200–£2,500 | Structural work |
| Re-flash existing rooflight | £200–£450 | Stop a leak |
| Multiple rooflights | Per scope | Discounted |
Worked example: Replacing a leaking Velux like-for-like on a loft conversion in Mickleover — about £680 including the matched flashing kit.
Staged payment on new-opening installs, balance on completion. No large deposit. VAT included.
Covering DE1, DE21, DE22, DE23, DE24 and surrounding postcodes.
Installation carries a 10-year workmanship guarantee; Velux and other quality rooflights carry their own 10–20 year manufacturer warranties on the unit.
If a fault appears in covered work, we come back and put it right. No quibbling, no re-charge.
Some internal dust when forming a new opening (sheeted off), and a day or so of work — replacements are quick and contained. You do not need to stay home for external work - we just need power and access agreed in advance.
We fit rooflights in dry conditions and never leave a roof open to the weather; the correct flashing kit is what keeps Derby's driving rain out long-term. Derby's inland Midlands position brings genuine winter frosts and Derwent-valley humidity that slows drying.
A standard roof window supplied and fitted costs £1,200–£2,000, larger or specified units £2,000–£3,000, and conservation-range units £1,500–£3,000. Flashing is matched to your roof covering as standard.
Usually not — roof windows that sit in the plane of the roof slope are generally permitted development. Exceptions are conservation areas like Friar Gate and listed buildings, where consent may be needed. We advise on your property.
Almost always the wrong flashing kit. There are different kits for tiles, slate and low-pitch roofs, and fitting the wrong one causes leaks. We match the flashing to your exact roof profile, which is why our installs stay watertight.
Yes — replacing a failed unit and renewing the flashing costs £900–£1,500 and restores a watertight, insulated window. It's far cheaper than the water damage a failing one causes. Flashing-only replacement is £300–£600.
Yes — dormers add light and headroom to loft conversions, combining roofing, leadwork and structural work. They often need planning permission, especially at the front or in conservation areas. Priced per project after survey.
Yes — multiple units fitted in one visit share the access and setup cost, reducing the price per window compared with separate installations.
Free written quotes across Derby and Derbyshire. No obligation, no hidden costs, 10-year guarantee on all work.
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