Flat roof skylights are becoming increasingly popular on extensions and single-storey additions across Grays. They bring natural light into rooms that would otherwise rely entirely on side windows or artificial lighting. We install fixed and opening models from Velux, Fakro, and specialist manufacturers — properly trimmed into the roof structure and flashed to keep everything watertight.
Skylight installation involves several key steps: choosing the right window type and size, cutting an opening in the roof structure, properly trimming the rafters to support the frame, installing the window unit, fitting the correct flashing kit for your roof covering, and finishing the internal reveals. We primarily install Velux and Fakro roof windows — both are excellent products with good warranties and readily available accessories. Velux models range from the GPU centre-pivot (the most popular) to the GGL top-hung, the GDL Cabrio balcony window, and the CFP fixed flat roof skylight. Sizes are standardised — CK02 (55x78cm) for small spaces, MK04 (78x98cm) for standard rooms, SK06 (114x118cm) for maximum light, and larger. The structural trimming is critical: where a rafter falls in the middle of the window opening, it needs cutting and the load transferred to trimmer joists on either side. This is structural work and needs to be done properly. The flashing kit must match both the window model and your roof covering — slate, profiled tile, flat tile, or flat roof each need a different kit. For properties in Grays, where a Thames-side town in Thurrock, Essex, with a mix of Victorian terraces, inter-war housing, and modern waterfront developments often exposed to river winds, we select windows and flashing appropriate to the specific roof type and exposure.
The most common cause of a leaking skylight isn't the window itself — it's the flashing around it. If the wrong flashing kit was used, if it wasn't fitted correctly, or if it's simply old and deteriorated, water gets in around the frame. We see this regularly across Essex. The fix is usually a new flashing kit rather than a whole new window.
If your skylight has a white fog between the glass panes that you can't wipe away, the seal between the panes has failed. This is common on older units, particularly those from before 2000. The glass unit can sometimes be replaced separately, but on older Velux models it's often more practical to replace the whole window — you get better insulation and a modern look as part of the deal.
We occasionally come across skylights that have been installed without proper trimmer joists — the rafters were just cut and the window wedged in. This weakens the roof structure and can cause the window frame to distort over time, leading to operating problems and leaks. If your skylight was fitted by a general builder rather than a roofing specialist, it's worth having the trimming checked.
Velux and Fakro make different flashing kits for different roof coverings — EDW for profiled tiles, EDP for plain tiles, EDL for slate. Using the wrong one is a recipe for leaks. It sounds obvious, but we see it regularly — a slate flashing kit used on a tiled roof, or a tile kit forced to fit on flat tiles. The fix is straightforward: remove the wrong kit and fit the right one.
A single Velux centre-pivot skylight, supplied and fitted into an existing tiled roof in Grays, typically costs £800-£1,500 depending on size. A pair of windows side by side runs £1,400-£2,400. Larger sizes and premium models (electric opening, rain sensors, top-hung) cost more — a Velux Integra electric window is roughly £200-£400 extra over the manual equivalent. Flat roof skylights start from £1,000-£2,000 fitted. Sun tunnels — flexible tubes that bring light into rooms without direct roof access — are £500-£900. Replacement of an existing old skylight with a new one in the same opening costs £600-£1,000 including new flashing. Internal finishing (plasterboard reveals, decoration) is separate and depends on the finish you want. Scaffolding, if needed for access, adds £400-£800.
Windows: Velux GPU (centre-pivot, white polyurethane coated, double glazed, argon filled) as standard; GGL (top-hung) and GDL Cabrio as options. Fakro FTT, FTP, and FPP models as alternatives. Flat roof: Velux CFP fixed and CVP opening. Flashing kits: Velux EDW (profiled tile), EDP (plain tile), EDL (slate), EDN (flat roof). Structural trimming: C24 graded structural timber for trimmer joists and cripple rafters, fixed with joist hangers (Simpson Strong-Tie) or bolted connections. Insulation: Celotex or Kingspan rigid PIR around the window frame to prevent cold bridging. Internal finishing: moisture-resistant plasterboard for reveals, with insulation-backed board where needed.
We visit your Grays property, look at the roof from outside and the room from inside, and help you choose the right window size, type, and position. We check for any structural or planning considerations and give you a clear quote.
From inside the loft, we mark out the opening and install trimmer joists to support the cut rafters. This transfers the roof load properly around the new opening. All structural timber is C24 graded and fixed with appropriate connectors.
The roof covering is carefully opened from outside, the frame is fitted and levelled, and the window unit is secured. The correct flashing kit is installed, integrating the window seamlessly with the surrounding tiles or slates.
Every flashing joint is checked and sealed. Surrounding tiles are refitted to their original positions. The window is opened and closed to confirm smooth operation. Insulation is packed around the frame to prevent cold bridging.
If required, we form and plaster the internal reveals — angling them to maximise the light spread into the room. This is an optional extra but makes a big difference to the finished appearance and light distribution.
Skylights are a popular addition to properties across Grays, particularly in loft conversions and top-floor bathroom renovations. Grays is a Thames-side town in Thurrock, Essex, with a mix of Victorian terraces, inter-war housing, and modern waterfront developments often exposed to river winds. The existing roof covering dictates the flashing kit needed — concrete interlocking tiles (common on post-war properties) use the EDW kit, while older properties with plain tiles or slate need the EDP or EDL kit respectively. Planning permission is generally not needed for skylights under Permitted Development Part 1 Class C, provided the window doesn't protrude more than 150mm from the roof slope and doesn't face a highway on certain property types. However, in conservation areas across Essex, there may be additional restrictions on the position and size of skylights — we'll check this for you.
We approach skylight installation from the roof side — getting the flashing and weatherproofing absolutely right. That's the part that matters most and the part that general builders most commonly get wrong.
Tile, slate, flat — we've fitted skylights into every type of roof across Essex and we carry the correct flashing kits for each. No guesswork, no wrong kit, no leaks.
Every skylight opening is properly trimmed with graded structural timber. We don't just cut rafters and hope — the load is transferred correctly around the opening.
We work with both major brands and know their product ranges inside out. We'll recommend the right model for your situation rather than just fitting whatever's in stock.
Usually no. Skylights are permitted development under Part 1, Class C, provided the window doesn't protrude more than 150mm above the roof slope. There are restrictions in conservation areas and on listed buildings — and on some property types, the window mustn't face a highway. We'll check the specifics for your property before going ahead.
A single standard Velux centre-pivot window, supplied and fitted with the correct flashing kit, costs £800-£1,500 depending on size. A pair side by side runs £1,400-£2,400. Electric models add £200-£400 per window. Flat roof skylights are £1,000-£2,000. These prices include the structural trimming but not internal plasterwork, which is quoted separately.
A single skylight installation into an existing roof typically takes one day. A pair takes one to two days. If the loft space needs insulation work or structural modification beyond standard trimming, it might take a bit longer. Internal plastering and decoration — if we're doing that too — adds another day.
It can get warm, but there are solutions. Velux and Fakro both offer blinds — blackout, heat-reducing, and venetian options. External awning blinds are the most effective at keeping heat out. The opening function of the skylight also helps — hot air rises, so an open roof window at the highest point is very effective at venting warm air out of the room.
Yes — we install flat roof skylights from Velux and other manufacturers into flat-roofed extensions, kitchens, and single-storey additions. These sit in a kerb on the flat roof surface, available as fixed or opening, and they bring a huge amount of natural light into rooms that might otherwise be quite dark.
Not necessarily. Most skylight leaks are caused by failed or incorrect flashing, not the window itself. We'll check whether a new flashing kit will solve the problem — it often does, and it's much cheaper than a full replacement. If the window unit itself is old, has failed seals (fog between the panes), or is physically damaged, then replacement is the better option.
It depends on the room size and how much light you want. As a rough guide: CK02 (55x78cm) suits small bathrooms and stairwells; MK04 (78x98cm) is the most popular size for bedrooms and living spaces; SK06 (114x118cm) gives maximum light for larger rooms. We'll measure the rafter spacing and recommend the largest window that fits between or across the rafters.
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