The glass had failed in six VELUX roof windows at a house in Knutsford, and the windows were around 40 years old. Rather than reglaze them, the homeowner chose to replace all six. Gareth, Steven, Stuart, Martin and Adam removed the old GGL size 7 windows and fitted five VELUX GGU UK04 0070 centre-pivot windows and one GPL UK04 2070 top-hung window, with EW 1000 flashings, underfelt collars and DFD Duo blinds throughout.
Why replace 40-year-old windows rather than reglaze them
When only the sealed glass unit has failed in a sound window, new glass can be the most economical fix. These windows were around 40 years old, though, and failed glass was only the most visible problem. Replacing the whole window meant the homeowner got:
- New glazing all round – VELUX “70” glazing has a 6 mm laminated inner pane and a 4 mm toughened outer pane, with rain-noise reduction and UV protection. It is double glazed, and VELUX rates the GGU 0070 and GPL 2070 at a window U-value of 1.3 W/m²K.
- New frames, seals and hinges – the whole window is new, not just the glass.
- New flashing and an underfelt collar – the weatherproofing around each window is renewed, not just the glass.
- A choice of opening and finish – centre-pivot or top-hung, and white polyurethane or white-painted pine, rather than a copy of the original windows.
Same size, current model: UK04
VELUX has kept its standard sizes while the codes changed. In the current VELUX size range, UK04 is 134 × 98 cm, and VELUX’s size chart lists the older codes 7, 804 and U04 against it. The six openings here took UK04 windows, so the new windows went into the existing openings.
Centre-pivot or top-hung
Five of the new windows are VELUX GGU centre-pivot windows. They open from a bar at the top, so furniture can sit underneath, and the sash rotates for cleaning the outside of the glass. The sixth is a VELUX GPL top-hung window, operated from the bottom and opening outwards for a clearer, more open view.
White polyurethane or white-painted pine
The GGU windows have VELUX’s white polyurethane finish, moulded around a wooden core. VELUX describes it as durable and moisture-resistant, and ideal for humid rooms such as bathrooms and kitchens.
The top-hung window had to be different. As Ivan explains, VELUX doesn’t offer the UK04 top-hung in white polyurethane, only in white-painted pine. VELUX’s UK size chart confirms this: UK04 lists the GGU centre-pivot but, for top-hung, only the GPL. So the top-hung window is a GPL UK04 2070 in pine with a triple-coat white-painted finish, which keeps all six windows white inside.
Flashings and underfelt collars
Each window was fitted with a VELUX EW 1000 flashing. VELUX makes EW for replacing older-generation roof windows while keeping the original installation level and the internal linings, in profiled roofing materials up to 120 mm. The 1000 version comes with a BFX underfelt collar, which closes the gap between the window and the roofing underfelt to create a watertight seal with the battens and underfelt, and includes a drainage gutter that leads water away from the head of the window.
DFD Duo blinds: blackout and pleated
All six windows have a VELUX DFD Duo blind in the UK04 size. Each one combines a blackout roller blind with a white pleated blind, so the homeowner can black a room out for sleep or lower just the pleated layer to soften daylight and add privacy. The photos show both layers in use.
In the photos, the window in the cream room is the GPL top-hung, shown closed with its blind down and then opened up and outwards. The windows in the green, white and grey rooms are the GGU centre-pivot windows.
Our fitting team
The installation was carried out by Gareth, Steven, Stuart, Martin and Adam from our own Skylight Fitters team.
The finished windows
Knutsford VELUX replacement questions
My VELUX window glass has failed. Should I replace the glass or the whole window?
If the frame, seals and hinges are sound, new glass can be the right fix. On windows around 40 years old, as here, the rest of the window has aged too, so a full replacement gives you new glazing, a new frame, new flashing and an underfelt collar.
Will a new VELUX window fit the old opening?
Often, yes. VELUX lists UK04 (134 × 98 cm) as the current size for older windows coded 7, 804 or U04. In Knutsford the six openings took UK04 windows. We check the code on each window’s identification plate before quoting.
Why was one window white-painted pine and not white polyurethane?
The top-hung window is a GPL in white-painted pine. VELUX’s UK size chart lists the UK04 top-hung only as GPL; there is no white polyurethane GPU top-hung in UK04, although the GGU centre-pivot is available in that size.
What is a VELUX DFD Duo blind?
A DFD combines a blackout roller blind with a white pleated blind on the same window. Use the blackout layer for sleep, or the pleated layer to soften daylight and add privacy.
Failed glass in an older VELUX window?
Send us the code from each window’s identification plate, a photo and your postcode. We will tell you whether new glass or a full replacement makes more sense, and which VELUX blinds fit.
More work in and around Knutsford
See our VELUX roof windows in Knutsford page for local house types, conservation areas and the WA16 areas we cover, the Cheshire page, or ask for a free quote.