Velux Roof Window Installation in Basingstoke
Roof repairs, new roofs and roofline work across north Hampshire. Free surveys, fixed written quotes, tidy workmanship.
Basingstoke Roofing Company installs Velux roof windows across Basingstoke — new openings cut into tiled roofs, tired 1990s units swapped for modern ones, and rooflights fitted into flat extension roofs. The roofing side is the part that decides whether it leaks, so it is worth having a roofer do it rather than fitting it around somebody else's carpentry.
There is one thing about Basingstoke housing that changes this job more than anything else, and it is invisible from the street: whether your roof is cut on site or built from trussed rafters.
Trussed roofs change the job
Prefabricated trussed rafters took over British house building from the mid-1960s — exactly when most of Basingstoke was built. A truss is a designed structure: every member and gang-nail plate carries a calculated load, and the diagonal webs are why the roof stands up. Cut one for a window opening and you have not modified a roof, you have removed part of a structure.
That does not mean you cannot have a roof window. Standard Velux sizes are made to fit between rafters at typical 600mm centres, so a window that fits the gap needs no structural work — trimmers above and below the opening, nothing cut. Wider units, or anything that means removing a truss member, need a structural engineer's design and proper support.
Older houses around the town centre, Old Basing and the villages generally have cut roofs with purlins — more freedom, and usually more trimming work.
Windows and the flashing kit that suits your tiles
Centre-pivot windows
The standard unit, rotating on a central hinge. Simplest to fit and easiest to clean from inside. Common sizes run from around 550×980mm to 1140×1180mm.
Top-hung windows
Open outward from the top for a clear view and headroom where the window sits low in the slope. Useful in loft rooms with a low knee wall.
EDW flashing for profiled tiles
The kit for concrete interlocking tiles up to 120mm profile — Marley Ludlow Major, Redland 49 and most of what the estates carry.
EDL flashing for flat coverings
Used with slate, fibre cement and flat-profile tiles up to 16mm. Sits lower and closer to the covering.
BFX underfelt collar
The pleated collar connecting the roofing membrane to the window frame. It keeps water out if the flashing is overtopped, and it is the detail most often left out.
Flat roof rooflights
Kerb-mounted units on extension roofs, with the upstand built and the membrane dressed up and over it.
Installation prices and timescales
| Job | Supplied and fitted | Time |
|---|---|---|
| Velux into a tiled roof, standard size, no structural work | £1,200 – £1,900 | 1 day |
| Second window fitted on the same visit | £900 – £1,500 | Same day |
| Larger unit needing structural trimming | £1,800 – £3,000 | 1–2 days plus design |
| Replace an existing window like for like | £750 – £1,400 | Half a day to a day |
| Flat roof rooflight on a new kerb | £1,400 – £2,600 | 1–2 days |
| Plastered and finished reveals, per window | £300 – £600 | Added to the above |
2026 guide prices including the window, flashing kit, underfelt collar and making good the roof covering. Access equipment is included; decorating is not.
The collar, the reveal and the condensation question
Three details separate a roof window you forget about from one that annoys you every winter. First the BFX collar, which takes the roofing membrane onto the window frame so any water past the flashing still runs out over the tiles. Second, insulation around the frame — packed into the gap between frame and trimmers, because a cold frame in a warm room collects condensation and gets blamed on the seal. Third, the reveals: cut vertical above the window and horizontal below, which throws far more daylight into the room and keeps warm air moving across the glass.
If your existing window mists between the panes, that is a failed sealed unit, not condensation. On a Velux that is often a replacement pane rather than a whole window, provided the frame and the flashing are still sound.
Frequently asked questions
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