Flagship guide · 9 min read
The Ultimate Guide to Aluminium Windows
Everything worth knowing before specifying aluminium windows, from frame construction and thermal performance to colour, glass and realistic pricing.
Guide to Rooflights
How to think about rooflights before you order one: type, placement, glass, ventilation and realistic costs, written as impartial advice.
4 min read
A well-placed rooflight can transform a flat-roofed extension or a dark landing far more effectively than an equivalent wall window, because light from directly overhead travels further into a room. A poorly placed or badly specified one causes overheating, condensation and glare, so the decisions are worth taking seriously before ordering.
This guide is deliberately general rather than tied to a particular product range, because the right rooflight depends heavily on the specific roof, room and orientation involved.
Types of rooflight
| Type | How it works | Best for |
|---|---|---|
| Fixed flat rooflight | Sealed unit, no opening light | Kitchens, hallways, anywhere ventilation is handled elsewhere |
| Opening rooflight (manual or electric) | Hinged or pivoting sash for ventilation | Bathrooms, bedrooms, rooms needing purge ventilation |
| Walk-on rooflight | Structural glass rated for foot traffic | Basement light wells, roof terraces above a room below |
| Sliding rooflight | Panel slides open, larger opening area | Rooms wanting more air movement than a hinged light |
Fixed rooflights are the simplest and most affordable option, and are entirely appropriate where ventilation is already provided elsewhere in the room, for example by windows or mechanical extraction. Opening rooflights add cost and complexity but are often necessary in bathrooms or rooms without another source of purge ventilation under Part F.
Placement, orientation and overheating
The single most common regret with rooflights is overheating in summer, particularly on south-facing single-storey extension roofs with little shading. A large, unshaded rooflight over a kitchen can turn the room uncomfortably hot on a sunny afternoon, regardless of how good the glass is.
- Solar control glass reduces heat gain significantly without a strong tint
- Size the rooflight to the room, not just the ceiling void — bigger is not automatically better
- Consider orientation carefully; north-facing rooflights give even, glare-free light with less overheating risk
- Electric opening rooflights can be linked to a temperature sensor for automatic venting
- External blinds are more effective at reducing heat gain than internal ones, if overheating is a known risk
Glass specification
Rooflights should be double or triple glazed with low-e coatings as standard, and safety glass is required by Part K given the position overhead. Solar control glass is worth considering on any south or west-facing rooflight, and self-cleaning coatings, which use sunlight and rain to break down and wash off dirt, are genuinely useful given how hard rooflights are to reach for cleaning.
- Typical fixed flat rooflight U-value
- 1.0 - 1.4 W/m²K depending on glass
- Safety glazing
- Required under Part K given overhead position
- Self-cleaning coatings
- Reduce maintenance on hard-to-reach roofs
What rooflights cost
As a guide, a fixed flat rooflight of a typical domestic size costs roughly £1,200-£4,000 supplied, before installation, depending on size and glass specification. Opening, electric and walk-on rooflights cost considerably more, and large or structural glazed roof lanterns can run well beyond this range. Installation cost depends heavily on roof access, structural opening work and weatherproofing detail, so always price it as part of the wider project rather than in isolation.
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