Velux windows and roof lanterns are both ways of bringing natural light into a room through the roof, but they are fundamentally different products designed for different situations. Choosing the wrong one creates planning problems, structural complications or simply the wrong result for the space. This guide explains the honest difference.
A Velux roof window sits flush in a pitched roof and costs 600-900 pounds installed. A roof lantern is a raised glazed structure for flat roofs, costing 2,500-5,000 pounds. They suit different roof types — installing the wrong one creates structural or planning problems.
A Velux window (more accurately, a roof window) is a factory-made unit that sits flush within the existing roof plane. It replaces a small section of the tile or slate covering, is flashed with a product-specific kit, and requires minimal structural alteration to the existing roof.
A roof lantern is a glazed structure that sits on top of a flat roof, typically on an extension. It rises above the flat roof surface, creating a raised glazed element that allows light into the room below. Roof lanterns require an opening in the flat roof structure and are often part of a flat-roof extension design rather than an afterthought.
Velux window installation on a pitched roof slope that does not face the highway is generally permitted development in most of Exeter. The standard conditions apply: not on the principal elevation, not protruding more than 150mm above the roof plane.
The Town and Country Planning (General Permitted Development) Order 2015 permits most roof window installations on non-principal elevations without planning permission.
Source: GPDO 2015
Roof lanterns on flat-roof extensions are generally permitted development if the extension itself was permitted development and the lantern does not exceed the height or footprint permitted for additions. In practice, most domestic roof lantern installations on standard Exeter extensions are permitted.
Both become more complex on conservation area properties and listed buildings, where prior notification or listed building consent may be required. Exeter's extensive conservation area coverage affects properties in the city centre, parts of Heavitree and all of Topsham.
A Velux window installed by a Devon roofer costs £600–£900 per window including supply, fit and flashing. The cost is predictable because the window size, model and flashing type are standardised.
A roof lantern installation is more variable because the cost depends on: the lantern size and specification; whether the flat roof structure requires reinforcement to carry the lantern frame; whether the flat roof covering needs to be cut and reformed around the opening; and finishing of the internal reveal.
A standard domestic roof lantern installation in Exeter — 1200mm x 800mm unit, standard height, on an existing sound flat roof — typically costs £2,500–£5,000 including the lantern unit, structural opening, flat roof re-detailing and internal finishing.
For the same floor area of glazing, a roof lantern costs approximately 3–4x the cost of an equivalent Velux installation.
Considering a Velux window or roof lantern on your Exeter property? Free survey and honest recommendation. Call 01392 759 295.
📞 Call 01392 759 295A Velux window is the right choice when: the existing roof is a pitched roof with an accessible loft space; the primary goal is to add light to a loft room or landing; the budget is constrained; and the planning position is straightforward.
A roof lantern is the right choice when: the property has a flat-roof extension and the room below needs central overhead light; the design intent is an architectural feature as well as a light source; and the extension was designed with a lantern in mind (or the flat roof structure is appropriate for one).
Installing a roof lantern on a pitched roof or a Velux on a flat roof creates either structural complications or aesthetic problems. The products are designed for different roof types and should be matched accordingly.
We install Velux windows across all roof types in Exeter and Devon. For roof lanterns, we work with specialist glazing installers and can manage the full project including the flat roof detailing around the lantern opening.
For any Exeter property considering roof glazing, we carry out a free survey that confirms the correct product for the roof type, advises on the planning position, and provides a fixed price for the roofing element of the installation.
“Velux on our Victorian loft conversion. Conservation flashing specified for the slate. Planning position confirmed. Excellent result.”
“They advised against a roof lantern on the roof type we had. Correct Velux recommendation instead. Saved us significant cost.”
“Two Velux windows installed on a standard 1970s semi. Half a day. Fully weathertight. Very pleased.”
A Velux window sits flush in a pitched roof plane. A roof lantern is a raised glazed structure on a flat roof. They are designed for different roof types and situations.
£600–£900 per window including supply, fit and flashing. Free survey. Call 01392 759 295.
£2,500–£5,000 for a standard domestic installation including structure, roofing detailing and internal finishing.
Generally no for non-principal elevations. Conservation area and listed properties require prior notification or consent. We advise at survey.
Roof lanterns are designed for flat roofs. A pitched roof requires a Velux window or a dormer window, not a lantern.
For modest light requirements, Velux is the simpler and more cost-effective solution. A dormer provides more headroom and floor space but requires structural work and planning permission.
Yes — we install across Exeter and all Devon coverage areas. Call 01392 759 295 for a free survey.
No call-out fee. No obligation. Local Devon roofers who turn up when they say they will.
01392 759 295Last reviewed: 21 July 2026
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