Essential design guide to rooflights

Bring natural light into your loft conversion or extended living space with the right roof window. Michael Holmes explains what you should look for and offers his advice on rooflights, rooflanterns and conservation rooflights, as well as some useful tips on building regulations and planning requirements

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Rooflights, also known as roof windows or skylights, give you the opportunity to bring in daylight through a flat or sloped roof. They’re ideal for loft areas, rooms with vaulted sloping ceilings, and conversions of protected buildings such as barns, where new window openings in the walls are often not allowed. This is partly because rooflights have less visual impact from the outside, and in planning terms they’re not considered to overlook neighbouring properties as windows do, so planning permission is often not required (see below for further advice on planning permission).

A rooflight can bring in up to 40 per cent more light than the alternative form of roof window, the dormer, and is substantially less expensive to install.

Whether you’re extending or renovating in a traditional or modern style, there is a roof window option to suit the design of your home.

Who should install them?

Fitting a rooflight can be tackled by a skilled DIYer with carpentry skills. For anyone else, it is best left to the professionals. In an extension, they should be fitted after the roof is constructed. Where a rooflight is being fitted into an existing roof, it will usually be installed at first fix stage, before the walls and roof are insulated.

Design options

Roof lanterns

Another option, which can be fitted to a flat roof or along the ridge of a pitched roof, is a roof lantern or ridgelight. Similar to a small conservatory structure, the frames are usually constructed of timber or powdercoated steel, although metal-reinforced PVC is also available.

Options include gable-ended and hipped-gable roof lanterns — these can include opening elements if required.

Fire escape windows

In a loft conversion above a bungalow, the structure and stairway don’t have to be upgraded to give half an hour of fire protection for fire safety, providing all habitable rooms in the roof are fitted with a fire escape/egress window. A fire escape rooflight can meet this Building Regulations requirement, as long as it has a clear opening space measuring at least 450mm by 450mm. Most ranges include fire escape models.

Electronic control

Where you can’t reach a rooflight to open it manually, you can choose to control it automatically. Many manufacturers have developed units for their windows, operated by a wall-mounted or handheld remote control. They often include a sensor to close the window automatically if it starts to rain.

Flat roof options

There are several rooflight choices for a flat roof, ranging from domes, pyramids and arches to straightforward flat rooflights. All units can combine opening elements, either hinged or sliding. For a contemporary look, there are frameless options where the frame is completely obscured from below so only the glazing is visible. Larger openings may need a structural bar to support two or more double-glazed units. This can be made from structural glass.

Conservation rooflights

On a listed building, in a conservation area, or on a converted traditional building, such as a barn, local authority planners will usually insist on conservation rooflights. These sit flush, so they’re more discreet.

The original 19th-century rooflight frames were made from cast iron and single-glazed. Today’s version is more energy-efficient, with a thermally broken steel frame and low-e double-glazed units.

There are many standard sizes available, with larger units divided vertically into separate panes. Bespoke sizes can also be made if standard measurements are not suitable. The standard colour for metal rooflights is black, but it is possible to order any colour from the RAL range.

Structural glass

The entire area of a small flat roof could be constructed using double-glazed units, either on a metal framework or on structural glass beams. This creates a very minimal look, which can work well with contemporary interiors and as part of a link on a listed building.

Feature styles

A number of standard or bespoke rooflights can be combined to create a feature window. Typically this will be a bank of several rooflights in a single roof plane, arranged in a symmetrical pattern, separated only by the timber rafters, or steelwork if required. Skylights can also be fitted either side of the ridge in a pitched roof, creating a roof lantern effect.

Timber-framed designs

The standard off-the-shelf rooflight has a timber frame with low-e double glazing, and is pivot-hinged at the vertical centre to balance the weight and make it easy to open and close. It is designed with a built-in open and close vent for background ventilation to meet Building Regulations. Flashing kits are usually sold separately to suit slate, clay tiles and other roof coverings.

There is an extensive range of standard dimensions, designed to suit typical rafter widths, but bespoke sizes can be ordered. Clad in grey aluminium on the outside, the usual finish is stained timber on the inside, although VELUX also offers it in white.

Planning rules

In England and Wales, you don’t normally need to apply for planning permission to alter your roof to fit rooflights, providing the work constitutes permitted development (PD) — see for full details. In brief, you’re unlikely to need planning permission for rooflights unless:

  • a proposed skylight installation occupies a large area of your roof beyond what is considered a ‘reasonable’ size;
  • a skylight projects beyond the roof plane by more than 150mm;
  • you live in a listed building or a designated area, such as a National Park or conservation area;
  • a so-called Article 4 Direction, or other planning condition, is in place for the area you live in. This will require you to submit an application, even if the work wouldn’t need it elsewhere.

New PD rights in Scotland mean rooflights on an existing house or flat won’t usually require permission.