What Is a Conservation Rooflight?

The short version in plain words

Most modern roof windows are built to be easy to make and easy to fit. A conservation rooflight is built to be hard to notice. The frame is narrow, the glass is a single clean sheet, and the whole unit sits low against the slates or tiles. Seen from the street, it reads as a small pane in the roof rather than a box on top of it.

The idea comes from the metal roof lights that Victorian and Edwardian builders set into stables, workshops, outbuildings and the back slopes of houses. They were plain, thin and functional. A modern conservation rooflight takes that shape and gives it current glazing, current insulation and a proper weather seal, so you keep the character of the roof and lose the draughts.

People use two words for the same thing. The word on the doorstep is skylight, while the trade says rooflight. Either way, the unit in this answer is the same: a slim opening in a pitched roof, made to disappear into it.

What makes it different from a standard roof window

Four features separate a conservation rooflight from the roof window you would pick off a shelf.

• A slim frame. The metal edge is thin, often steel or aluminium finished to look like steel, so the glass takes up almost all of what you see.
• A low profile. The unit sits close to the roof covering instead of standing proud of it, so it casts less of a shadow line and catches less of the eye.
• A single plane of glass. There are no deep outer casings or wide aprons, and the glazing bars, where they appear, are fine and straight.
• A dark, matt finish. The frame is made to sit in tone with slate, clay or stone slabs, not to contrast with them.

The glass inside is not old-fashioned. It is a sealed, insulated unit with a coating that keeps warmth in the room, and it is laminated on the inside pane so it holds if struck. The old look sits on the outside. The performance is current.

If you want to compare the two in more detail, our guide to choosing a conservation rooflight or a standard roof window sets them side by side.

Where a conservation rooflight belongs

The natural home for one is a pitched roof on a building where the roof is part of the character. That includes cottages and terraces with slate or clay tile, stone-built houses, converted barns and stables, and the rear slopes of older houses where a loft room needs light. It also suits a modern house in a protected setting where the council is likely to look closely at anything that changes the roof.

Around Milton Keynes, that picture covers the older villages and market towns with their own conservation areas, as well as individual listed buildings in the city. Whether your own street falls inside one is a question for the planners at the council. What to look for is set out in our guide to conservation rooflights in conservation areas.

A conservation rooflight is not only for protected places. Some owners simply prefer the clean line of a slim unit, and put one in a plain brick house for that reason. The look is a choice, not a requirement.

How it handles light, heat and weather

The point of any skylight is the light, and a conservation rooflight does the job of a roof window. Straight up is clear. A gable window may face a neighbour's wall or a tree, but the patch of sky above a stair has nothing in the way. A slim rooflight over a stair, landing or loft room fills the space from above, where a gable window cannot reach.

On heat, Approved Document L sets a limit for rooflights in existing homes of 2.2 W/m²K. Modern sealed units meet that comfortably, and solar-control glass can be specified for a south-facing slope so the room does not overheat in summer.

On weather, the unit is fitted into the roof with proper flashings dressed over the slates or tiles, so water runs over the top and away. Condensation and misting are handled by the sealed unit and by good ventilation in the room, not by the frame. Where the rooflight opens, a slim vent or a fixed trickle ventilator can be included, and a blind can be fitted on the inside for evenings and bright afternoons.

What fitting one involves

We start with a free survey, where we look at the roof, the rafters, the inside finish and the view from the street. You then get a fixed written quote that does not change on the day. Building Regulations are met in full, and if the job is notifiable, Building Control is our responsibility. Plastering and decorating prep inside come as part of the job. A 10-year workmanship guarantee is given in writing.

Before a rooflight goes anywhere near a protected building, check the planning position. Our answer on whether conservation rooflights need planning permission covers the route, and the main skylight planning permission guide covers the permitted development rules in full.

You can also read about the way these units sit against the roof, which is the question owners ask most once they have decided on one. For the wider picture, the conservation rooflights hub brings the whole subject together.

Related questions