The short answer
A solid conservatory roof can include roof windows or rooflights, and they restore much of the daylight a glazed roof gave. They are built into the roof design, so they are best planned before the roof is made. Building Regulations apply, with thermal limits for each type, and a conservation area or listed building adds planning checks.
Why people add light back into a solid roof
A tiled or insulated solid roof fixes the two most common complaints about a glazed conservatory: it overheats in summer and it is cold in winter. The price is a darker room. A space that used to be flooded with light now has walls on three sides and a ceiling that gives nothing back.
Skylights answer that. A well-placed pair can brighten a room far more than their small area suggests, because light arrives from above and bounces around a pale ceiling. They can also release hot air, which matters because a solid roof alone does not remove the heat that builds up behind the glass walls. Our page on the hot conservatory problem looks at that side of things.
Roof window or rooflight: which is which
The two words are often used loosely, but the building rules treat them differently. A roof window is an openable window set into the plane of a pitched roof, like the familiar loft window. A rooflight is a fixed or flat glazed unit, often a glass lantern or a flat panel, set on a kerb on a low-pitched or flat roof.
The distinction matters because Part L of the Building Regulations sets a different limit for each. Table 4.2 of Approved Document L sets the figures for new or replacement parts of an existing dwelling. Roof windows face the tighter limit, and rooflights a more relaxed one, so a roof window in a conservatory roof has the harder target to meet.
Most solid conservatory roofs are pitched, so roof windows are usually the natural choice. A lantern suits a flat or very shallow roof, and the kerb it sits on is part of the thermal calculation, with any upstand built on site limited to 0.35 W/m²K.
Where they go and how many
Position is easier to settle before the roof goes on. The rafters or purlins that carry the roof run at set spacings, and a window frame has to fit between them or the structure has to be trimmed around it. Trimming adds timber and steel, and it adds cost. Planning the opening from the start avoids that.
On a lean-to the best light often comes from the upper part of the slope, close to the house wall, where it stays clear of the glazed walls and reflects off the ceiling. On a gable or Victorian shape, a pair of windows either side of the ridge tends to look balanced from inside. We also take into account where the sun falls across the day, since south-facing glass will lift the temperature again.
Our page on lean-to conservatory roofs shows how the pitch affects what can be fitted, and the conservatory roof vent page explains how an opening roof window helps with airflow.
Cost and the structural bit
National price guides give an idea of the scale. MyBuilder's conservatory roof guide, updated in August 2026, gives solid conservatory roofs at £5,000 to £10,000, with structural reinforcement at £500 to £2,000. Its roof window guide puts a standard fitting at £350 to £600 for labour and fitting, with scaffolding at around £500. These are national figures for separate jobs, not our prices, and a window fitted as part of a new roof is different in kind from one cut into an existing roof.
The structural point is the one to take seriously. A solid roof is heavier than glazing, and every opening means the load has to be carried round it. Homebuilding & Renovating points out that an old conservatory frame must take more weight once a solid roof goes on, so the frame is checked before any decision on windows. Our conservatory internal ceiling page explains what finishes the underside of the roof.
Building Regulations and planning
A solid replacement roof needs a building control application, and a skylight is simply part of that design, so one application covers both. The Planning Portal expects a new conservatory roof to be safe, energy efficient and well ventilated, and treats most roof alterations as permitted development inside the limits.
Two limits are worth knowing. Under Class C, a roof window may not stand more than 0.15 metres proud of the roof plane, and nothing may sit higher than the original ridge line. Any window on a side-facing slope has to be obscure-glazed. Conservatories are usually at the rear of a house, where a side-facing slope may still exist on a corner plot or against a boundary.
For a listed building or a conservation area, ask the planning team at Swindon Borough Council, or your own council, before you order anything. Consent is explained at survey, and where the job is notifiable we handle the Building Regulations notification.
What to decide before the survey
A few answers make the survey quicker. Is the room used mostly in the morning or the evening? Does it need to go dark for the television? Do you want windows that open or fixed glass? Is there a plan for shade on the brightest days? Our guide to conservatory roof blinds covers that last point, since roof windows often take blinds made for them.
On the visit we photograph the frame, the old roof and the way the sun moves across the room, and the quote that comes afterwards describes the roof and its openings together. The wider project is outlined on the conservatory roof replacement page. Sometimes one vent window in an existing roof is all the room needs, and then that is the job we put forward.