Sun Tunnel or Skylight: Which Suits the Space?

A sun tunnel is a dome on the roof, a reflective tube through the loft and a diffuser in the ceiling. It carries daylight, and nothing else, to a spot that could not otherwise be reached. The diffuser is frosted, so there is no view.

A skylight is the homeowner's word for glass in the roof. The trade says rooflight for a fixed or flat unit and roof window for one set in a pitched roof, such as a VELUX. These put a pane of glass directly over the room, so you see the sky, and many open for air.

The difference is the path. A tunnel moves light along a tube, losing some on the way. A skylight lets light straight in through the glass. That single fact explains most of what follows.

Think about the spot first. A landing, a windowless bathroom, a cloakroom or a narrow hall is a small space where a tunnel does the job. The diffuser sits above the spot, the daylight lands where you stand and the roof opening is small.

A kitchen, a living room, a loft bedroom or a home office is a larger space, or one where you spend hours. There you want more light, and often a view of the sky and a way to open the unit for air. A roof window on a pitched roof or a flat rooflight on an extension is the better fit. For a wide kitchen extension, a roof lantern may be the answer.

Some houses use both. A roof window lights the loft bedroom, and a tunnel lights the landing below it. They do not compete, because they solve different problems.

Budget and disruption also shape the choice. A tunnel's small openings mean less mess in the loft and on the ceiling, and a tidy finish. A larger skylight is a bigger project but gives a bigger return in light and outlook. Neither is better in the abstract. Each is better for a particular spot.

A tunnel needs a loft above the space, because the tube has to run through it. A skylight does not, which makes it the answer for a vaulted ceiling or a room directly under the roof slope. If the space has a floor above it, a tunnel is ruled out and a skylight in a different place may be the answer.

Both usually fall within permitted development on a house, which has conditions. Our planning guide lists the conditions. Flats, listed buildings and conservation areas add checks of their own. Where the work is notifiable, the Building Control notification is ours to handle, and the finished work meets the Regulations as they stand.

A tunnel's roof and ceiling openings are small, which can make it the easier job. A skylight is a larger opening, so it takes more structural work. The free survey weighs these points against what you want.

Take a bathroom with no window on the top floor, a loft bedroom with a sloping ceiling and a kitchen extension with a flat roof. The bathroom wants private daylight with a loft overhead, which is a tunnel. The bedroom has no loft above its slope, wants air and a view, and suits a roof window. The extension wants plenty of light across a worktop and table, and suits a flat rooflight or a lantern.

That is the pattern. Look at what the space needs, then match the product. A tunnel is a precise tool for a small job, and a skylight is a broader one. If your house has both kinds of space, there is no reason to choose only one.

Replacing what is there

If you already have a tunnel and the room feels dim, a skylight in a better position is sometimes the fix. If you have an old rooflight that leaks or has misted, replacing it with a new unit may be all that is needed. The survey looks at the whole picture before recommending either.

Ask three questions. Is the space small and internal? Is there a loft directly above? Do you need only light, with no view or opening? Three yes answers point to a tunnel. A no to any of them points to a skylight.

If you cannot decide, the free survey will do it, and the quote after it is written and fixed. We look at the spot, the loft and the roof, and we tell you which product gives the better light. Use the survey form to start. Our sun tunnels guide covers tunnels in full, and are sun tunnels a good idea gives the wider balance of pros and cons.