The short answer
They do, when the run from roof to ceiling is short and fairly straight and the room is small. A sun tunnel gives a windowless space a soft pool of daylight, and it does so with a roof opening far smaller than a rooflight needs. It will not give a view, it will not open for air, and it struggles to light a large room or one at the far end of a long, bending tube.
- Free survey, fixed written quote
- 10-year workmanship guarantee
What working means for a tube
The test is simple: can you read a label, find a sock or shave without touching the switch on an ordinary day? In a small room with a short run above it, the answer is usually yes. Light enters the dome, travels down the mirrored lining and spreads from the diffuser across the ceiling and walls.
The amount you get depends on the sky. A bright day gives strong light, a grey one less, and a dark winter afternoon very little. That is the same for any daylight source, but a tube has no side window to help, so the dip is more obvious. Keep the ceiling light, and think of the tube as your daytime light.
Season changes the picture too. In June the sun stands high and the dome catches it for hours. In December the sun is low and the day is short, so the light at the ceiling is gentler and fades earlier. A room used mainly in the evening, such as a utility with a washing line, gets less from a tube than a cloakroom visited all day.
Where they fall short
A tube disappoints in a handful of situations, and we can usually see them from the loft. A very long run, or one with several elbows, loses much of the light before it reaches the room. A big room asks one diffuser to do the job of a whole window. A dome that sits in the shade of a chimney stack or a neighbour's gable collects less to begin with.
Moss, leaf litter and bird droppings on the dome do the same thing slowly. A rinse from a ladder or a long pole on a dry day brings the brightness back. Whether the dome can be reached safely from a ladder or needs other access is something we judge on the roof at survey.
One more thing to expect is the colour of the light. A diffuser throws neutral daylight, so a cloakroom looks different under it than under a warm bulb, and paint and towels show their true colour in the morning.
A dark painted room soaks up what does arrive. A pantry with charcoal walls is a good example: the same tube that brightens a pale cloakroom leaves it dim. When these conditions stack up, a sun tunnel is the wrong tool, and the survey shows which product would do better.
| Situation | Likely result |
|---|---|
| Small room, short straight run, pale decoration | Good daylight through the day |
| Long run with elbows | Noticeably dimmer at the ceiling |
| Large room | One diffuser covers only part of the floor |
| Dome shaded by a chimney or neighbouring gable | Less light enters in the first place |
Heat, damp and the roof opening
A tube cuts a much smaller hole in the roof than a rooflight, so there is less glass to lose heat from. The diffuser at the ceiling and the sealed joint around it are there to keep warm air from the room away from the cold tube, and we check the seal and the insulation around the tube as part of the job. A new opening in a roof is building work, and we handle the Building Control notification where it is notifiable.
On a flat roof the dome sits on a small upstand finished into the covering. On tile and slate it sits in a flashing matched to the roof. Both are detailed at survey, as the hub page on sun tunnels sets out.
Myth
A sun tunnel is the same as a small skylight and gives the same light.
Fact
A tube delivers diffused light to one point on the ceiling. A rooflight or roof window opens a patch of sky above the room and lights a wider area.
When something else does the job better
If the room is a loft bedroom or a study in the roof, a roof window gives a view and opens for air. If the space is a deep extension under a flat roof, a flat roof rooflight lights a wider area than one tube can. Where only a small windowless room needs light, a tube is often the simplest answer, with the least disruption to the roof.
The detail on routes is in rigid or flexible sun tunnels and tube length limits. Price depends on the length and route of the tube, the roof covering and how easy the loft is to reach, and sun tunnel cost goes through those. To have your own room checked, book a free survey; the fixed written quote follows it.
