Installing a Sun Tunnel

Summary: Information on what a sun tunnel is and how to install a sun tunnel to bring natural light in to a building

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Sometimes called sky tunnel & sun tubes, they can be installed into most roof structures, but you might struggle with a thatched roof. Any feed back from anyone who has attempted this would be most welcome.

Sunlight is guided down a shiny tunnel into an area which would previously only have been lit with high energy bulb lighting.

Cross section of a roof showing sun tunnel pipeworkSun tunnels are becoming increasingly popular with the green movement as these installations do not use any extra energy to create more light. Natural energy from the sun is all that is required.

Sun tunnels consist of a roof dome connected to flexible or rigid reflective tubing down to an internal display lighting unit with fittings. Costs will vary with size, style and manufacture.

A sun tunnel will provide the equivalent amount of power in the following sizes:

  • 10 inch sun tunnel = 150 – 200 watts
  • 14 inch sun tunnel = 250 – 300 watts

They are extremely capable of working over reasonably long distances up to 30ft; also an existing light fitting can be incorporated into the sun tunnel for night use. The light reflecting tunnel tubing can be bought in flexible or rigid forms depending how you need to use it.


Your sun tunnel installation depends to a degree on the siting of your roof trusses, rafters and joists. While these can of course be moved, it is considerably cheaper to work round their existing positions. A good survey is recommended. You should also check for any cabling / plumbing pipe work that may be in the ceiling void above where you are going to cut.

Sun tunnel kits come with templates for cutting out holes in the roof and ceilings. Fixing brackets are also supplied for the reflective tubing. Holes should be cut in accordance with manufacturer’s instructions. This usually means cutting all internal holes first and disturbing the main roof structure last. Remember to use eye protection because a lot of dust and debris may be in your ceiling void and this will fall through when completing this part of the installation process.

When you have completed this part of the process you can move to the roof section of work.

Roofing Work

If your roof is a pitched roof above you will need to take safety precautions for access i.e. the use of scaffolding to provide a safe working platform. Roof ladders are usually required also. These can be hired from the local tool hire shop.

The dome in the roof will require timber bracing to hold it in place and care must be taken not to compromise the integrity of the roof. Do not remove any timber in the roof unless instructed to by an architect or building surveyor.

The part of the sun tunnel that is built into your roof is the flashing kit which protects the opening against rainwater penetration. When the flashing kit is in place the sun dome can be placed and fixed. If the distance between the roof flashing and the ceiling manifold is less than 3m you can allow your sun tunnel tubing simply to hang and be connected to the ceiling manifold. If the tube is longer than this, bracing (by means of internal timber work) may be required. Before bracing, pull your Sun Tunnel tubing tight to the ceiling manifold and remove excess length.

Once this has been done you can connect the tubing to your ceiling manifold (Internal tunnel light fitting) with the appropriate parts of your installation kit. You can then complete your installation with the inserting of your diffuser to your ceiling manifold.

The diffuser splits the light into segments which make it easier to manage in the room and avoids shafts of sunlight hitting one spot.

As always with work that creates debris, dust and the use of sharp components DIY Doctor recommends the use of gloves, dust masks and eye protection.

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