A light tube skylight is one of the simplest ways to bring genuine daylight into a room that has no window at all. It works by capturing sunlight on the roof and channelling it down through a reflective tube into the space below.
This guide by Skylights Roof Lanterns explains how a light tube skylight actually works, where it performs best in a UK home, and how it compares to a traditional rooflight. We'll also cover installation basics, energy savings, and what to check before you buy.
What Is a Light Tube Skylight?
A light tube skylight, also known as a sun tunnel skylight or tubular skylight, is a compact daylighting system rather than a large glazed opening. It captures light at roof level and pipes it straight down into a room through a narrow, highly reflective tube.
Unlike a full rooflight or roof lantern, a light tube skylight does not need major structural work or a large hole in the roof. It suits hallways, bathrooms, and box rooms where a bigger glazed unit simply wouldn't fit or wouldn't be worth the cost. For many UK homeowners, it is the single most effective fix for a permanently dark corner of the house.
How a Light Tube Skylight Works
Every light tube skylight is built from three parts. A weatherproof dome or flat glazing unit sits on the roof and collects daylight. A reflective tube then carries that light down through the loft space. Finally, a diffuser fitted at ceiling level spreads the light evenly into the room.
Because the inside of the tube is coated to reflect light with very little loss, daylight travels efficiently even over longer runs. The full technical breakdown of how this works, including flat and pitched roof fitting kits, is covered in our sun tunnel skylight guide, which is worth a read if you want the finer detail before you commit.
Rigid vs Flexible Light Tube Skylight Tunnels
There are two main tube types used in a light tube skylight installation. A rigid tunnel uses solid, pre-formed sections, and it is the more efficient choice since light travels in a straighter line with fewer reflective losses. A flexible tunnel uses a bendable, ducted tube that can navigate around joists, water tanks, or other loft obstructions.
Choosing between them usually comes down to your loft layout and how far the light has to travel. The table below sets out the main differences.
|
Feature |
Rigid Tunnel |
Flexible Tunnel |
|
Light efficiency |
Higher, due to a straighter light path |
Slightly lower over longer or bent runs |
|
Best suited to |
Short, straight roof-to-ceiling runs |
Runs that need to navigate joists or obstructions |
|
Installation |
Slightly more involved, precise cutting required |
Generally quicker and easier to fit |
|
Typical use case |
Bathrooms and hallways directly under the roof |
Rooms set further back from the roofline |
|
Flexibility around obstacles |
Limited, needs a clear line |
High, can bend around loft obstructions |
Where a Light Tube Skylight Works Best
A light tube skylight tends to have the biggest visible impact in rooms that were never designed to receive daylight in the first place. Internal hallways, downstairs WCs, walk-in wardrobes, and utility rooms are the classic candidates.
These are the spots where a light tube skylight makes the most sense:
- Windowless hallways and landings that rely on a bulb even at midday
- Downstairs bathrooms without an external wall for ventilation windows
- Walk-in wardrobes and storage rooms too small for a full rooflight
- Utility rooms tucked at the back of the property
- Under-stair cupboards converted into small home offices
Browsing our skylights collection is a useful next step once you've identified the room, since it lets you compare specifications side by side before deciding on a fitting.
Light Tube Skylight vs Traditional Rooflights
A light tube skylight and a full-size rooflight solve different problems, so the choice usually comes down to the room itself. A rooflight or roof lantern makes sense where you want a bigger opening, a view of the sky, or ventilation as well as light.
A light tube skylight, by contrast, is built specifically for small or awkward spaces where a large glazed unit isn't practical. Its narrow roof footprint means less disruption to the wider roof structure and fewer thermal considerations to plan around.
If your room has more flexibility on roof access, it's worth comparing against our flat rooflights collection to see whether a larger glazed unit might actually suit the space better, particularly if you also want ventilation.
Installation Considerations for a Light Tube Skylight
Before ordering, there are a few practical checks worth making. Roof type and pitch matter, since flat and pitched roofs use different fixing kits and flashing details.
Distance from roof to ceiling is another key factor. Shorter, straighter runs generally favour a rigid tunnel for maximum light output, while longer or obstructed runs usually call for a flexible system instead.
Room size also plays a part. A single light tube skylight is typically sized to light a small or medium room effectively, so larger open-plan spaces may need more than one unit. For loft-based or pitched roof properties, our overview of pitched roof windows is a useful companion read, since many of the same fixing principles apply.
Energy Efficiency and Planning Permission
A light tube skylight can meaningfully cut how much artificial lighting a room needs during the day. Government research into UK household lighting patterns has found that households with poor access to daylight tend to leave lights on for longer during daytime hours, according to the Household Electricity Survey lighting report published by the Department for Business, Energy and Industrial Strategy.
On the planning side, most light tube skylight installations fall under permitted development, so a separate planning application usually isn't required. Also, roof alterations of this kind are covered as long as certain height and projection limits are respected. It's still worth checking with your local authority first, particularly for listed buildings or conservation areas.
Good daylight also supports better indoor air quality when paired with proper airflow. If ventilation is a wider concern in your home, our guide on improving poor ventilation at home covers practical steps alongside daylighting upgrades like a light tube skylight.
Choosing the Right Light Tube Skylight for Your Property
Getting the size and tunnel type right matters more than most people expect. A light tube skylight that's too small for the room will disappoint, while an oversized unit in a tight loft space can be hard to fit cleanly.
If your loft has a straightforward, short run from roof to ceiling, a rigid tunnel light tube skylight will usually give you the brightest result. Where the loft is more cluttered, or the room sits further back from the roofline, a flexible tunnel is the more practical choice.
For lofts and pitched roof conversions where you might want a mix of tube skylights and larger glazing, our roof windows collection is worth browsing alongside your light tube skylight plans, particularly if the space could accommodate both.
Final Thoughts
A light tube skylight is a genuinely practical way to solve the problem of a permanently dark room without major building work. Whether you choose a rigid or flexible tunnel comes down to your loft layout and how far the light needs to travel. Get the sizing and tunnel type right, and even the darkest hallway or bathroom can feel naturally bright throughout the day.
If you'd like advice on which light tube skylight suits your property, get a quote from our team or call 0204 538 3079. We're happy to talk through the options before you buy.
