01Yes, usually
The loft is where most sun tunnels live
Running a tube through a loft is the everyday way to bring daylight into a pitched-roof house, though what is up there decides how easy it is.
If you have a dark landing or bathroom under a pitched roof, the space above it is nearly always a loft, and the tube has to cross that loft to reach the daylight. So can a sun tunnel go through a loft? Yes. It is the most common route there is. The dome sits on the roof slope, the tube passes down through the roof space, and the diffuser fits into the ceiling of the room below.
What changes from house to house is how much is in the way. A tidy, open loft with a clear drop makes for a short, direct run. A loft with a water tank, pipework, a boarded floor or a bedroom wall in the way takes more planning. We look up there on the survey before we promise anything, and we will tell you straight if a route is not sensible.
The roof space is where the tube gets its path, and the survey is where we find out how straight that path can be.
02What is in the way
The things a tube has to get round
Timber, tanks and wiring set the route. A good fitter works with them, not through them.
Pitched roofs are built in one of two ways. Older houses often have cut roofs, with separate rafters and ceiling joists, which leave more freedom to place a tube. Many later houses use trussed rafters, factory-made triangles of timber spaced at regular intervals. Those are engineered, and nothing structural should be cut out of them without a structural engineer's say-so. So the tube has to fit in the gap between two trusses, which is why the width of tube you can choose is often set by the roof, not by what you would like.
Beyond the timber, we check for electrical cables, pipes, extractor ducts and a header tank. Cables and ducts can usually be moved or routed round, though it adds work. Where the tube must bend to dodge something, we use rigid angled sections for the turn, because they lose less light than a flexible tube folded round the same corner. The comparison is spelled out in rigid vs flexible sun tunnels.
- Gap between trusses or rafters wide enough for the tube you want
- A route clear of the water tank, pipes and cables
- No chimney breast or party wall in the line of the tube
- Access into the loft to fit and seal it properly
- A ceiling below that is free of a joist right where the diffuser goes
03Floor and insulation
Boarded lofts and insulation around the tube
A loft you use for storage, or one packed with insulation, can still take a tube. It just asks for a little more care at the ceiling.
Insulation lies on the floor of most lofts, between and over the joists. The tube goes through that layer, and the insulation needs to close back around it, because a gap there is a cold bridge into the room. We also keep the tube clear of anything that would crush it, and on a boarded loft we agree where the board can go so the tube is not walked on or buried under boxes.
If the loft is a habitable space already, say a converted room with plasterboard on the slope, the route is different again. The tube may have to pass through a short boxed section, and you will want a view on the finished look before we start. For a loft room you might prefer a skylight with a view, and roof windows for loft conversions sets out that option. How we keep the tube warm where it crosses cold air is in do sun tunnels make rooms cold.
Open, unused loft
Easiest to survey and fit. The tube can run straight, with insulation closed up around it.
Boarded or converted loft
Needs a planned route and a neat boxed finish, so the tube is protected and still looks tidy.
04On the day
What happens when we fit one through your loft
One team does the roof, the loft and the ceiling, with the floors protected throughout.
The order of work is the same each time, and it matters because the roof is open for the shortest time. For the Building Regulations and planning side, our guides on whether rooflights need Building Regulations and whether sun tunnels need planning permission cover what applies, and we handle any notification that is needed.
- Survey the loft, the roof slope and the room below, and agree the tube size
- Protect the floors and furniture, then mark the position from inside
- Fit the dome and its base on the roof, flashed to the covering
- Run the tube through the loft, sleeve it and close the insulation around it
- Cut the ceiling, fit and seal the diffuser, then clear up
Pipe, joists and insulation: the loft concerns
How long can the tube be through a loft?
Longer runs are possible, but they give you less daylight at the bottom. We keep the run as short and straight as the roof allows. See how much light a sun tunnel gives for what shapes the result.
Will a sun tunnel weaken my roof?
Not when it is planned to sit between the timbers. We do not cut through trussed rafters. If a route would need that, we say so and look for another position or another product.
Can I still use my loft for storage?
Yes. The tube takes up a narrow column, and we can arrange the boarding around it. We just ask that nothing is stacked against the tube or squashes the insulation.
Is a rooflight better than a tube if I have a big loft?
If the loft is a room you use, a window in the slope may suit it better. For a landing or bathroom below an unused loft, a tube is a neat fit. Start with the sun tunnels hub and our guide to how sun tunnels work helps you decide.
