How Much Does a Sun Tunnel Cost in 2026? (UK)
A sun tunnel costs between £500 and £1,800 fully fitted in 2026. Rigid-tube 250mm units sit at the bottom of the range (£500–£900 fitted), flexible 350mm units come in at £700–£1,200, and electric-powered models with integrated LED for hallways and stairwells run £1,200–£1,800. That is a fraction of a roof light — typically £2,500–£5,000 fitted — and a far cheaper way to bring natural daylight into a windowless bathroom, en-suite, landing or walk-in wardrobe. Here is the full cost breakdown, the four factors that move the price, and the cases where a roof light is the better spend.
2026 sun tunnel cost breakdown
| Type | Diameter | Fitted price | Light output |
|---|---|---|---|
| Rigid sun tunnel | 250mm (10") | £500–£900 | Equivalent to a 60W bulb |
| Rigid sun tunnel | 350mm (14") | £700–£1,100 | Equivalent to a 100W bulb |
| Flexible sun tunnel | 250mm (10") | £550–£950 | ~70% of rigid (bends lose light) |
| Flexible sun tunnel | 350mm (14") | £750–£1,200 | ~70% of rigid |
| Electric (with LED) | 350mm (14") | £1,200–£1,800 | Daylight + nighttime LED |
| Comparison: standard roof light | 550 x 980mm | £2,500–£5,000 | Daylight + opening, view |
What's included in a fitted price
- The dome, reflective tube (rigid or flexible), ceiling diffuser and flashing kit
- Roofer's labour (typically 4–6 hours one-man job)
- Internal plasterboard cutout and skim of the ceiling diffuser ring
- Make-good of the loft insulation around the tube
- 10-year workmanship guarantee from a FENSA/CERTASS-registered installer
Four factors that move the price
1. Run length and number of bends
A straight 1.0m run (typical) is at the bottom of the range. Every metre of tube adds roughly £50; every 30° bend in a flexible-tube install costs about £40 and reduces light output by 5–10%.
2. Roof finish
Standard tile or slate is the baseline. Lead-flashed Welsh slate, single-ply membrane, or fibre-cement slate (Marley Eternit, Cembrit) typically add £100–£250 in flashing-kit cost.
3. Internal ceiling height and run-through
A first-floor bedroom with the unit directly under the loft is the easy case. A ground-floor hallway under a bedroom (i.e. the tube has to box through the bedroom floor void) is a different job altogether — typically £300–£600 extra for boxing and decoration.
4. Brand and dome quality
Velux SUN sells at a 25–35% premium over Lightway or Solatube equivalents. The premium buys you flood-rated flashing kits, a 10-year manufacturer warranty, and parts availability for the next 20 years.
When is a roof light better value than a sun tunnel?
A roof light wins when (a) the room needs ventilation as well as light, (b) you want a view out, or (c) you are planning a loft conversion within five years anyway (in which case a flush-fit Velux is on your future drawings and a sun tunnel becomes a sunk cost). A sun tunnel wins for windowless bathrooms, en-suites, downstairs WCs, internal corridors and walk-in wardrobes where ventilation isn't the bottleneck and openings are not desirable.
FAQs
Related guides
- How much does a roof lantern cost?
- Do I need planning permission for a roof light?
- How much does a flat roof cost in 2026?
- How much does a new roof cost per m²?
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