Building Regulations Part K and roof lights

Approved Document K (Protection from falling, collision and impact) is one of the technical guidance documents supporting the Building Regulations in England. It addresses guarding, stairs, ramps, doors, windows and glazing — including situations where people could fall, walk into glazing or be injured by broken glass. Roof lights introduce a specific set of considerations because glazing is installed overhead, often above occupied rooms, and may be located on roofs that are accessed for maintenance.

This article summarises how Part K principles interact with roof light specification. It is general guidance only and does not constitute legal advice; your designer and building control body will confirm requirements for your project.

Overhead glazing and impact safety

Part K requires that glazing in critical locations resists human impact and breaks safely. For overhead glazing — including roof lights, roof lanterns and glazed roof panels — the inner pane must retain glass if broken so fragments do not fall into the space below. In practice this means laminated safety glass for the inner leaf, combined with an outer pane sized for wind and snow loads (often toughened).

The detailed rules for glazing classification sit in BS 6262 (Code of practice for glazing for buildings), which Approved Document K references. Impact performance is classified under BS EN 12600. Your roof light supplier should declare the safety glass make-up and provide evidence of compliance with the relevant product standards.

Height, location and risk assessment

The height of the roof light above floor level influences the risk category. Glazing close to floor level in doors and full-height panels has strict impact class requirements; overhead units at ceiling level still require safety glass but the critical failure mode is falling glass, not walk-into impact. A project-specific risk assessment may impose additional requirements — for example, in schools, sports halls or areas where balls or objects could strike the outer pane from above.

Guarding and accessible roofs

Part K also covers guarding where there is a fall risk. A roof light flush with a flat roof deck does not usually require its own guard rail, but if the roof is routinely accessed — for plant maintenance, solar panel cleaning or as a terrace — guarding at the roof perimeter and around other hazards may be necessary. Work at height regulations and HSE guidance on fragile roofs complement Part K: installers and maintenance teams must use appropriate access equipment and may need temporary protection over unglazed openings during construction.

Stairs, ladders and roof access

Where a roof light is installed in a loft conversion or stairwell, Part K provisions on headroom, stair dimensions and guarding at landings apply to the wider design. The roof light itself must not create a collision hazard at head height on a stair flight. Upstand kerbs and frame profiles should be coordinated with the architect so finished floor-to-glazing dimensions meet the guidance.

Relationship with other Approved Documents

Part K does not operate in isolation:

• Part B — fire safety and fire-resisting construction may affect glazing in separating elements.
• Part L — thermal performance of the roof light unit.
• Part F — ventilation if the roof light is openable.
• Part O — overheating risk from large roof glazing areas.

Product selection should satisfy all applicable parts simultaneously. A roof light that meets thermal targets but lacks the required safety glass build-up would not comply overall.

Practical specification checklist

When reviewing roof light compliance against Part K principles:

1. Confirm safety glass classification for inner and outer panes with your supplier.
2. Verify fixing and retention — the frame and beads must hold the unit if glass is damaged.
3. Assess access and maintenance routes to the roof and any guarding needs.
4. Coordinate with the structural engineer for imposed loads if the roof is walk-on or supports maintenance traffic.
5. Retain declarations of performance and test evidence for building control.

Made-to-measure roof lights can be configured with the correct safety glass build-up for your opening size and regulatory context — see custom roof lights for size and specification options.

Vant Glass manufactures premium roof lights and glazing in Aintree, Liverpool — made in Britain, 20-year guarantee, free UK mainland delivery. Explore all products or call 03330 902 592.