Fire Door Specification Calculator — FD30/FD60 Rating per Part B

In a standard 2-storey dwellinghouse (top floor up to 4.5m above ground), fire doors to habitable rooms are generally NOT required under Approved Document B Volume 1 — instead each habitable room (except the kitchen) must have an escape window or external door, or direct access to the protected stairway. Once a floor sits more than 4.5m above ground (3 or more storeys, including a loft conversion that adds a 3rd storey) the stairway must be enclosed and the doorsets onto it need a minimum of E 20 (FD20), not FD30. AD B Vol 1 para 2.21b calls for fire resisting doors (minimum E 20) and partitions (minimum REI 30), and Table C1 item 11(b) rates a doorset forming part of the enclosures to a protected stairway in a single family dwellinghouse at E 20 / FD 20 with no Sa suffix, so no smoke seal is required; Appendix C5c also excepts fire doorsets within a dwellinghouse from the self-closing rule, so no door closer is needed either. FD20 doorsets are no longer manufactured or third-party certified, so an FD30 door is what you buy to satisfy the E 20 minimum, which exceeds the requirement rather than being the requirement. In HMOs all habitable-room doors to common areas must be FD30S, and in flats the E 30 Sa entry at Table C1 item 4a applies. The one fire door needed in a typical 2-storey house is the integral garage door, which must be FD30S with smoke seals and a self-closer (Table C1 item 11a).

FD30 provides 30 minutes of fire resistance (integrity). FD30S adds an "S" for smoke seal, meaning the door includes cold smoke seals that prevent smoke passage at ambient temperatures. Flat entrance doors and HMO room doors require the "S" designation with combined intumescent and smoke seals, and so do doors to a protected stairway in every building type except a single family dwellinghouse: Table C1 item 4a rates "a protected stairway (except as described in item 9 or 11(b) below)" at E 30 Sa, while item 11(b) puts the house stairway doorset at plain E 20 / FD 20 with no Sa suffix. Inside a house the one door that does need the S suffix is the door between the dwelling and an integral garage (item 11a, E 30 Sa). The smoke seal is typically a nylon brush or blade type fitted within the intumescent strip.

All fire door ironmongery must be CE-marked and fire-tested as part of a door assembly. Requirements include: 3 ball-bearing hinges to BS EN 1935 (grade 12, 13 or 14 acceptable where a self-closer is fitted — grade 13 is the common spec), a self-closing device (BS EN 1154, though AD B Vol 1 Appendix C5c excepts fire doorsets within flats and dwellinghouses, so an internal house door takes no closer while the door to an integral garage still does), intumescent strips in the frame or door edge, a fire-rated lock or latch (BS EN 12209), and signage (Fire Door Keep Shut to BS EN ISO 7010 / BS 5499-4). Letterplates are generally not permitted unless fire-rated to BS EN 13724. All items must be fitted per the door manufacturer's installation instructions.

Yes, all fire doors require intumescent strips to seal the gap between door and frame during a fire. The intumescent material expands when heated to approximately 200 degrees C, sealing gaps and preventing fire and smoke passage. Standard sizes are 10mm x 4mm for FD30 doors and 15mm x 4mm for FD60 doors. They are fitted into a groove in either the door edge or the frame rebate. Some locations also require a combined intumescent and cold smoke seal.

Yes, but the glazing must be fire-rated to match the door rating. For FD30 doors, Georgian wired glass (6mm) or proprietary fire-rated glass such as Pyran S or Pyroguard can be used. The maximum glazed area is typically 0.5 square metres unless the manufacturer has test evidence for larger panes. The glazing beads must incorporate intumescent backing strips. All glazed fire doors must be tested as complete assemblies to BS 476-22 or BS EN 1634-1.