Domakihub How to Fit a Fire Door: A Complete Installation Guide
Everything you need to know to fit an FD30 fire door correctly — from frame prep to intumescent seals and door closers.
Reviewed by Domakihub home & decor pros · 2026-06-23 · 6 min read
Fitting a fire door is one of those jobs that looks like straightforward carpentry but carries serious safety and legal weight — get it wrong and the door that is supposed to buy you 30 minutes of escape time may fail in five. The video above shows a real installation in detail; the steps below break the process into a clear sequence that homeowners, holiday-rental operators, and hotel managers in Greece can follow or use to supervise a contractor. Greek building regulations (Κανονισμός Πυροπροστασίας) require fire doors in specific positions such as stairwells, plant rooms, and multi-unit dwellings, so understanding the process helps you brief trades, check the finished result, and avoid costly remediation.
What Is a Fire Door and Why Does the Detail Matter?
A fire door is a tested assembly — not just a thick slab of timber. The door leaf, frame, hinges, intumescent seals, smoke seals, and self-closing device are all certified together. Remove or substitute any one component and the certified fire resistance (commonly FD30, meaning 30 minutes' resistance, or FD60 for 60 minutes) is voided. In Greece, fire doors are typically required in communal stairwells of apartment buildings, between garages and living spaces, in hotels exceeding a certain floor area, and wherever a fire-safety plan specifies a rated barrier.
The key difference from a standard internal door is the gap tolerance. A fire door must be hung with a consistent 3 mm gap on the three sides (top and both sides) and no more than 8 mm at the bottom (or less if a smoke seal is required). These tolerances are not guidelines — they are part of the certification. A gap that is too large lets fire gases through; a gap that is too tight prevents the intumescent strip from compressing correctly and can stop the door closing.
When to Use a Qualified Installer — and When Regulations Demand It
In the UK (where most FD30 certification standards used across Europe originate), the British Woodworking Federation and the Fire Door Inspection Scheme strongly recommend that fire doors are installed by a trained and certificated installer. Greek fire-safety consultants (Μελετητές Πυροπροστασίας) take a similar position: in buildings requiring a full fire-safety study (μελέτη πυροπροστασίας), the installation may need to be signed off by a certified professional. For HMOs, hotels, and holiday rentals subject to licensing, an independent fire-risk assessment will check the quality of the installation.
That said, a competent DIYer or general carpenter can fit an FD30 door in a private single-family home legally and safely — provided they source a complete certified door set, use every supplied or specified component, and do not deviate from the manufacturer's installation instructions. The steps below describe exactly that process.
How to Fit a Fire Door: 5 Steps
- 1
Prepare and check the door frame
Before lifting the door leaf, assess the existing or new frame. The frame must be structurally sound, plumb, and square — check all four corners with a framing square and verify the reveal is consistent. If you are installing a new lining, fix it into the rough opening with the correct fixings for your wall type (timber studs, blockwork, or concrete), packing as required. For a fire door, the frame itself should be either part of the certified door set or a tested compatible lining; do not reuse a lightweight softwood lining that came with a standard door. Once the frame is in place, measure the opening height and width at three points each to confirm there are no significant bows or tapers that would prevent an even 3 mm gap.
- 2
Size and prepare the door leaf
Fire door leaves must never be cut more than the manufacturer permits — typically a maximum of 6 mm from the top or sides and around 10–20 mm from the bottom. Exceeding these limits removes the fire-rated core material and voids the certification; check the data sheet supplied with your specific door. Plane or trim the edges to achieve your target 3 mm gap on the latch side, hinge side, and top. Use a straight edge to ensure the planed faces are flat and square. If the frame is slightly out of plumb, it is always better to adjust the frame than to over-trim the door. Sand all cut edges lightly and, importantly, seal them immediately with a fire-rated end-grain sealant; unsealed exposed core can absorb moisture and swell, altering the gap.
- 3
Fit the intumescent strips and smoke seals
Intumescent strips are the narrow bands of expandable material that swell when heated, filling the 3 mm gap and preventing fire from tracking around the door. They can be supplied pre-fitted into the frame rebate or as loose strips to be let into a routed groove. If routing, cut the groove in the frame stop or door edge to the depth and width specified by the strip manufacturer, then press the strip into the groove without adhesive unless the manufacturer states otherwise — adhesive can interfere with expansion. Many modern fire door sets also require a brush-type smoke seal, fitted above or alongside the intumescent strip, to block cold smoke passage. The smoke seal is usually friction-fit into the same groove or a separate groove. Fit strips on the latch side, hinge side, and top — never the bottom, which is handled by the threshold gap or a drop-down smoke seal if specified.
- 4
Hang the door with fire-rated hinges
Fire doors require a minimum of three hinges (for doors up to 2100 mm height) and the hinges must be CE-marked or equivalent and listed in the door set's certification. Typically these are 100 mm solid brass or stainless steel butt hinges or CE-rated steel ball-bearing hinges. Mark hinge positions on the door edge — conventionally at 150 mm from the top, 225 mm from the bottom, and one centred between them. Cut the hinge recesses (housings) with a sharp chisel to the exact hinge-leaf thickness so the hinge sits flush; a hinge proud of the surface creates a gap on the opposite side. If intumescent hinge pads are required by the certification (check the door set documentation), fit these under each hinge leaf before screwing off. Hang the door on the frame using all screw holes with the correct length and gauge of screw — do not use shorter screws than specified. Check the gap is even and the door swings freely without rubbing.
- 5
Fit the self-closing device and check the complete assembly
Every fire door must be fitted with a CE-marked overhead door closer that is strong enough to return the door fully to the closed and latched position against any draught or carpet resistance. Fit the closer to the manufacturer's template, adjusting closing speed and latching action. The door must click fully into the latch; if it rebounds or does not latch, increase the latching speed on the closer's adjustment valve. Once closed, run a final gap check on all four sides — use a 3 mm drill bit as a feeler gauge. Check that the intumescent strips are undamaged, that no hinge screws are missing, and that the door is not sticking or binding. Finally, attach the door's certification label (required for third-party inspections) to the top of the door edge or in the frame rebate as specified, and retain all documentation — test certificates, CE declarations, and the installation instructions — in the building's fire safety file.
Rather have a pro handle it?
Get a vetted renovation pro in your city — one number, booked in EN/EL/DE.
FAQ
- Can I fit a fire door myself or do I need a certified carpenter?
- In a private single-family home you can fit an FD30 fire door yourself provided you follow the manufacturer's installation instructions exactly, use all specified components (hinges, intumescent strips, closer), and keep all certification paperwork. For hotels, multi-unit apartment buildings, and licensed holiday rentals in Greece, a fire-risk assessor or the fire-safety consultant who signed off the building's μελέτη πυροπροστασίας may require a qualified installer and signed-off inspection record — check with your local fire authority before starting.
- What happens if the gap around my fire door is larger than 3 mm?
- A gap over 3 mm means the intumescent strip will not fully seal the opening when it expands in a fire. Hot gases and flames can bypass the door far sooner than the rated 30 or 60 minutes. Remedies depend on where the oversize gap is: if the frame is sound you may be able to add a wider intumescent strip profile, fit an additional door stop, or in some cases adjust the hinge recesses to shift the door leaf. If the frame itself is out of square or has moved, the frame must be reset before any other fix will hold.
- Do I need a building permit to replace an existing fire door in Greece?
- Simply replacing a like-for-like fire door (same size, same position, same certification rating) in an existing residence generally does not require a new building permit (οικοδομική άδεια) in Greece. However, if the project involves changing the door opening size, relocating the door, or is part of a larger renovation that already requires a permit, the fire door work falls within that permit's scope. For commercial properties, hotels, and HMOs that hold a fire-safety certificate (πιστοποιητικό πυρασφάλειας), any change to fire compartmentation — including doors — should be reported to your fire-safety consultant so the certificate remains valid.