How to Replace a Fire Door Leaf Without Replacing the Frame
- FDH Team
- Jul 20
- 3 min read
Practical Guide #9
For: Joiners, maintenance teams, building managers, and anyone tasked with remedial work on certified fire doors.
Why This Guide Matters
Replacing just the leaf is common in retrofit and remedial jobs — especially in housing stock, schools, and commercial buildings. But it's not as simple as swapping out a slab. If you fit a new fire door leaf into an old or unknown frame without confirming compatibility, the whole setup becomes non-compliant.
This guide explains how to correctly and compliantly replace just the door leaf, while retaining the original frame.
1. Confirm You Can Keep the Frame
Start with a thorough assessment of the frame:
Is it in good condition? No warping, splits, movement, or signs of damage.
Is it a hardwood or fire-rated softwood frame?
Does it have a label or mark? Check for a plug, stamp, or branded plate.
Is the wall-to-frame gap properly fire-stopped? (no exposed foam or voids)
⚠️ If you can't verify the frame is certified, or it’s clearly damaged — full replacement is usually required.
2. Identify the Existing Door Rating and Setup
Before ordering a replacement leaf, confirm:
The FD rating required (FD30 or FD60)
Whether the door is smoke-rated (FD30S, FD60S)
If there’s a vision panel — note its size and position
Whether seals are fitted to the frame or the leaf
Where possible, find the original door-set manufacturer. If not available, match to a certified, universally accepted blank (e.g. Halspan, FlameBreak, Pacific, etc.) — but make sure your chosen door is approved for retrofit into existing frames.
3. Measure Accurately (No Guesswork)
See Practical Guide #4 for full measuring guidance.
To summarise:
Measure the existing leaf if still present
If not, measure the frame’s clear opening width, height, and rebate depth
Check hinge positions, lock/latch height, and any closer fixings
Take note of handing (left/right) and leaf thickness
The new door must be sized within the allowed trimming tolerances (usually ≤3mm per edge unless otherwise stated).
4. Prepare the Frame
Before hanging the new leaf:
Clean the rebate and remove any loose paint, sealant, or adhesive
Check the frame is square — measure diagonals
Check and replace intumescent seals if damaged or painted over
Re-firestop any exposed gaps between frame and wall
Repair any minor damage to the frame using fire-rated filler or insert material
If the seals are in the frame and intact, ensure the new leaf will interface properly — especially around hinges and latch zones.
5. Fit the New Fire Door Leaf
Trim only within the manufacturer’s allowable tolerances
Rout and fit ironmongery to exact positions (match existing frame hinge and latch locations)
Use intumescent pads or kits where required (hinges, latch, closer)
Use correct fixings — typically 4.5mm x 32mm steel screws for hinges
Maintain 2–4mm gap at head and jambs
Undercut to no more than:
8mm for FD30 (unless drop seal required)
3mm if the door is FD30S or FD60S
Once hung:
Test the closer
Confirm full, consistent closing action
Confirm latch engagement without slamming
Recheck all gaps with a gauge
6. Label the Replacement (If Applicable)
If the new leaf is certified under a scheme like BM TRADA or Certifire, a label or plug will be visible on the top or hinge edge. Document it. Some retrofit kits include a retrospective door ID label — complete and affix this per instructions.
7. Document the Job
Take before and after photos
Record the new leaf’s make, size, fire rating, and serial number
Note the installer’s name, date, and any changes made to frame or hardware
Add to the building’s fire door log or O&M file
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