Component 02 of 10 · Structure

Door frame

Fire door frame & stop. The anchored surround.

The frame carries the leaf and completes the barrier. The stops form the rebate the leaf closes into. The fixings tie the fire door to the structure. The gap between frame and wall must be fire-stopped.

Key facts

Function: Supports the leaf and forms the rebate it seals against
Specification: Stop either rebated from the solid or planted on, to the depth the evidence covers
Materials: Timber to the species and density the evidence specifies, or steel on a steel fire door
Critical tolerances: Per the manufacturer's evidence. Examples: packers behind every fixing; the frame-to-wall gap packed and fire-stopped
Standards: Supplied under the fire door's evidence; installed to BS 8214 and the manufacturer's installation instructions
Role in fire: Maintains the seal line around the entire perimeter of the opening
Where it sits: Fixed into the structural opening, plumb and square

Compliance

BS 8214 is the code of practice for fire door installation. Fire-stopping means closing the gap between frame and structure with a material proven to resist fire, so the barrier is continuous through the junction. An unfilled gap hidden behind the architrave is one of the most common, and most invisible, points of non-compliance.

Did you know

Lifting one architrave often reveals the truth about a fire door: the gap behind it must be packed and fire-stopped, not left hollow or filled with off-cuts.

On the model

Frame head: Continuous seal line across the top
Door stop: Rebated from the solid, or planted on
Jamb: Carries the leaf; must stay plumb
Wall junction: Frame-to-wall gap must be fire-stopped
Fixing point: Packed and fixed to structure

What inspectors check

Work through the checklist with the door closed, then in motion. Every line here is a recordable outcome for a Fire Door Inspector.

Check the frame is covered by the same evidence as the leaf
Identify the stop: rebated from the solid, or planted on
On a planted stop, check it is tight and properly fixed, not just pinned
Confirm fixings at the centres the manufacturer's installation instructions require
Where an intrusive inspection is authorised, lift an architrave to check the fire-stopping, the packers and the fixing positions
Inspect stops for damage and for the depth the evidence covers
Verify the frame is plumb; a twisted frame breaks the seal line and can stop the door closing on its own

Common defects

Frame-to-wall gap not fire-stopped
Missing or compressible packers at fixings
Stop damaged, loose or shallower than the evidence covers
Planted stop pinned only, or lifting off the lining
Frame split at hinge or striker positions
Frame not covered by the same evidence as the leaf
Excessive gap between frame and structure

Go deeper

Door stops: rebated or planted

The stop is the upstand the leaf closes against. It holds the leaf on the seal line and takes the push of hot gases. On a timber frame there are two ways to make one, and they differ in how they are fixed and in what the evidence has to cover.

Rebated from the solid: The stop is machined out of one piece of timber, so stop and jamb are the same section. Nothing to work loose, and nothing to knock off.
Planted stop: A separate strip fixed onto the face of the lining, either pinned or pinned and glued. It can be set on site to suit the leaf. Common on lining sets rather than one-piece frames.Only as good as its fixing. A planted stop held by a few short pins can be pushed off the lining by a leaf under pressure, and the seal line goes with it. Check it is solid, and check the evidence covers a planted stop at all.
Depth: There is no universal figure. Depth follows the lining thickness the manufacturer holds evidence for, so a stop that is correct on one fire door is too shallow on another. Read the evidence rather than a rule of thumb.
What goes wrong: Stops removed to cure a binding leaf, stops split at the striker, planted stops loose along their length, and stops replaced with whatever timber was on the van.

Fixing the frame and closing the gap

A frame that is not properly tied to the structure, and a perimeter gap that is not fire-stopped, are the two things that undo an otherwise correct installation. Both are hidden by the architrave within minutes of being got wrong.

Fixing centres: Commonly a maximum of 600 mm apart, with fixings near the top and bottom of each jamb. The manufacturer's installation instructions set the actual spacing.
Penetration: Fixings are normally expected to reach well into the structure behind, to the depth the installation instructions state. A screw that only bites the plasterboard is holding nothing once the board goes.
Packers: Solid packers behind every fixing point. Without them, tightening the screw pulls the jamb out of line and twists the frame, so the leaf stops meeting the seal line evenly, may no longer close on its own, and the mitre at the head can open into a smoke leakage route. Packers should be non-combustible or as the evidence allows, never compressible foam.
The perimeter gap: The void between frame and structure is filled with the fire-stopping the fire door manufacturer's evidence and specific guidance call for, commonly mineral fibre, with narrow gaps often closed with intumescent mastic or paste. Expanding foam on its own is not fire-stopping.
Architraves: Architrave is a cover mould. Timber architrave offers minimal fire resistance of its own, and it is not fire-stopping. If the only thing over the gap is architrave, the gap is not fire-stopped.This is the most common thing a visual inspection cannot see. Where an intrusive inspection is authorised and appropriately scoped, lifting the architrave shows whether the gap was actually fire-stopped correctly, and where the packers and fixings are.

Fire Door Anatomy is an introduction to fire doors, not the whole subject. Always defer to the fire door’s certification, its test evidence and a competent inspection.