A contractor gave us dimensions over the phone: ninety by two hundred, net. The doors were made, shipped, and none of them fitted, because his figure was the structural opening and we had read it as the clear frame opening. The difference is the frame section on each side. On a fire door that error costs more than usual, because the frame cannot be cut and extended on site; the rating depends on a tested fixing detail.
Three dimensions, three meanings
- Structural opening: the clear width and height left in the wall. The frame goes into this.
- Clear frame opening: what remains as passage once the frame is installed. Evacuation width calculations use this figure.
- Architrave edge: the overall outside dimension that frame and casing occupy on the wall.
State which one you are quoting. On our standard product the clear frame opening is 90×200 cm while the architrave edge measures 104×208 cm.
When to measure
Measure after the walls are built and before plastering starts. Too early and the plaster allowance is missing; too late and production time falls outside the programme. The working sequence is: wall complete, finished floor level marked, measurement taken, frame installed, plaster brought up to the frame, floor finish laid, architrave fitted last.
Width, height and square
Take width at three heights, roughly 20 cm from the floor, at mid height and at the head, and use the smallest. Take height at both jambs and use the smaller. Measure both diagonals: a difference over 1 cm means the opening is out of square and must be corrected at frame installation. On a fire door this matters because the perimeter gap around the leaf has to stay within the tested range; a wide gap on one edge weakens the rating.
Wall section and frame depth
Wall construction counts twice. First for frame depth, which must grip the wall with plaster and finishes allowed for. Second, and more important, for the tested fixing detail: anchor type, anchor spacing and frame void filling differ between concrete, masonry, aerated block and drywall partitions. So the wall type and total thickness belong in your enquiry alongside the width.
Finished floor level and bottom gap
This is the item most often missed. If the floor finish is not yet laid, height must be calculated to finished floor level. Screed, underlay, tile and adhesive easily add several centimetres, and without that allowance the door either binds on the floor or leaves an unacceptable gap. On a fire door the bottom gap is not a free dimension; it has to stay within the tested range, and whether a threshold is used is decided at this stage too.
Door hand and escape direction
On a fire door the hand is not an aesthetic choice. A door on an escape route opens in the direction of travel. Decide it on the plan: check that the open leaf does not narrow the corridor, does not swing over a stair tread, and does not block passage when held back against the wall. Define the hand as seen from outside the door and attach a simple sketch; that ends most confusion.
What to send us
- Structural opening width and height in centimetres, smallest values
- Diagonal difference
- Wall type and total thickness
- Finished floor level and any remaining floor build-up
- Door hand as seen from outside, with a sketch
- Required resistance class and rating
- Hardware requirements: panic bar, closer, louvre, vision panel, access control
- Single or double leaf, and which leaf is inactive
With that information we can quote to your measurements. Send photographs and a dimensioned sketch of each opening and we will confirm the fire door system to suit. Apartment and common-area doors follow similar logic with easier tolerances; we use a separate measurement form for building entrance doors. Frames and leaves ship crated from Istanbul with installation manuals included.
