Incorrectly Sized and Inadequately Fixed Fire Doorset
The fire doorset appeared to be undersized for the structural opening, resulting in an excessive gap between the frame and the supporting wall. The gap had been built out using multiple layers of plasterboard and intumescent sealant rather than an approved, tested packing and fire-stopping detail. This raised serious concerns about whether the frame fixings were long enough to pass through the packing and achieve the required embedment into the structural substrate. An inadequately supported or fixed frame may move, distort or detach during use or fire exposure, compromising the doorset’s fire-resistance and smoke-control performance. The complete installation should be checked against the doorset manufacturer’s instructions, fire-test evidence and approved opening detail.
- NCQLE reference
- NCQLE-2026-00016
- Quality topic
- Installation quality
- Lesson type
- Failure
- Evidence rating
- Experience
- Published
- 1 August 2026
- Last reviewed
- 3 August 2026
Evidence basis: Supported by relevant professional experience. This learning is provided for professional consideration and does not replace project-specific competent advice, statutory duties or contractual requirements.
Context
The issue was identified during an inspection of a fire doorset installed within an internal compartment wall, within a Hospital. The door frame appeared undersized for the prepared structural opening, and the excessive perimeter gap had been built out with multiple plasterboard strips and intumescent sealant. The inspection took place while the frame junction remained visible, allowing concerns about packing, fire-stopping, fixing length and embedment into the supporting construction to be raised before the installation was fully concealed. During inspection, the fire doorset appeared to be too small for the structural opening, leaving an excessive perimeter gap around the frame. The gap had been packed with several layers of plasterboard and filled with intumescent sealant. Concerns were raised that the frame fixings might not be long enough to pass through the built-out packing and achieve the required embedment into the structural substrate. The installation did not appear to follow a clearly approved or tested fire-door frame detail.
The transferable lesson
Fire doorsets must be correctly sized for their structural openings and installed within the permitted perimeter tolerances of the tested system. Excessive gaps must not be made up using unapproved layers of plasterboard, foam or improvised packing. Frame fixings must pass through any approved packing and achieve the specified embedment into a suitable structural substrate; otherwise, the stability and fire performance of the entire doorset may be compromised.
Recommended action
Survey and record each structural opening before ordering the fire doorset, ensuring the frame size allows for the manufacturer’s permitted installation gap. Approve a benchmark installation and verify the supporting construction, packers, fixing type, fixing length, spacing and minimum embedment depth. Inspect and photograph the frame fixings and perimeter fire-stopping before architraves conceal them. If the gap exceeds the tested system’s limits, obtain a project-specific approved detail or install a correctly sized doorset, do not rely on improvised plasterboard packing or unapproved foam.
Limitations and application
Permitted frame-to-wall gaps, packing materials, fire-stopping products and fixing requirements vary between doorset systems and supporting wall constructions. A visual inspection cannot confirm fixing length, embedment depth or whether the intumescent sealant and plasterboard form part of an approved tested detail. Compliance must be verified against the manufacturer’s installation instructions, fire-test evidence, field of application and door schedule. Any remedial proposal should be approved by the doorset manufacturer or a competent fire-door specialist.