Flush doors: wall integration, wood and glazed

For the architect and the construction project manager: a flush door is a preliminary design decision, not a tender-stage trade-off. Specified late, it requires the removal of existing partitions, which cancels out the savings of a light renovation project. Flush integration relies on an aluminium or steel frame embedded in the partition, with no visible architrave. The profile includes a plaster bead that receives the finishing render, allowing a wall-frame junction with a tolerance of 0.5 to 1 mm (aluminium frame supplier specification, verified on our sites). Kytom specifies a partition with a minimum thickness of 98 to 120 mm to accommodate the frame, i.e. 30% more than a standard 72 mm partition.

Normative references governing installation:

• DTU: installation tolerances for interior joinery.
• NF P25-301: requirements for landing door sets.
• NF EN 14351-1: CE marking required on facade or external wall doors.

  Common dimensions observed on our sites:

• Standard height: 2.10 m, executive height: 3.00 m (significant additional cost to budget for).
• Clear passage width: 0.90 m (1 passage unit) to 1.40 m (2 passage units).
• Leaf thickness: 40 mm (standard), 50 to 60 mm (EI 30).

  The Kytom position, contrary to common practice in architecture firms: we advise against flush doors below 6 doors per operation. Industry doxa treats the flush solution as an isolable detail, applicable to a single signature door. Our reading differs: site coordination requires 4 successive phases (partition, frame, continuous painting, leaf) involving 4 distinct trades. Below the threshold of 6 doors, the additional coordination cost is not recouped and the cost/visual-effect ratio becomes unfavourable. On passages of > 300 people/day (lobbies, canteens), we recommend a traditional door set with a metal architrave: impacts quickly degrade the plaster bead in intensive use.

Solid-core wood or glazed: Rw 32 to 38 dB and a noticeable gain in light

The solid-core wood flush door set remains the reference for executive offices and confidential rooms, with a weight of 35 to 55 kg/m² and a sound reduction Rw of 32 to 38 dB depending on the composition (supplier laboratory test report). The acoustic thresholds adopted on our operations are Rw >= 32 dB for standard confidentiality between closed offices, and Rw >= 38 dB for executive offices. For absolute confidentiality (HR, legal, medical), a specific door with an automatic perimeter seal and a drop-down threshold reaches 45 dB (supplier test report, configuration tested on one of our sites).

Kytom mainly works with fine veneered species, natural or stained oak, American walnut, ash stained grey, black or white, selected according to the project and client preferences.

Veneer thickness: 0.6 to 2.5 mm. In our recent production, the flush doors delivered are predominantly wood, the glazed version representing a complementary share depending on the projects.

The glazed version incorporates laminated glass of 8 to 10 mm with partial screen printing, in a minimalist aluminium frame of 25 to 40 mm. The contribution of natural light increases noticeably in circulation areas, helping to reach the target levels of 200 lux in circulation and 500 lux at workstations adopted on our office floors.

For the architect: an acoustic vs light trade-off to be integrated at the concept stage. The glazed flush door is not justified on confidential executive offices: 10 mm laminated glass tops out at Rw 30 dB, below the 32 dB threshold required for standard confidentiality. It is also counterproductive on full south-facing facades without an interior blind: overheating and glare degrade thermal comfort above 26°C in mid-season. On operations where natural light exceeds 800 lux in circulation (ground-floor open spaces on the south side), the additional contribution of the glazed door becomes marginal and the 600 to 1000 EUR excl. VAT extra cost per door is no longer relevant.