Solid-core wooden doors: premium for office spaces
Acoustic performance: Rw from 32 to 42 dB
Rw 32 to 42 dB for 850 to 2,400 euros excl. VAT per door set: the solid-core wooden door is not an aesthetic choice, it is an acoustic trade-off. The difference of 12 to 18 dB versus a hollow-core door (Rw 22 to 26 dB) determines speech-to-speech confidentiality in management offices, law firms and boardrooms. Kytom has specified them regularly on its high-end projects since 2006, particularly in management offices, law firms and boardrooms. The standard 2040 x 830 mm leaf weighs 28 to 45 kg compared with 12 to 18 kg for the hollow-core type, a mass that provides three advantages for the prescribing architect: Rw acoustic insulation compliant with office acoustic requirements, category 4 impact resistance, dimensional stability up to 2400 mm. Installation follows the DTU, with hardware certified EN 1935 grade 13 and EN 12209.
NF S 31-080 sets three insulation targets between office spaces: Rw = 32 dB for a shared office, Rw ≥ 38 dB for a management office, Rw ≥ 45 dB for absolute confidentiality (lawyer, HR, medical). A hollow-core door tops out at Rw 22 to 26 dB, insufficient for speech-to-speech confidentiality.
A solid-core wooden door achieves:
- Rw 32 dB in the standard version, 720 kg/m³ particle board core
- Rw 35 to 38 dB with EPDM acoustic perimeter seals
- Rw 40 to 42 dB with an automatic drop seal and double seal
The difference between solid-core and hollow-core reaches 12 to 18 dB depending on the configuration. On our premium office projects, management offices and confidential meeting rooms are systematically specified with a solid core of Rw ≥ 35 dB. The acoustic premium for a solid-core door set generally ranges between 220 and 380 euros excl. VAT depending on the ranges and finishes.
Our reading differs from the industry’s reflex on this specific point. The prescriber’s conventional wisdom consists of systematically targeting Rw 38 to 42 dB on all closed cells, as a safeguard. In practice, the limiting factor is almost never the door but the partition wall: a single-skin BA13 tops out at Rw 35 dB, a double-skin BA13 with rock wool reaches Rw 47 to 52 dB. Specifying an Rw 42 dB door behind an Rw 35 dB partition means paying an extra 380 euros excl. VAT for an overall insulation pulled down by the weakest link. The Kytom rule: the door is sized to the target partition Rw minus 3 dB, no more.
When an acoustic solid core is not justified. Below a target Rw of 30 dB (open, non-confidential offices, break rooms, secondary circulation areas), the additional cost of 220 to 380 euros excl. VAT per door set does not pay off: a densified or semi-solid hollow-core door is sufficient, with a better cost/acoustic-performance ratio.
Four premium wood species: oak, walnut, ash, HPL
The breakdown of Kytom specifications on premium projects, with all solid wood species PEFC or FSC certified, is consistent with the environmental requirements of the usual office standards and HQE Tertiary Building.
| Species | Typical use | Bare leaf budget excl. VAT |
|---|---|---|
| French sessile oak | Management, reception, boardrooms | 780 to 1,100 € |
| American walnut | Law firms, executive offices | 1,100 to 1,450 € |
| Tinted ash | Closed offices, meeting rooms | 480 to 720 € |
| High-end HPL veneer | Healthcare, food industry, tight budget | 320 to 560 € |
Excluding hardware and installation.
Standard finishes include 3-coat polyurethane varnish, matte or satin RAL-tinted lacquer, and hard oil. Non-air-conditioned premises in Mediterranean or coastal regions require a finish on all 6 faces (leaf plus top, bottom and side edges) to stabilise the wood between 40 and 65% relative humidity. The prescribers of Kytom’s 11 branches in France and Spain select the species according to acoustic zone, fire zoning and humidity exposure recorded during the technical visit.
For the architect: arbitrate material-traffic consistency, not the image. The classic prescriber reflex consists of imposing oak or walnut on all closed cells for aesthetic consistency with the management furniture. On a project with intensive traffic exceeding 300 openings/day per door (call centres, dense open-plan floors, public reception areas), oak or walnut wear prematurely at the edges and the handle area: high-end HPL veneer becomes a rational specification, with an equivalent edge lifespan for a budget divided by 2.5. Likewise, on an overall fit-out budget below 600 euros excl. VAT/m², a solid core in oak or walnut absorbs a disproportionate share of the envelope: redeploying towards HPL or tinted ash frees up budget for the partition or ceiling acoustics, which are more decisive for perceived comfort.
Kytom’s 5-step method over 12 weeks
The specification and installation process follows a sequence proven across all our projects:
- Technical survey (week 1): measuring openings to the millimetre, qualifying the support (BA13 72/48, movable partition, masonry), identifying acoustic and fire-resistance constraints by zone.
- Specification (weeks 2-3): selection of species, finish, hardware (3D ball-bearing hinges EN 1935 grade 13, brushed stainless steel handles, multipoint locks EN 12209).
- Validation by sampling (week 4): any project exceeding 20 doors benefits from a signed physical sample before ordering.
- PEFC or FSC workshop manufacturing (weeks 5-11): lead time of 4 to 7 weeks depending on the species; noble species (American walnut, French sessile oak) can reach 10 to 14 weeks in high season.
- Joinery installation (week 12): trained craftsmen, laser plumb check, perimeter clearance calibrated to 3 mm, closing test on each unit, detailed acceptance report.
Installation fully follows the interior joinery DTU.
When this 12-week method does not apply. On an urgent replacement project of fewer than 10 doors (damage claim, postponed delivery, express fit-out), sequencing at the standard lead time with physical sampling is disproportionate: a process shortened to 5 weeks on a catalogue HPL or stocked ash reference is more rational, with the physical sample becoming optional. Conversely, on projects of more than 80 doors in noble species, allow 16 to 18 weeks (not 12) to absorb workshop contingencies in high season.
EI30 and EI60 fire resistance, full budget and lifespan
A solid-core wooden door can be certified as fire-resistant provided it is a door set tested according to the fire-resistance test standard applicable to door sets and CE marked, with a valid fire classification report. The EI30 (30-minute resistance) and EI60 (60-minute) classifications cover 95% of ERP requirements and of the regulations applicable to office premises (articles R 4216-7 to R 4216-10). The EI30 fire-resistance premium generally ranges between 180 and 280 € excl. VAT per door set, and between 320 and 480 € excl. VAT for an EI60 classification, depending on the project configuration.
Full budget for an installed door set (leaf, frame, hardware compliant with the standards in force for hinges and locks, DTU installation):
- Standard oak or ash, without enhanced acoustics
