Old doors get new life and better smoke density

Is it possible to improve the smoke tightness of old apartment doors? This has been the focal point of a knowledge bridge project where DBI and A4 arkitekter og ingeniører A/S have tested various improvements that can make old doors meet today’s classification requirements.

In stairwell after stairwell in Danish cities, there are old infill doors that have had a long life. If A4 arkitekter og ingeniører A/S has its way, that life can easily be even longer.

 We advise owner-occupied and cooperative housing associations on renovating their residential properties. The doors to the apartments typically come into play when the stairwells are renovated. Until now, we’ve only been able to offer new doors because we haven’t had the knowledge of how and how much to improve the existing doors. And that’s a shame – both in terms of economy, aesthetics and sustainability. Despite their age, the doors can still be in good condition in terms of materials, even if they are functionally in poor condition,” says Kasper Scotte, architect at A4 arkitekter og ingeniører A/S.

This was the reason why the consulting architectural and engineering firm approached DBI to learn more about the fire-technical properties of old doors. This has resulted in a project where DBI and A4 arkitekter og ingeniører A/S have now investigated how to improve the smoke tightness of old doors.

In addition to the safety aspect, the same tightness – or lack of it – determines how energy-efficient and sound-absorbing the doors are – Kasper Scotte, A4 Architects and Engineers

100-year-old door

At DBI, a 100-year-old door was subjected to a series of smoke tests – both cold and hot tests – where the door was repaired step by step, after which DBI measured the effect of the specific repairs. The door was fitted with new sealing strips in the frame, the sealing strips were adjusted to the door’s skew, gaps between frame and wall – which are often hidden by frames – were sealed, and various holes from the previous lock, door viewer and letter slot were closed. Finally, the door has also been fitted with a plywood panel that covers the entire side that is inside the entrance hall.

New sealing strips and sealing between frame and wall had a good effect on smoke tightness and can be described as low-hanging fruit in the improvement of old doors. But the biggest effect was achieved by combining the new sealing strips with the installation of the plate, which makes the door significantly stiffer. Generations of use of the door loosen the panel frames and make the door ‘jointless’ and thus leaky,” explains Trine Dalsgaard Jensen, an engineer in DBI’s fire test department.

Complies with EN13501-2

Several of the improvements combined had such a large effect that the door met the classification requirements for smoke tightness in EN13501-2.

It wasn’t a goal in itself, but we went into the project with the hope that it could be done. It’s more powerful to be able to say to a housing association that their old doors can meet today’s classification requirements for smoke tightness rather than talking about percentage improvements,” says Kasper Scotte.

A4 arkitekter og ingeniører A/S is now working on the results of the project with DBI and sees the combination of new sealing strips, sealing between frame and wall and not least the installation of the plywood panel as an optimal solution.

 In addition to giving the door leaf new rigidity, the panel also covers the old holes in the door. We’re also testing insulating the cavity between the door fillings and the panel with a filling material in the form of Diathonite Thermactive.037 cork plaster from Diasen,” says Kasper Scotte.

It is a fire-resistant insulation material and gives a hint of what the next step could be for A4 arkitekter og ingeniører A/S.

As an alternative to new fire doors in the stairwells, it would be interesting to have a new project that uncovers whether it is possible and what it would require to fireproof old doors to comply with BD30 – Kasper Scotte, A4 Arkitekter og Ingeniører