Hygrothermal and fire rated door sets

Hygrothermal risk is a complex area with various forms of modeling available from geographic/barometric conditions to the balance between internal zonal heat flows, the internal wind loading affected by windows, doors, ventilation, corridors and staircases and the variances in humidity arising, throughout the building. The individual building elements need to be able to reasonably cope with the shifting demands of the conditions arising.

There are effectively two dynamics at play. The integrity and behaviour of the external envelope and the extent to which it contributes to the indoor environment, its moisture levels and loads (for vapor diffusion) and the indoor ambient temperature/s (for heat transfer). This is variable over the life-time of the building, influenced by seasonal climatics, access and energy variables and functional changes in the use of the building spaces themselves and as a whole. This applies DIFFERENTIAL temperature & humidity, to either face, which the doorset must resist .

Internal doorsets are incorporated throughout a building in fire separation and escape routes, privacy, detention, congregation, lobbies and general access, egress and circulation areas. The walls and partitions, stairways and corridors, in which they are cited are subject to the above and key applications can be classified to ensure the doorset is able to cope with these demands. The hygrothermal performance of products, like internal doorsets refers to how well these products manage moisture and heat within the building envelope. This includes considerations such as insulation effectiveness, resistance to condensation, and thermal efficiency. Ultimately, they must continue to be ‘fit for purpose’ and continue to fulfil their function, from duty to fire resistance/smoke control, sound attenuation, safety and access, as required of App Docs B, E M & N.

Hygrothermal testing simulates real-world conditions by exposing doorsets to repeated humidity and temperature cycles over the course of 28 to 56 days. This ensures that the doors we produce meet the performance classifications suitable for educational environments, for example, preventing common issues such as swelling, sticking, or distortion, which would otherwise adversely impact fire safety and the very function and performance of the door.

For internal doors there are three classifications: Normal, Humid and Wet:

• Normal
  • No hygrothermal requirements
• Humid
  • One side: 25% Relative Humidity (RH) at 10°C
  • Opposite side: 85% RH at 25°C
• Wet
  • Designed for full wet rooms
  • Beyond the performance scope of a timber doorset

The requirements are as classified in EN12219 where ‘Humid’ is the equivalent to class 3.
The main criteria to achieve this classification is that test specimens cannot deviate to cross curvature of more than 1mm during the course of the test regime. We have tested our stiled and railed door construction to EN1121 and have achieved class 3 meeting the onerous standard demanded by technical annex 2D issued by the Dept of Education.
Any curvature in excess of the above, will impair the performance of the door. CCN now provide the architect and contractor with the means to manage this risk.

Note Hygrothermal performance is not restricted to education buildings and the differential relative humidity/temperature regime of the ‘humid’ conditions above, will serve most applications encountered in any building.

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