In your most recent trip to the airport you may have noticed that it’s rather standard for gates to be compartmentalised by glazed doors installed in infinitely long partitions. The same types of systems exist on storefronts at the mall, or the glazed units which separate a parking garage from an escalator bank in a commercial building.
These types of systems are often fire-rated, but how does one go about fire-rating an infinitely expansive system? The usage conditions on these systems, with respect to the supporting construction they’re installed in, is starkly different than, say, a traditional apartment unit door in a high-rise.
The role of a supporting construction
First, let’s consider what a supporting construction is. In broad terms, it’s the wall a door or other passive element is installed in. The wall, typically, has a known fire performance and when a door is installed in it, testing is performed to demonstrate that the continuity of the wall-performance is maintained.
Standard supporting construction
These walls often, but not always, tend to fall into a category of standard supporting constructions – generally either low or high-density rigid supporting constructions, or gypsum-based flexible supporting constructions. EN 1363-1, the General Procedures standard for Resistance to Fire Testing under the European Harmonised Standards, conveniently outlines what makes a supporting construction standard, or even how to make one.
For example, a low-density rigid supporting construction will be aerated concrete blocks with a density of 650 ± 200 kg/m3; a high-density rigid supporting construction will be standard masonry or homogenous concrete with a density of ≥ 850 kg/m3; and a flexible supporting construction will be a stud-framed wall with layer, web-depth and installation characteristics given in EN 1363-1.
Then, EN 1634-1, the European standard for doors, outlines how a door tested in one standard supporting construction may, or may not, apply to installing in a different type of standard supporting constructions.
But, not all supporting constructions are standard, and some are even associated supporting constructions.
Non-standard supporting construction
Strictly speaking, a non-standard supporting construction is anything that doesn’t fit within the requirements laid out in EN 1363-1. It can be confusing because when something is installed and tested in a gypsum wall then that is, indeed, a flexible supporting construction, but it may not be a standard flexible supporting construction. By virtue of not being standard, the EN 1634-1 door standard lends few allowances to the applicability of the test to other supporting construction.
But, if we return to the airport and mall model, with a door installed in an infinitely long partition, what actually is the supporting construction? Is it non-standard, or is it associated?
Associated supporting construction
The airport and mall model is best illustrated with glazed systems because framing components used to make a door and a partition are often part of the same larger system – i.e. one may use the same transom and mullion profiles to make a door frame, or leaf, as they do for the partition, then integrate them. This example, however, is not exclusive to glazed systems; it’s just the clearest example.
The boundaries of what is and what is not an associated supporting construction (ASC) in EN 1634-1 can be difficult to understand. EN 1634-1 itself defines an ASC as a “specific construction in which the doorset or openable window is to be installed in practice and which is used to close off the furnace and provide the levels of restraint and thermal heat transfer to be experienced in normal use.”
In concept, that’s just any supporting construction, standard or non-standard, rigid or flexible. But in the use of the test standard, it’s best to understand it in terms of the airport and mall model – a door installed within a partition system that is from the same system catalogue, which may be integrated with the door, and which may require infinite extension.
But, what is the difference between having side-lights, transom panels, or over panels in a door system vs. viewing the door as installed in an ASC with the same arrangement of adjacent, non-swinging panels to the door leaf or leaves? The bottom-line, key to understanding this is fixity: Is the partition system fixed to and within the test frame, or not?
Routes to compliance
The goal in fire-testing is to gain compliance of a building product with desired variations. In an ideal scenario, the route to compliance would be explicitly stated in a testing standard, but this is not always the case. It must be understood that EN 1363-1 is a general procedures standard which has information for supporting constructions, then EN 1634-1 is the specific product testing standard for doors which gives simple allowances based on test scenarios, then EN 15269 (which has many parts) is an Extended Application (EXAP) standard which outlines more possible variations. None of these standards, in part or together, lend substantial allowances to associated supporting constructions.
For scenarios which lack explicit allowances, it is often the case that a certification body (CB) or other party will make engineering judgments as a route to compliance. Those routes may differ from one CB to another, but an interpretative example can be understood in the following two cases, both of which consider a glazed door with glazed panels above and to either side of the door leaf.
Scenario 1 – Side and Transom Panels: The door, which is integrated with surrounding glazed panels creating, essentially, a partition, is installed within a test frame. All four edges of the system are fixed rigidly within the test frame.
By virtue of having all four edges fixed, this is a door installed with side and transom panels, not an associated supporting construction. The results, essentially, apply to that system and there is not recourse to connect this test evidence with another test in service of extending the partition system indefinitely, which is fine, because that may not be required.
Scenario 2 – Associated Supporting Construction: The same exact overall construction is installed in the same test frame, but this time with the vertical edges of the partition not fixed to the test frame, or otherwise using free edges. There is a possible route to compliance here considering that:
- This test evaluates the integration of the door with the partition, and the partition is indeed a partition because it has unrestrained edges.
- Then, a second test may be conducted on the partition alone under EN 1364-1, which would give the partition system expansion allowances.
- Then, a CB or qualified party may be able to write a justification tying the door and partition tests together to allow someone to install the door in an infinitely long airport concourse, or mall-front.
- And a third, or more, tests could be done in other supporting constructions with the doorset alone to widen the applicability to other constructions.
Scenario 2 is broad example of one route to compliance, but an overall example of understanding how associated supporting constructions can be managed with sufficient pre-test planning.
