The introduction by the European Committee for Standardisation, (CEN) of a series of standards covering the placing on the European market of ducts for fire and smoke management, has set the bar for product safety. Compliance with the standards ensures they are fit for purpose, and perform as intended when called into action.

How do we ensure that it’s not just lip service? How do we ensure the theory meets reality? Can you be certain you have a properly certified product and installation for your client and end user?’

The EN Groupings​

Fire Resistant Ducts

Product Standard

prEN 15871
Fire-resisting ducts.

Classification Standard

EN 13501-3
Fire classification of construction products and building elements – part 3: classification using data from fire resistance tests on components of normal building service installations.

Test Standard

EN 1366-1
Fire resistance tests for service installations: Ducts.

Smoke Control Ducts

Product Standard

EN 12101-7
Smoke and heat control duct systems.

Classification Standard

EN 13501-4
Fire classification of construction products and building elements – part 4: classification using data from fire resistance tests on components of smoke control systems.

Test Standard

EN 1366-8
Fire resistance tests for service installations: Smoke extraction ducts (multi-compartment).

Test Standard

EN 1366-9
Fire resistance tests for service installations: Single compartment smoke extraction ducts.
Simply creating a process does not always ensure perfect outcomes. Beyond reports, there must be a system of checks, and checks on the checks. The concerns to take into account are

Independence of the tests

A manufacturer when developing a product for market, where standards exist, is required to submit the product for testing. This cannot be conducted in-house, and must be completed by an independent laboratory. Reports only by an EOTA (European Organisation for Technical Assessments) approved institution are acceptable. Choosing the wrong test centre will invalidate any claims. Part of the process involves the product being sampled before it leaves the factory, validating the production process and source of the materials.

The construction of the test sample in the laboratory is supervised and documented. The laboratory conduct their own preparations, in line with the chosen test standard. The test is conducted at the relevant air flows and temperatures, with stresses measured in accordance with the test standard.

During the test, observations are documented and recorder with an official report being released a number of months following the completed test. The Laboratory staff will systematically record the performance of the product both electronically and visually so a future classification is possible.

Very often a product will require a series of tests, notably for orientation (Horizontal and Vertical) as well as fire types A and B (fire outside and inside). Lindab Thor Duct has been tested by a number of EOTA approved test centres in Europe, and tested successfully in all orientations, all fire types A & B, and in small square 1250 X 1000, round 1000 Ø and XL up to 2500 X 1250.

Carrying out independent tests in laboratory

Recognising test-based results from assessments

The fire test reports are the basis for issuing a product classification report. Results are reviewed and combined to provide a classification. The classification provides the specifier and end user with a method of determining the product suitability for the considered application. The method of classification is prescribed in the standard and is uniform across all manufacturers. This ensures results are comparable. Having a basic understanding of how to read a classification is important. References to H and V deal with orientation and fire directions I -> o and o <- I detail fire types. Timings are given in minutes and leakage is referenced by S. It is important to note, that the classification standards EN 13501-3 and EN 13501-4 does not provide certification or type approval. This is done under the CE marking process. The classification standard EN 13501-3 specifically requires this to be stated in the classification report (see Clause A.2 (h) or EN 13501-3)

An example is as follows

An assessment, is an appraisal conducted on one type of evidence, for circumstances that were not tested. This is conducted by qualified personnel, with knowledge and experience in fire. They are sometimes referred to as desk top studies. Clearly test evidence is stronger than assessments, however conducting tests are not always commercially feasible or possible due to lack of facilities to replicate unique scenarios. Based on the judgement of the party issuing the assessment, construction requirements and limitations may be issued to meet a potential fire hazard.

The involvement of qualified people in approvals is vitally important. A manufacturer who has a lot of experience in testing and manufacturing will be able to share that experience, however the assessments should be independent.

Lindab Thor Duct ® offers both an EI60 system, and EI90 system, and an EI 120 system, to meet each commercial need.

Production Control

Harmonised European Standards have a section in the product standard called ZA. In one of the ZA sections, you will find the details for affixing of the CE label. The CE marking symbol to affix shall be in accordance with Directive 93/68/EC and shall be shown on a label, and commercial documents. Table ZA.3 will give clarity on the evaluation of this conformity.

The manufacturer is to maintain Factory production control (FPC); and to maintain records of samples according to the standards prescribed testing plan.

The notified body involved, will have continuous surveillance assessment and approval of FPC.

This level of surveillance is important to ensure that product is produced and delivered to the market in keeping with the production standards for the tested samples. It serves manufacturers well to have this level of surveillance, reflecting positively on their desire to maintain the integrity of their product offering. Manufactures will have a document called a “Certificate of constancy of performance”, issued by the notified body, under Regulation 305/2011/EU.

Lindab Thor Duct ® EN is manufactured from FPC facilities.


The best smoke duct in the world, installed incorrectly, will fail. Improving the understanding of both the installer and those tasked with overseeing an installation is critical so as tested is replicated on site. Lindab Thor Duct ® conduct training courses for their installers, with the aim of improving their basic understanding of how ducts perform in fire scenarios, and pointing to the key considerations for an install that mitigates those risks. A focus on brackets, locations, penetration seals are all very important. Training manuals are provided along with evidence of having attended training courses.

Specifiers and M&E Contractors can benefit from an approved CPD program, that goes into more detail about the legal and standards infrastructure around smoke extract ducts and kitchen extract ducts.

Lindab Thor Duct ® are happy to support you with a training opportunity. Contact us to find out more about training and CPD.

Installation and Certification

The ability to demonstrate competency when installing fire systems is strongly supported by the ASFP (Association of Specialist Fire Protection), and we at Lindab Thor Duct encourage our installers to join 3rd Party certification schemes, such as FIRAS. Through their membership, installers can provide those charged with handing over a safe compliant building, the certification to validate that the installation is in accordance with the manufacturers guidelines. These schemes conduct audits on the installers record keeping routines, as well as on site installations. Training records of staff are validated with questionnaires about passive fire, and sites are inspected at a minimum quarterly, ensuring best practice is being maintained. A detailed specification requiring 3rd party certified installers is a useful controlling influence.

Demonstrating that every standard was upheld, every product manufactured and installed professionally, will significantly improve the safety of our buildings.

Then we can say standards and controls prove for best possible outcomes.