How To Write A Perfect Spec

Have you noticed, “What did the spec say” is often the fall back when a problem is identified! A robust specification is vital to ensuring all parties remain focused on delivering a compliant solution, and the specification is the lynch pin for all parties to your project. Getting it right from the start begins with our specification. The ingredients of a good specification are:

For smoke extraction ductwork

the suggested specification can be written as follows:

All Thor Duct® Smoke Extract ductwork will be to standard EN12101-7 and tested to EN1366-8 for multi compartment or EN1366-9 for single compartment.

Where multi compartment ductwork is required it must be insulated to the same period of time as the compartment through which it passes as required in DW172. Insulation to be used must be included in the manufacturers EN 1366-8 test. Alternatives are not acceptable, combinations not accepted.

Evidence of a Factory Production Control (FPC) being in place must be provided.

All Smoke Extract will carry CE Marking or UKCA as appropriate, complying with EU regulation 305. All ductwork must have classification for testing outside (A), inside (B) and smoke extract (C) in both a horizontal and vertical position.

All ductwork rated “S” for smoke leakage and have been tested to high pressure 1500 PA. All smoke extract will be tested in a flexible wall and be suitable for installation in stud partition, block wall and concrete floor.

All Smoke Extract is to be installed under a third-party certifier such as Firas as identified in ASFP TGD 18.

For Kitchen Extract

the suggested specification can be written as follows:

All Thor Duct® Kitchen Extract will be to the standard prEN15871 and tested to EN1366-1. Insulated to the same period of time as the compartment through which it passes as required in DW172:2018 2nd Edition. Insulation to be used must be as tested in the manufacturers test. Alternatives are not acceptable. The performance of the kitchen extract rating, is taken from thermocouples inside the ductwork inside the furnace, declared in a classification report EN13501-3.

All kitchen extract ducting must be accessible for cleaning and inspection purpose and have a Thor Duct® cleaning door (to the same fire rating, and tested in the proposed system) installed every 2 linear meters as stated in DW172:2018 2nd Edition. The cleaning doors must be as tested in the system.

All ductwork must have classification for testing outside (A) and inside (B) in both a horizontal and vertical position. All ductwork rated “S” for low leakage. A Classification report to EN13501-3 must be provided. Insulation ratings must be both type B and Type A. All kitchen extract ductwork will be tested in a flexible wall and be suitable for installation in stud partition, block wall and concrete floor.

All Kitchen Extract is to be installed under a third-party certifier such as Firas as identified in ASFP TGD 18.

For Fire Rated Duct 

for applications other than kitchen and smoke, the suggested specification can be written as follows:

All fire rated and pressurisation ductwork will be to standard prEN15871 and tested to EN1366‑1 vertically and horizontally for type A (fire outside) and type B (fire inside).

All ductwork rated “S” for low leakage. All fire rated ductwork will be tested in a flexible wall and be suitable for installation in stud partition, block wall and concrete floor. The performance of the ductwork, Integrity (E) and or Insulation (I) must be determined based on the compartment requirements, giving consideration to the performance required of the wall being crossed.

A Classification report to EN13501-3 must be provided.

All Fire Rated Ductwork is to be installed under a third-party certifier such as Firas as identified in the ASFP TGD 18.