Code Conforming Design – NFPA 285 & Exterior Wall Coverings

Originally published by the following source: SBC MagazineOctober 24, 2018
by Sean Shields and Kirk Grundahl, P.E.

   

The evidence supporting the effectiveness of NFPA 285 is very strong and history bears out this conclusion. Since its introduction in 1988, the NFPA 285 test has remained relatively unchanged, and 30 years of use has generated no evidence of any evaluation of fire propagation characteristics or life safety deficiencies.

With recent high profile international fires, such as Grenfell where NFPA 285 does not apply and obviously was not used, there has been heightened concern about the fire performance of exterior facades or as they are called in the building code "exterior wall coverings."

The International Building Code (IBC) defines exterior wall covering in Chapter 2 as follows:

 

 

Exterior is not an IBC-defined term, therefore exterior means:

 

 

Here are all the Chapter 2 definitions that use this as a defined term to provide the implied context.

 

 

In the U.S., the use of sprinklers and NFPA 285 to assess exterior wall assembly performance is working well. The available data indicates that if there is a need, it is to ensure compliance with the sections of the IBC which relate to exterior wall assembly performance. This includes but is not limited to fire endurance assembly testing using ASTM E119NFPA 285 and any relevant engineering analysis is a very safe approach (also known as “accepted engineering practice”). This is a very safe approach to code compliance.

The NFPA 285 test then, per the historical use of Section 2306.9, supersedes all individual material testing, such as ASTM E84 for the plastic component. The fire engineering reason for this is that the NFPA 285 test is a much more rigorous and application appropriate test method.

Why? ASTM E84 is a very simple flame spread test that places an individual product horizontally in a tunnel and provides flame impingement. There are foam plastic products that have passed the horizontal ASTM E84, which would never pass the vertical NFPA 285, vertical placement being the key. In other words, NFPA 285 performance is well known in the fire engineering community to supersede the need for small scale testing of any of the assembly parts and pieces. It is simply the best test to use for evaluating the suitability of exterior, non-load bearing wall assemblies, is wall assembly application specific and has more than 30 years of good performance history.

It seems clear from all the information available that if designers, builders and installers perform in a manner that conforms with the requirements of the IBC, the 30 years of demonstrated effective and safe performance when NFPA 285 and IBC Chapter 26 is used, will continue. NFPA 285 testing along with engineering analysis using this test data and additional test data calibrating fire-engineering modeling isn’t the problem; it is the solution! 

For additional information, please review the following articles:

  1. Applying the IBC: What Does 'Exterior' Mean in Chapter 14?
  2. Code Conforming Design – NFPA 285 & Section 2603.9
  3. NFPA 285 and Code Conforming Design – Reliable or Not?
  4. Understanding Fire Safety and the Use of Foam Sheathing
  5. ICC Provides Perspective on Combustible 'Cladding Systems'
  6. Post Grenfell, Do You Know the Code and Your Cladding Options?
  7. Would Smoke Alarms and Sprinklers Have Saved Grenfell's Installed Cladding?
  8. London's Grenfell Fire: Will Plastics Be Inappropriately Blamed?