Making the situation even more complicated:
“Since the adoption of NFPA 285, many hundreds of wall assemblies have been tested with no specific guidance regarding joint placement. These tests have provided the design professional a broad range of test reports covering assemblies with anything from no vertical joints to the-now mandatory-vertical joint in the center of the window opening and with horizontal joints located practically anywhere on the wall assembly. Out of the hundreds of tests run over the past 20-plus years, only a small fraction have been done with joints in the newly defined locations. Each of these wall assemblies have met the test criteria at a test cost in the neighborhood of $25,000 or more when combining lab fees plus material and labor costs to construct the wall.
When the new NFPA 285 standard is published, most existing tests will no longer meet the requirements due to the new joint requirements, and a new test will need to be run on a wall assembly that has been accepted for decades. With only three or four recognized test facilities in North America, there will be a considerable backlog for new wall design tests, and to retest walls that were once considered acceptable. While the IBC may not reference the new test version of NFPA 285 until the 2021 code is published, architectural specifications can begin requiring these new test results almost as soon as the test standard is published.”
Quote taken from article by Paul Deffenbaugh Posted Metal Construction News July 04, 2017
Recognizing this complexity, some initial efforts are being made to compile a database of 285 fire-tested assemblies. Meanwhile some proactive material manufactures are trying to offer a large selection of compliant assemblies that use their products for designers to choose from.
This is what the architects need at the end of the day,” affirms Beitel. “How soon and how that will come about, I don’t know as it is not a simple process, but the construction industry understands that we have to get that together.”
One tool which architects can potentially use is an engineering judgment analysis letter furnished by a reputable code expert. This involves bringing in such a consultant and inquiring as to whether individual products which passed NFPA 285 in separate tests, could be combined together in one assembly and not officially require testing, based upon the expert’s opinion that the new combination would theoretically provide acceptable life safety levels.
“It is possible and reasonable to make such judgments,” notes Beitel. “For example, if a steel stud gypsum wall was tested and passed, and now the architect wants to put it on a concrete masonry unit, the code officials would probably accept this.”
At the same time, such an engineering analysis must come from a consultant who is intimately familiar with the 285 test and is knowledgeable in the field. And secondly, the onus lies on the architect and consultant to convince the local AHJs that the NFPA 285 test can be bypassed in this instance.
“This can save a considerable amount of money over a custom 285 test. Of course, if a full test is going to be required, fire safety consultants are essential to get to approval without experimenting with the materials too much,” adds Altenhofen.
Since the legal responsibility doesn’t fall on the code officials, but rather the consultant and the party who commissioned the consultant, the AHJs are often willing to consider such well-founded exemptions, or specific exemptions which will be included in future versions of the IBC, such as the WRB exemptions in the 2015 IBC.
Other than recruiting the services of such a consultant, as mentioned, architects don’t have the benefit of a “cheat sheet” at this time and are really being forced to do their homework. At the same time, some manufacturers are more progressive than others in providing specifiers with such a chart instructing how to build a NFPA 285 compliant wall assembly based upon their testing data.
In addition to the NFPA 285 wall assembly test, relevant combustible components must also pass a series of material tests, per the International Building Code.
“It is important to understand the how material tests differ from assembly tests on how they are performed and how they are required by code,” says Benjamin Meyer, science architect, DuPont Building Innovations, Richmond, Virginia.
While, in many cases, the manufacturers take care of these tests, architects need to be familiar with the various ASTM tests and double check that a given product is compliant.
Designing Without NFPA 285
As noted earlier, if a wall assembly is designed without foam plastics and is less than 40 feet above grade, then NFPA 285 testing is not required. In addition, NFPA 285 compliance is not required for Type V Combustible Wall construction as the IBC gives prescriptive requirements instead. Previously, NFPA 285 compliance was not required for a wall of any height, comprised entirely of noncombustible materials, but the recent addition of the WRB trigger to the 2012 IBC has put a logistical hold on this option.
In terms of the WRB exceptions coming up in the 2015 IBC, although this code version won’t be adopted for some time—in fact, as late as 2018 in some jurisdictions—the document is available for reference at this time and some local authorities may choose to implement it, particularly those who are approached by the National Institute of Building Science and the Building Enclosure Technology and Environment Council—with support from the American Institute of Architects—who are actively lobbying the IBC and local AHJs that wall assemblies can be built to acceptable life safety standards without the full requirements of NFPA 285.
In particular, the group proposed changes to the foam insulation and WRB sections of NFPA 285 for the 2015 IBC. Although the foam proposals were rejected, the group achieved partial success with WRBs.
The specific claim made by NIBS/BETEC in the WRB proposal reads as follows:
“There are materials that are available, tried and tested by long-term proven history of performance as weather barriers that are not able to meet the standards in this test. Section 1403.2 of the IBC requires weather-resistive barriers while Section 1403.5 requires them to be tested to a standard if they contain a combustible water resistive barrier that many materials that are traditionally used and have proven their value can’t meet.
Section 2603.5 establishes requirements for protection and testing of combustible water resistive barriers that include foam plastic insulation, so Section 1403.5 is not necessary for those products. Given that 75% of construction litigation relates to water leakage suggests that this paragraph should be deleted or we are likely to face significant problems in the future with the failure of exterior water barriers.”
A New Reality
Although NIBS and BETEC are planning to continue lobbying the IBC, and it will take time until all the local AHJs update their codes to incorporate the 2012 IBC, or at least base their next commercial building code on the latest IBC, the fact remains that the construction industry is entering a new NFPA 285 reality. These stringent fire protection provisions coupled with stricter energy codes are anticipated to shake things up in terms of the way wall assemblies will be specified moving forward.
Tasked with this challenge, architects will need to be knowledgeable about the standard, how it works, when it is applied, and when it can be avoided. Meanwhile, manufacturers who want their products to be specified will have to work as an ally to designers by taking on the onus of testing, where possible, and openly furnish architects with test-compliant information.
This document draws out some of the main points from the NBC regarding fire protection of exterior walls incorporating combustible components, claddings or cladding elements. Foamed plastic insulations, which typically have flame spread ratings between 200 and 500 (depending upon the type), cannot be left exposed anywhere on the interior or exterior of a building. For exterior applications, foamed plastics used as part of an exterior wall must be tested to, and comply with, the full scale fire test CAN/ULC-S134. Materials must comply with CAN/ULC-S102 “Standard for Surface Burning Characteristics of Building Materials and Assemblies” in preference to ASTM E84 “Standard for Surface Burning Characteristics of Building Materials”.
There are a number of provisions within the NBC that relate to fire protection of exterior walls incorporating combustible components, claddings or cladding elements. Section 18.104.22.168. addresses the protection of combustible components of exterior walls from external fire attack. Section 22.214.171.124. ‘Combustible Components for Exterior Walls’ require exterior non-load bearing wall assemblies that include combustible components are permitted to be used in a building required to be of noncombustible construction provided that:
(a) the building is (i) not more than 3 storeys in height, or (ii) sprinklered throughout,
(b) the interior surfaces of the wall assembly are protected by an approved thermal barrier and
(c) the wall assembly satisfies specific criteria when subjected to testing in conformance with CAN/ULC-S134, “Fire Test of Exterior Wall Assemblies.”
Conversely, 126.96.36.199. addresses the protection of combustible insulation within the wall, or used as an interior finish, from interior fire spread. Section 188.8.131.52. applies to combustible insulation and its protection. Foamed plastics having a flame-spread rating of not more than 500 may be allowed in a building required to be of noncombustible construction when protected by an approved thermal barrier.
Section 184.108.40.206. applies to minimum construction requirements for exposing building faces based on the occupancy classification of the building. The fire resistance ratings which are required will depend on the area of unprotected openings as a percentage of the exposed building face and the spatial separation to adjacent structures.
Section 220.127.116.11. states that foamed plastic insulation used in exterior walls greater than 3 stories where the maximum area of unprotected openings is permitted to be greater than 10% must be protected by a minimum thickness of 25 mm concrete or masonry or pass a modified version of the CAN/ULC-S101 fire endurance test, as well as other performance requirements.
The performance of exterior walls during fire exposure is a critical element of building construction. Steel, concrete, masonry, gypsum and stone wool are the materials of choice when fire performance and the presence of combustible materials within the building envelope are of concern.
The federal government has been aggressively raising the bar on energy-efficient building standards, making this sustainable trend a requirement.
The DOE has mandated that by October 18, 2013, all states must certify that they will adopt a commercial building energy code that meets or exceeds ASHRAE Standard 90.1-2010. This updated standard triggers the need for a substantial change to the design of wall assemblies in new commercial construction.
National Energy Code of Canada 2015
The 2012 International Energy Conservation Code (IECC), which adopts ASHRAE Standard 90.1-2010, has increased the minimum thickness required for continuous insulation for most commercial wall assemblies in climate zones 3 – 8, approximately 90 percent of the United States.
Map of the US climate zones according to the IECC
Whereas previous codes have only alluded to general air sealing of the building envelope, the 2012 IECC now includes specific, mandatory provisions for Air Barriers in Climate Zones 4-8. These requirements may be met through the use of approved materials, approved assemblies, or whole building air leakage testing (ASTM E779). As more states adopt this code, these provisions will become mandatory for designers of commercial buildings in those jurisdictions.
Typically revised every three years, the IECC is part of the International Building Code (IBC) and is the governing commercial code section for building design and material requirements related to energy efficiency.
The IECC divides the United States into eight climate zones, each with specific requirements for the type, placement and amount of insulating materials – both cavity and continuous – in the wall assembly. Several versions of the IECC are currently in effect across the country, making it vital to be aware of which version is adopted by the state or local jurisdiction in which a project is located.
Each update of ASHRAE Standard 90.1 and IECC adoption has increased the amount of continuous insulation required in commercial buildings.
The latest ASHRAE Standard 189.1 (Standard for the Design of High Performance Green Buildings) adds the requirement for an air barrier as well as requiring and increasing the thickness of CI in ALL climate zones (1-8).
There is little doubt that future codes will be even more stringent when pertaining to energy efficiency.