Above the code: Fire testing for walls

Most wall cladding products in the United States are tested to the ASTM E84 standard.  This standard is referenced in building code by the NFPA (National Fire protection agency) and has been an accepted standard for many years.  

The test measures for two things: Flame Spread (how fast the fire travels) and Smoke Generation (how much smoke is created).  Both are very important when determining the fire safety of a product.  

How the test works

This test method measures flame growth and smoke development of a test specimen as it is suspended in a cement tunnel chamber. The flame source appears below the material and the test looks to measure how quickly flame spreads along the specimen and how much smoke is generated in the chamber.  

The flame spread is measured by eye, smoke development is measured by a photometer.  A product is given a rating based on its performance. 

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Not all results are apples to apples

The classification determines which areas the product can be installed in and provide a good idea of a product’s fire performance. Class 1 or A are used interchangeably depending on the specific building code.

There are a few deficiencies with the test method. This ASTM method does not require a specific substrate be used in the test. Because of this, some manufacturers will test on gypsum board, cement, or even calcium carbonate (an extremely fire resistant, chalk like material). Some manufacturers will not use any substrate at all (in this case they suspend the samples with chicken wire), this has an effect on the results and means that without the actual test report it’s not easy to get an apples to apples comparison. However, while the ASTM standard doesn’t require a substrate, the building code does. The building code requires that the material be tested on the substrate that will be used in the field, in most cases this is gypsum board/drywall. 

What to look for?

To be safe, choose products that have a Class 1 or A Rating on gypsum board/drywall. This is the most common substrate used in the field and represents a worst-case scenario. Any passing result on this substrate should also pass on cement board.  If the test substrate is not clear, specifiers should ask manufacturers for a copy of their test reports.  This is the best way to determine if a product will actually perform as a Class 1 or A product in the field.  

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Posted: 10/10/2016 6:49:28 PM by Jesse Wade | with 0 comments