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ASTM E1745 and ASTM E84- What’s the difference?

Posted by Nana Hinsley on Thu, Jan 09, 2014 @ 12:50

ASTM E1745 has nothing to do with ASTM E 84!  Vapor Barriers  also known as Vapor Retarders,  are subjected to a test known as ASTM E1745 to determine if the vapor barrier/retarder will perform well under certain conditions. ASTM E84 is looking at the surface burning behavior of a building material when it is exposed to flames.

Let’s look at ASTM E 1745 first. ASTM E1745 is the standard specification for water vapor retarders used in contact with soil or granular fill under concrete.  ASTM E 1745 covers flexible, performed sheet membrane. The values are stated in inch-pound units.   Vapor barriers have a very important role in the building industry. They are responsible for retarding water vapors that rise out of the earth headed to ruin the flooring above. The water can cause warping of wood floors, break down the adhesion, or worse yet, rot carpeting- allowing for mold to grow. One can quickly summize why it is critical to have the proper vapor retarder/ vapor barrier that will do what it was intended to do! There are times when contractors will try to save money by using a plastic liner that is not intended to retard water. Common construction grade plastics that are 4,6 or even 10 mil polyethylene that are made from low grades of polyethylene resin and post consumer recycled materials will cause inconsistencies in the physical strength and permeability of the liner. No one will see what is used once the building is built. That is why certain architects and engineers specify liners that meet ASTM E 1745.  Vapor retarders need to stay intact and resist attach from organisms in the soil and chemicals. They must also be strong enough to withstand construction traffic during installation.  They cannot be susceptible to punctures.  This is why ASTM E 1745 measures the physical characteristics such as puncture resistance, tensile strength and moisture vapor permeability.

There are three performance classes are outlined A, B and C (with Class A being the strongest). Permeance (how much water or vapor that passes through) levels are the same for each class. Tensile Strength and Puncture Resistance change with each class. ASTM E 1745 refers to ASTM E 154 "Standard Test Methods for Water Vapor Retarders Used in Contact with Earth Under Concrete Slabs, On Walls or as Ground covering crawl spaces." These test methods evaluate * Water-Vapor Transmission of Material as Received * Water-Vapor Transmission after Wetting and Drying and after Long- Time Soaking * Tensile Strength * Resistance to Puncture *


As this chart indicates, a Class A liner is stronger across the board than an Class C vapor retarder.  So how do you decide which one to use?  It depends on the installation scenario. If there is a great deal of sharp rocks versus if the vapor retarder is going into a wall- there is a big difference there.  Vapor Retarders control the building envelope from mold, condensation and degradation.  They are used in both walls and ceilings to effectively control both air infiltration and water vapor migration.

Standard 6 mil plastic sheeting that has not under-gone any testing in most cases will not hold up over time.

Click here to visit vapor retarders for Crawlspaces, or here for vapor barriers for under-slab vapor barrier applications

ASTM E84 also known as the Steiner Tunnel Test looks at the surface burning characteristics (burn behavior) of building materials when it is exposed to flames. It only provides a comparative measure of the surface flame spread and smoke density measurements with a select grade of red oak and fiber-cement board under specific fire exposure conditions. This test method measures flame growth on the underside of a horizontal surface using the Steiner tunnel test. ASTM E84 does not measure heat transmission through a tested surface.   For example, what is the flame spread and smoke density when flames hit a ceiling?  Flame spread and smoke developed index are reported. However, there is not necessarily a relationship between these two measurements. The resulting values are stated in inch-pound units, which is to be regarded as standard.  This standard is used to measure and describe the response of materials, products, or assemblies to heat and flame under controlled conditions. The test does not assess the fire-hazard or fire-risk assessment of the materials, products, or assemblies under actual fire conditions.

Interior designers are well aware of ASTM E-84 because of the materials they use to decorate commercial facilities.  Products applied to the walls, ceilings and other structural elements including columns all come into play.


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Tags: ASTME-84, ASTME 1745, Steiner Tunnel Test, Burn Test

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