Exposed Housewap (Tyvek) At Interior Surfaces

[Michael Thomas]

Is exposed Tyvek allowed at the interior (for example, at an insulated basement stud-wall)?

All I could find was this:

DuPont™ Tyvek® is combustible and should be protected from a flame and other high heat sources. If the temperature of DuPont™ Tyvek® reaches 750°F (400°C), it will burn and the fire may spread and fall away from the point of ignition. For more information call 1-800-44-TYVEK. DuPont™ Tyvek® carries a Class I or NFPA Class A fire rating for flame spread and smoke developed index as measured by ASTM E-84.

- Frequently Asked Questions (http://www2.dupont.com/Tyvek_Weatherization/en_US/tech_info/faqs_architects.html)

I do know that Tyvek clothing is flammable, and not recommended for applications such as welding unless specially coated, and that special Tyvek is available for applications requiring lower flame spread.

[Jerry Peck]

Is exposed Tyvek allowed at the interior (for example, at an insulated basement stud-wall)?

All I could find was this:

DuPont™ Tyvek® is combustible and should be protected from a flame and other high heat sources. If the temperature of DuPont™ Tyvek® reaches 750°F (400°C), it will burn and the fire may spread and fall away from the point of ignition. For more information call 1-800-44-TYVEK. DuPont™ Tyvek® carries a Class I or NFPA Class A fire rating for flame spread and smoke developed index as measured by ASTM E-84.


Michael,

Would you ... do you ... write up faced insulation with exposed facing and which has a similar, or even less alarming, statement of not being left exposed as it will burn?

[Michael Thomas]

Michael,

Would you ... do you ... write up faced insulation with exposed facing and which has a similar, or even less alarming, statement of not being left exposed as it will burn?

Of course, but I would prefer to find an explicit prohibition, like that printed on paper and foil facing, that I can reference in a report.

[Jerry Peck]

First, it is intended to be exposed to UV for only up to 4 months - being exposed in basement walls where there are windows which allow daylight in also allows the UV in that daylight to enter and strike the walls too. There are also other sources of UV, thus that may be required to be protected from those sources also.

Second, there is flame spread and smoke density, however, Tyvek passes that test: wall and ceiling finishes are limited to a flame-spread of not greater than 200 and a smoke developed of not greater than 450 (see IRC R315.1 and R315.2), as tested in accordance with ASTM E 84 (IRC 315.3), and Tyvek was tested as "8. Surface Burning Characteristics: Class A, when tested in accordance with ASTM E84. Flame Spread: 15, Smoke Developed: 15" according to their published information ( http://www2.dupont.com/Tyvek_Weatherization/en_US/assets/downloads/HomeWrap_product_specs.doc ).

I would write it up as not being installed in accordance with the intended use and installation (underlining is mine "A. Install weather barrier over exterior face of exterior wall substrate in accordance with manufacturer recommendations.") of the installation instruction instructions, note the information you found which refers to "it will burn and the fire may spread and fall away from the point of ignition", and recommend that it be covered with an approved building material, unless documentation from the manufacturer is provided which states that it may be installed as installed.