Moisture Barrier Testing and Evaluation

Moisture Barrier and Underlayment


Chapter 14, section 1403.2, of the 2012 International Building Code (IBC), which covers weather protection of exterior walls, states that “Exterior walls shall provide the building with a weather-resistant exterior wall envelope. The exterior wall envelope shall include flashing, as described in Section 1405.4. The exterior wall envelope shall be designed and constructed in such a manner as to prevent the accumulation of water within the wall assembly by providing a water-resistant barrier behind the exterior veneer, as described in Section 1404.2, and a means for draining water that enters the assembly to the exterior. Protection against condensation in the exterior wall assembly shall be provided in accordance with Section 1405.3.”

Section 1404.2 defines a water resistive barrier as “a minimum of one layer of No.15 asphalt felt, complying with ASTM D226 for Type 1 felt or other approved materials.”

Housewraps include all types of synthetic materials installed over the sheeting and behind the exterior siding of a house to protect the wall assembly from rain while still allowing water vapor to pass through to the exterior. Housewraps have become the other approved materials that are replacing asphalt felt, and NTA is able to test new housewrap materials for code compliance, as well.

Roof Underlayments

Chapter 15 of the 2012 International Building Code, which covers roof assemblies and rooftop structures, defines a roof underlayment as “One or more layers of felt, sheathing paper, nonbituminous saturated felt or other approved material over which a steep-slope roof covering is applied.”Section 1507.2.3, which covers the requirements for roof underlayments states “Unless otherwise noted, required underlayment shall conform to ASTM D226 Type 1, ASTM D4869 Type 1, or ASTM D6757.” NTA can help! NTA can even perform ASTM E96 to test the permeability of materials for water vapor transmission.

What NTA can do

NTA is one of the only testing laboratories that offers manufacturers a single-stop solution for all testing, certification, inspection and follow-up services. Having all required services performed by a single vendor saves you a significant amount of time and money.

NTA is accredited by the International Accreditation Service (IAS) under ISO/IEC 17025 to test, ISO/IEC 17020 to inspect and under ISO/IEC 17065 to verify the code compliance moisture barriers and underlayments.

NTA performs the following tests:

  • ASTM D226: Standard Specifications for Asphalt-Saturatede Organic Felt Used in Roofing and Waterproofing outlines minimum requirements for both housewraps and underlayments. To meet these requirements, some tests include:
  • ASTM D4869: Standard Specification for Asphalt-Saturated Organic Felt Underlayment Used in Steep Slope Roofing outlines minimum requirements for underlayments. To meet these requirements, some tests include:
    • Tear strength
    • Pliability
    • Loss of heating
    • Liquid water transmission
    • Breaking strength
    • ICC—ES AC38
    • ICC—ES AC48

For more information about our testing housewraps or moisture barriers, contact us.

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