ICC-ES AC188
Full Name
ICC-ES AC188 – Acceptance Criteria for Roof Underlayments
Scope
ICC-ES AC188 outlines the acceptance criteria for evaluating membrane materials used as alternative roofing underlayments. These can be either self-adhering or mechanically attached and installed over solid or closely spaced roof sheathing. The criteria aim to ensure the underlayment’s performance and suitability for its intended use in protecting the building envelope.
Key areas covered by AC188 include:
- Material properties: defining the acceptable types of membrane materials (e.g., asphalt-saturated, synthetic) and their required physical properties such as tensile strength, tear resistance, puncture resistance, and dimensional stability.
- Water resistance: evaluating the underlayment’s ability to resist water penetration, including testing for water vapor transmission and resistance to hydrostatic pressure, which is crucial for preventing moisture-related issues in the roof assembly.
- Durability: assessing the underlayment’s resistance to weathering, UV radiation, and temperature extremes to ensure it maintains its performance over time and under various environmental conditions.
- Fire resistance: determining the fire classification of the underlayment according to relevant standards like ASTM E108 or UL 790, ensuring compliance with building code requirements.
- Compatibility: ensuring the underlayment is compatible with different types of roofing materials and adhesives, preventing any adverse reactions or interactions that could compromise the roof system’s integrity.
By adhering to AC188, manufacturers can demonstrate that their roof underlayment products meet the necessary performance and safety standards, giving building officials, designers, and contractors confidence in their use for protecting roofs from moisture and other environmental factors.
Resources
Keywords
roof underlayment; acceptance criteria; membrane materials; tensile strength; tear resistance; puncture resistance; water resistance; water vapor transmission; hydrostatic pressure; fire resistance; weathering; UV resistance; compatibility