It’s also important to note that polyiso’s closed-cell foam structure is responsible for its high R-value per inch and inherent resistance to moisture intrusion, which can be a critical factor in the long-term durability of roof assemblies. In addition, polyiso also demonstrates code-required fire performance and is the only foam plastic insulation product approved for direct application to steel decks in many assemblies, providing additional design flexibility for commercial roofing projects. 

A versatile option, polyiso rigid roof insulation is available in multiple forms, including flat stock boards and polyiso tapered insulation. Additionally, high-density (HD) polyiso roof cover boards are growing in popularity due to their ease of use and resistance to impact and wind uplift forces. This gives designers a multi-use solution that can accommodate project-specific challenges and requirements while enhancing whole building energy efficiency. 

For instance, when the roof deck alone does not provide adequate slope or instances when the existing building structure has insufficient positive drainage, polyiso tapered roof insulation can be incorporated to improve slope-to-drain and optimize roof system performance. In application, polyiso tapered insulation systems can help designers shed or drain water, directing it toward primary and secondary drains. This reduces the risk of standing or ponding water, which can create additional maintenance and repair costs, significantly shorten the roofs service life, and potentially cause premature roof failure. Because tapered roof insulation systems support code-compliant water management strategies and create positive drainage in any design or in-field condition, they will improve the long-term performance of the roof system and can ultimately extend its lifespan. 

HD polyiso roof cover boards provide another example of polyiso’s versatility in commercial roof applications. Consider how commercial roof assemblies are regularly subjected to extreme weather, foot traffic, rooftop equipment loads and ongoing maintenance activity, all of which can place stress on the roofing system over time. Enhanced durability and strength is key here. HD polyiso roof cover boards provide a strong, durable and lightweight substrate for roofing membranes capable of supporting these types of activities while protecting underlying insulation. HD polyiso roof cover boards, versus a more traditional cover board (e.g., gypsum board), offer next-level protection because they combine compressive strength and added thermal resistance (R-2.5 at 1/2” thicknesses) in a single product. 

Polyiso roof insulation and cover boards are also backed by industry-average Environmental Product Declarations (EPDs) that provide design and construction professionals with the information they need to meet client sustainability goals and green building rating system requirements. 

Ultimately, due to polyiso’s wide use in low-slope commercial roofing systems, these types of polyiso roofing products can offer designers numerous benefits in application: long-term thermal performance to meet modern energy codes, versatility to accommodate project-by-project complexities, and compatibility with other roof system components. 

Explore PIMA’s 100-Series Technical Bulletins to learn more about how polyiso can be used in roofs to create code-compliant, energy-efficient, resilient buildings for the future: https://www.polyiso.org/page/100SeriesRoofing