When it comes to walls, the use of continuous insulation can greatly improve performance and simplify design and installation. In particular, foam plastic insulating sheathing (FPIS) products can serve as an air barrier, water resistant barrier, control water vapor, and cut down on the detrimental effects of thermal bridging.

Tools & Education

This session, presented at IBS 2017, provides actionable prescriptive guidelines for integrated insulation and vapor control strategies. 

How to apply the IRC bracing provisions for code-compliant dwellings and how the IRC bracing provisions can be used to create maximum value in a diverse housing market.

Code-compliant details for the use of foam sheathing as thermal insulation in light frame construction. Available as a sealed code compliance report.

Requirements for installation of vinyl siding over foam sheathing in thicknesses up to 4" when used as thermal insulation in exterior walls. Available as sealed code compliance report. 

Cladding installation through foam sheathing used in wood frame exterior wall applications. Available as a sealed code compliance report. 

Discusses types of thermal bridges and their impacts as well as repetitive metal penetrations for cladding and component attachments. 

Best Practices

Step by step instructions on how to install foam sheathing as a WRB system

Guidance for the use of thick foam (>1-1/2") in wood frame buildings 

Installation guidance for cladding installation through foam sheathing used in light frame exterior wall applications

When a builder comes across an R20 + 5ci insulation requirement, it can be easy to think: R20 + 5ci? Why not just use R-25 in the cavity? This guide goes through the math comparing R20 + 5ci and R25 walls.

This guide from Building America addresses various means of applying foam sheathing on 2x4 wood framed walls in climate zones 3-5, including integration with other components (e.g., windows and cladding) for foam thicknesses up to 1-1/2”. It also addresses air barriers,  water vapor retarders, and use of foam sheathing as a WRB or in combination with a separate membrane WRB.

Additional Information

Research findings on the long-term performance of cladding attachments through foam sheathing. Covers fastening techniques, material expansion and contraction, and deflection (creep). 

Practical Research

A comprehensive assessment of the state-of-the-art of water vapor control for modern, code-compliant, light-frame wall assemblies.

Overview of current knowledge supporting the attachment of cladding through foam sheathing used in exterior wall assemblies to comply with the 2015 editions of the International Building Code (IBC) and the International Residential Code (IRC).

Provides data to help better understand the implications and support an equitable, performance-based treatment of thermal bridges for common building assembly conditions and variations.

As energy codes continue to become more stringent, the thickness of continuous installation has increased. This report examines problems and solutions for fastening systems where thick foam is used. 

This Research Report provides actionable guidelines to effectively consider, evaluate, and manage the balance of wetting and drying potential in common above-grade, light-frame wall assemblies in a broad range of climate conditions.

Airspace R-values should not be used to displace insulation materials required for energy code compliance unless the air spaces are properly constructed to have no air leakage, or the R-value is appropriately discounted for air-leakage.