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

Water, Water Everywhere and Not a Drop to Drink: Practical Building Science to Keep Walls Dry

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

Construction Details for the Use of Foam Plastic Insulating Sheathing (FPIS) in Light-Frame Construction

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

IRC Wall Bracing: A Guide for Builders, Designers and Plan Reviewers

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.

Vinyl Siding Over FPIS 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. 

Attachment of Exterior Wall Coverings Through Foam Plastic Insulating Sheathing (FPIS) to Wood Wall Framing Report

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

Thermal Bridging in Building Thermal Envelope Assemblies: Repetitive Metal Penetrations Presentation

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

Best Practices

Foam Plastic Insulating Sheathing Used as a Water-Resistive Barrier System Installation Guide

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

Construction Guide: Next Generation High Performance 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.

BSI-120: Understanding Walls*

In August 2004, the ASHRAE Journal ran Joseph Lstiburek's paper enttitled “Understanding Vapor Barriers.”  After almost two decades, he has updated it to focus on rain and air control as well as vapor control – all things that “walls” need to do – hence the revised title, “Understanding Walls.”

Incorporating Thick Layers of Exterior Rigid Insulation on Walls

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

Attachment of Exterior Wall Coverings Through FPIS

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

Energy Code Math Lesson: Why an R-25 Wall is Not Equal to a R-20+5ci

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.

Practical Research

NYSERDA Fastening Systems for Continuous Insulation

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. 

Model Moisture Control Guidelines for Light-Frame Walls: A Building Code Supplement for Builders, Designers, & Bldg Officials

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.

Assessment of Water Vapor Control Methods for Modern Insulated Light-Frame Wall Assemblies Research Report

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

Cladding Attachment through FPIS Research Report

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).

Repetitive Metal Penetrations Research Report

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.

Air Space R-value Research Report

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.

Additional Information

Movement of Cladding Attached through FPIS - DOE Report

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