Windows can easily coexist with exterior continuous insulation of many thicknesses. With a whole building analysis, increasing the level of continuous insulation can allow for larger windows while maintaining the same level of overall building thermal performance. Modern detailing methods improve moisture management around fenestration openings.

Tools & Education

Window Installation: Pan Flashing and Air-Sealing to Prevent Water Intrusion

This presentation addresses two practices with proven ability to improve water penetration resistance of fenestration product installation: Sill pans and flashing for rough opening drainage, and air-sealing of the interior side of the rough opening gap.

Best Practices

Incorporating Thick Layers of Exterior Rigid Insulation on Walls

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

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.

Practical Research

Water-Resistive Barriers: Assuring Consistent Assembly Water-Penetration Resistance

Summary of WRB water penetration testing requirements and recommendations for the fair treatment of WRB products based on one performance-based benchmark for water-penetration resistance of WRB assemblies.

Additional Information

Installing Windows with Foam Sheathing on a Wood-Frame Wall

DOE Building America report from 2005 on installing windows into walls with foam sheathing used as an integrated drainage plane

Musings of an Energy Nerd: Nailing Window Flanges Through Foam

This blog article captures the successful historic practice of installing flanged windows directly over foam sheathing, but also recognizes the utility of enhanced details when large/heavy windows or thick foam is used.

Continuous Insulation and Punched Openings: Windows Can Be A Pain

The water control layer of the wall has to connect to the water control layer of the window.