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Before installing the windows, the window rough openings are sealed with a liquid-applied flashing that provides a seamless moisture and air barrier to protect the wall from water intrusion.

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If spray foam is used to air seal over backer rod around the window’s rough opening, foam should entirely cover the rod and let dry then trimmed flush to frame

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Triple-Pane windows can be used as a tradeoff for continuous wall insulation or stricter air sealing targets when showing compliance with the 2021 IECC using the UA path

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Once window trim is removed around window, any fibrous insulation is removed and the opening is brushed before installing canned foam or backer rod and caulk to air seal the rough openings

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A dormer with an openable window (not shown) can provide access to the roof if flood waters rise too high and too quickly; the dormer should be properly insulated, flashed, and air sealed

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Right – This crawlspace window was completely sealed off on the inside and outside with air barrier and water-proof materials and the window well was filled in to an above-grade height to prevent bulk water from entering the crawlspace

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Why Seal and Insulate?

Reference

Introductory guide to air sealing the envelope of a home to reduce wasted energy and save on energy costs.

Wrong - Basement window not sealed.

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Fully Sealed Continuous Weather Resistance Barrier (3)

Video

Video describing how to fully seal a continuous weather resistance barrier.

Right - All gaps and joints are sealed to provide an airtight construction.

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Right - House wrap is sealed to window flange with liquid-applied sealant.

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Caulk applied against the backer rod to seal a window rough opening

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Install weatherstripping in the framing of openable doors and windows; use caulk to seal seams in and around trim.

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Wrong - This IR image shows air leakage around a window.

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Right - Seams in coated sheathing and joints around window are properly sealed and flashed with tape and all nail holes are covered with paint-on sealant.

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An energy rater will check for dry rot and moisture problems as well as air leakage around windows and doors.

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Builders use an infrared camera to “see” heat flow and air leakage around a window during construction.

Image

Right - New flashing has been installed to complete the air and water control layers at the window openings of this wall retrofit that includes insulating the wall cavities with spray foam

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Window and Door Rough Openings

Video

Video describing how to air-seal around window and door rough openings.

Moisture Management in Residential Construction Series - Building Enclosure: Window Installation

Video

Video describing the installation of windows to be air- and water-tight, including recommendations on flashing, air-sealing, and insulation, from Home Innovation Research Labs

Skylight Shaft Walls

Guide

Guide describing insulation techniques for skylight shaft walls.

DOE ZERH HIA 2013 Case Study: Weiss Building & Development, System House, River Forest, IL

Case Study

Case study describing a 4,763 ft2 certified Passive House that achieved HERS 27 without PV through the construction of R-54 walls that use ICF plus fiberglass cavity insulation, an R-100 vented attic, extensive air sealing and flashing, triple-pane windows, ductless heat pumps, and solar hot water.

Before installing the windows, the window rough openings are sealed with a liquid-applied flashing that provides a seamless moisture and air barrier to protect the wall from water intrusion.

If spray foam is used to air seal over backer rod around the window’s rough opening, foam should entirely cover the rod and let dry then trimmed flush to frame

Triple-Pane windows can be used as a tradeoff for continuous wall insulation or stricter air sealing targets when showing compliance with the 2021 IECC using the UA path

Once window trim is removed around window, any fibrous insulation is removed and the opening is brushed before installing canned foam or backer rod and caulk to air seal the rough openings

A dormer with an openable window (not shown) can provide access to the roof if flood waters rise too high and too quickly; the dormer should be properly insulated, flashed, and air sealed

Right – This crawlspace window was completely sealed off on the inside and outside with air barrier and water-proof materials and the window well was filled in to an above-grade height to prevent bulk water from entering the crawlspace

Why Seal and Insulate?

Window not caulked or sealed

Wrong - Basement window not sealed.

Fully Sealed Continuous Weather Resistance Barrier (3)

Right - All gaps and joints are sealed to provide an airtight construction.

Right - House wrap is sealed to window flange with liquid-applied sealant.

Caulk applied against the backer rod to seal a window rough opening

Install weatherstripping in the framing of openable doors and windows; use caulk to seal seams in and around trim.

Wrong - This IR image shows air leakage around a window.

Right - Seams in coated sheathing and joints around window are properly sealed and flashed with tape and all nail holes are covered with paint-on sealant.

An energy rater will check for dry rot and moisture problems as well as air leakage around windows and doors.

Builders use an infrared camera to “see” heat flow and air leakage around a window during construction.

Right - New flashing has been installed to complete the air and water control layers at the window openings of this wall retrofit that includes insulating the wall cavities with spray foam

Window and Door Rough Openings

Moisture Management in Residential Construction Series - Building Enclosure: Window Installation

Skylight Shaft Walls

DOE ZERH HIA 2013 Case Study: Weiss Building & Development, System House, River Forest, IL

Weatherization Tips - How to Weatherize Doors

DOE ZERH HIA 2017 Case Study: Thrive Home Builders, Lowry Plan, Denver, CO

Existing Whole-House Solutions Case Study: SMUD's Energy Efficient Remodel Demonstration Project

Existing Whole-House Solutions Case Study: SMUD's Energy Efficient Remodel Demonstration Project: Sacramento, CA

DOE ZERH HIA 2013 Case Study - Dwell Development, Seattle, Washington

Existing Whole-House Solutions Case Study: Evaluation of a Multifamily Retrofit in Climate Zone 5, Boulder, Colorado

New Whole-House Solutions Case Study: The Performance House: A Cold Climate Challenge Home, Old Greenwich, Connecticut