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Last Updated: , Created: Sunday, October 29th, 2023

Residential Window Installation with Pressure Equalization

Research projects by George Brown College,
Red River College and Jon Eakes

studying pressure equilization in low rise wood frame residential construction 



Link to PDF: Pressure Equalization final report revised January 2024 --  George Brown College. 

Link to Fenestration Canada's January 18th 2024 webinar on the GBC final report, which includes more photos and videos on the project.

Link to my Window Research Newsletter on the final report from George Brown College



Link to Fenestration Canada's March 28th 2024 webinar on the Red River College (BETAC) final report.

Link to my Window Research Newsletter on the final report from Red River College



Link to the original 2019 introduction promoting this research, including the full video of my shop model of the dynamics of window/wall interface pressure equalization.

Link to Instute for Research in Construction (IRC-NRC) Construction Technology Update #76 : Window Sill Details for Effective Drainage of Water

Link to Instute for Research in Construction (IRC-NRC) Construction Technology Update #80 : Window Installation Details for Effective Sealing Practice



Si vous souhaitez consulter les documents de CTU (Solution constructive) en français directement à partir du site web du CNRC, rendez-vous sur et recherchez "Solution Constructive" de 2011 à 2013 pour no. 76 et no. 80.

Lien à PDF en français: Rapport final de la recherche sur l'interface mur-fenêtre du George Brown College janvier 2024  --  George Brown College. 

Link to the archives of this Research Newsletter or to sign-up to receive the Window/Wall Interface Research Newsletter.


Links to come soon:

Link to Thermal penality study on absence of insulation in the window/wall interface -- BETAC Final Report when it is released, but it is discussed in the Fenestration Canada webinar and Newsletter linked above.

Link to Post Research Developments.



 Our research is focused uniquely on pressure equalization and drainage in the window/wall interface of low rise residential construction.  Joe Lstiburek throws his support into this effort by providing us with his 2014 article on exactly the same principles applied to low rise residential window profiles.  These two together can lead to a unified systems approach to durable moisture control in low-rise residential window installations.  BSI-004: Drainage, Holes and Moderation


Abstract from George Brown College report

From 2005 to 2010 the IRC of the National Research Council of Canada undertook extensive research on moisture penetration in standard low rise residential window installations. Two Construction Technology Updates, summaries of the heavily detailed research reports, directed attention to a fundamental error of standard practice, trying to stop the wind and the rain at the same place.  Many questions were left undeveloped when the three subsequent planned Updates were abandoned. 

In 2019-2020, Jon Eakes raised the issue at numerous window conventions, suggesting that deviations from standard face sealing techniques, allowed for in the CSA-A440.4 window installation standard, could open the door to simpler, more durable and maintenance free window installations.  This led to the possibility of trying to answer some of those undeveloped questions in the large climate chambers of BETAC, a department of Red River College in Winnipeg, and the much smaller climate chamber at George Brown College in Toronto.  This is a report on the very narrow research undertaken at George Brown College, specifically to demonstrate the applicability of rain screen type pressure equalization in residential low-rise construction. 

The premise to be proved

In a window/wall interface, totally air sealed on the interior with no water sealing or air sealing on the outside, but with simple baffle like obstructions between the wind driven rain and the interface, when the wind is allowed to flow into the sill area of the drainage paths, pressure equalization does effectively remove the driving force from the rain entry, directing the rain penetration into vertical drainage down and out at the sill.  The dictum to “not try to stop the wind and the water at the same plane” is satisfied and there is no driving force to push water into the wall. 

Although this project, long stalled by the pandemic, did not produce quantitative data on moisture control, it did confirm visually the possibility of applying “rain screen type” pressure equalization to the narrow space between the window and the wall, the window/wall interface.

It is hoped that this confirmation, combined with the results from BETAC of measuring the heat loss penalty for reducing the insulation used in window installations to provide for this pressurized drainage path, could lead to quantitative testing searching for the optimum configurations for insulation, drainage layer size and details on providing effective wind entry at the sill. 


Keywords: Installation, Windows, Innovations, Insulation, Pressure Equalization, Research

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