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

Residential Window Installation with Pressure Equalization

A research project by George Brown College and Jon Eakes


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

Links to come soon:

Link to videos and photos of GBC pressure equalization study.

Link to Thermal penality for taking insulation space to create the drainage planes -- BETAC Final Report

Link to Post Research Developments.


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 residential window installations.  Two Construction Technology Updates 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 unanswered 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 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 unanswered 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, Pressure Equalization

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