FGIA Analysis October 2020July 27th, 2021 by Nathan Hobbs
Added Variables: New Installation Guidelines Help Installers Keep Brick in Place
By Rick Rinka
Despite its importance to window performance, installation quality is inherently variable—partly because so many factors go beyond just window type and mounting configurations (with and without mounting flanges). At the same time—particularly in replacement window installation— many variations of construction make it difficult to provide detailed instruction that addresses all possibilities.
Building largely on the foundational ASTM E2112 – 19c, Standard Practice for Installation of Exterior Windows, Doors and Skylights, which focuses on integrating the window with the weather-resistant barrier (WRB), FGIA/AAMA has developed standard installation methods for use under different examples. Currently the FGIA/FMA/WDMA Joint Replacement Window Task Group is also putting final touches on an additional standard installation practice—one that accounts for the installation of replacement block windows into an existing wall which has a brick veneer and a membrane/drainage system without removing any of the veneer.
Covering the Gamut
Provisionally titled Standard Practice for the Full Frame Replacement of Windows without Removal of Exterior Brick Wall Cladding, a new document also applies to a surface barrier system, or a wall system without a reliable membrane drainage system. It covers block frame windows not attached with a flange but which can employ an exterior frontal (non-attachment) flange.
The standard installation practice will help users determine which method is most appropriate to the type of project using a decision tree approach. A three-tiered assessment starts with an evaluation of existing conditions and constraints, followed by an assessment of the existing window type/configuration and material, and finally by an assessment of the wall façade and whether or not it will be removed. It guides the user to which installation methods and standards apply to four different window frame types. The new document addresses Type 4: full-frame replacement without removal of the brick veneer.
The new standard installation practice describes a water management strategy that directs moisture to the exterior façade via through-wall flashing at the sill. Detail is provided for flashing, especially the configuration and positioning of head flashing, in the form drawings showing integration with the existing brick veneer.
It ranges from difficult to impossible to directly integrate the existing WRB to a replacement window when access is limited.
Included in the document are configurations and placements of sill pan and jamb flashing. As always, the sill pan drains to the exterior and is sealed to the brick with an upturned interior leg, which serves as a back dam.
Field testing was conducted in 2019 on installations in three houses in Baton Rouge, La., and an FGIA/FMA/WDMA task group aims to issue a final version later in 2020.
Rich Rinka is technical manager, fenestration standards and U.S. industry affairs for the Fenestration and Glazing Industry Alliance (FGIA).
To view the laid-in version of this article in our digital edition, CLICK HERE.