Steve Strawn, chair of the AAMA Flashing Committee, reported on the status of code referencing of AAMA flashing standards and work of the FMA/AAMA/WDMA Installation Committee.
The 2018 residential code (IRC) (R609.1) says that windows and doors must be flashed per manufacturer’s written instructions, at a minimum complying with section R703.4. The latter now references AAMA 711 for self-adhering membrane flashing and AAMA 714 for fluid-applied membranes. It also specifies certain installation details, primarily per the manufacturer’s instructions. Mechanically applied flashing must comply with AAMA 712.
The FMA/AAMA/WDMA Installation Committee was formed in 2005 to address water penetration in residential construction subject to extreme exposure conditions and to forestall the tendency to blame fenestration for leaks that originate elsewhere. The result has been the following series of installation standards published between 2010 and 2012.
- FMA/AAMA 100 for windows with flanged mounting fins in wood frame walls presents three alternative methods to prevent water infiltration at the jamb and achieve correct “weather board” shingling with the sill flashing
- FMA/WDMA 200 and 250 concentrate on isolating the rough opening and deflect moisture to the drainage plane
- FMA/AAMA 200 for windows with frontal flanges (aluminum and vinyl) in surface barrier walls
- FMA/WDMA 250 for windows without frontal flanges (wood) in surface barrier walls
- FMA/AAMA/WDMA 300 for exterior doors with mounting fins in wood frame walls includes methods for mounting flange, exterior casing (brick mold) and box frame (non-flanged) attachment systems
- FMA/AAMA/WDMA 400 for doors with mounting fins for surface barrier walls describes the use of fluid applied flashing to isolate the rough opening
The most recent addition to the anthology, FMA/AAMA/WDMA 500-16, covers proper integration of exterior Foam Plastic Insulating Sheathing (FPIS) with windows. It describes four methods (A, B, C1 and C2) covering various configurations, each of which were tested for practicality and water intrusion efficacy.
Efforts continue to fine tune this application by developing standards for structural support of windows using a Rough Opening Extension Support Element (ROESE). The default composition of the ROESE is wood, although there is interest in utilizing alternative materials such as those that feature insulating value. The structural integrity of alternative ROESE materials, particularly for various window sizes/weights and anticipated exposure loads, is under study as an active DOE-funded program sponsored by Home Innovations Research Labs (HIRL).
The next major project will be to focus on replacement window installation methods. The joint committee formed a task group in 2013 to develop guidelines for pocket replacements into a wood frame or existing aluminum frame, and for full frame replacement with or without partial cladding removal. A replacement decision tree has been developed and six replacement scenarios have been defined based on three distinct water management strategies and depending on interior and exterior surface conditions.
For the future, the committee is considering whether regionally specific installation details are advisable, given the wide variation in climates, exposures and regional practices.