Volume 13, Issue 7 - September 2012

AAMA Analysis

Preparing for The Worst
Performing Installations in Hurricane Zones
by Ken Brenden
kbrenden@aamanet.org

For doors and windows located in hurricane-prone coastal areas, there are three key considerations: structural resistance to high wind pressures, resistance to impact from wind-borne debris and water penetration from wind-driven torrential rains.

While doors and windows can be configured to stand up well to these onslaughts, even the strongest, tightest and most impervious product will not deliver the intended protection if the quality of its installation does not equally address the extreme conditions for which it was designed.

So, as construction and hurricane seasons begin to overlap, we are reminded of two industry standards that address exactly this concern for doors and windows installed with mounting flanges intended for use in wood frame construction (the most common installation configuration).

Hurricane-resistant installation must include the appropriate selection and use of anchoring devices, installation accessories, flashing and sealants.

Assuming structural integrity, uncontrolled water penetration has been cited as a major failure mode for door and window installations exposed to hurricane conditions. To address this concern, the mounting flange must join together with the exterior facing material, sheathing and the water-resistive barrier (WRB) to form a unified, fully integrated “drainage plane.” Therefore, the ultimate solution for hurricane water penetration lies in a robust integration of the door or window with the drainage plane.

Installation Basics: ASTM E2112
ASTM E2112 forms the foundation for installation methodology in mild climates, such as that experienced in the western U.S., and is in fact the basis for AAMA’s InstallationMasters™ installer training and certification course.

AAMA 2400, Standard Practice for Installation of Windows with a Mounting Flange in Open Stud Frame Construction for Low Wind/Water Exposure, an extension of ASTM E2112, covers the installation of new windows with integral mounting flanges or fins in a typical new construction stud wall. (AAMA 2410, Standard Practice for Installation of Windows with an Exterior Flush Fin Over an Existing Window Frame provides similar guidelines for the installation of replacement windows.)

But hurricane-resistant installation must take the basic methods outlined in these standards and improve upon them. In response to the Florida Building Commission’s 2004 request for more robust installation practices in hurricane zones, AAMA joined forces with the Window and Door Manufacturers Association (WDMA) and the Fenestration Manufacturers Association (FMA), to develop enhanced guidelines for the specific wall types typically found in the coastal southeast region.

FMA/AAMA 100
The recently updated FMA/AAMA 100, Standard Practice for the Installation of Windows with Flanges or Mounting Fins in Wood Frame Construction debuted in 2007. It builds on both ASTM E2112 and AAMA 2400/2410 by specifically addressing low-rise buildings with a membrane/drainage system that are subject to extreme wind/water exposure. It offers the option to use 4-inch wide self-adhering flashing or 9-inch wide mechanically attached flashing at the exterior jambs and head. The installation methods specified in FMA/AAMA 100 have been tested for water penetration per ASTM E547 or E331 at a test pressure of up to 575 Pa (12 psf), equivalent to the force exerted by a 69-mph wind.

FMA/AAMA/WDMA 300
FMA/AAMA/WDMA 300, Standard Practice for the Installation of Exterior Doors in Wood Frame Construction for Extreme Wind/ Water Exposure, also designed to align with ASTM E2112 and AAMA 2400/2410, is comparable to FMA/AAMA 100, except that it deals with doors. It addresses three scenarios for integrating side-hinged or sliding doors with a membrane drainage plane: doors with mounting flanges, doors with exterior casing/brick molding and non-flanged box frame units. It covers various sill conditions, including wood frame and slab on grade and sill conditions that terminate below the membrane drainage wall system.

Ken Brenden serves as technical services manager for the American Architectural Manufacturers Association in Schaumburg, Ill.


DWM

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