Window and Door Installation
Home Builder’s Guide to Coastal Construction
FEMA 499/June 2005
Technical Fact Sheet No. 22
Purpose: To provide flashing detail concepts for window and door openings that:
--give adequate resistance to water intrusion in coastal environs,
--do not depend solely on sealants,
--are integral with secondary weather barriers (i.e., housewrap or building
paper – see Fact Sheet No. 23), and
--are adequately attached to the wall.
Water intrusion around window and door openings can cause dry rot and fastener
corrosion that weaken the window or door frame or the wall itself, and lead to
water damage to interior finishes, mold growth, and preventable building damage
during coastal storms. Proper flashing sequence must be coordinated across
responsibilities sometimes divided between two or more trade activities (e.g.,
weather barrier, window, and siding installation).
To combat wind-driven rain penetration and high wind pressures, window and door
frames must be adequately attached to walls and they must be adequately
integrated with the wall’s moisture barrier system (see Fact Sheet No. 9).
ASTM E 2112
Detailed information about window and door installation is provided in the
American Society for Testing and Materials (ASTM) standard ASTM E 2112, a
comprehensive installation guide intended for use in training instructors who in
turn train the mechanics who actually perform window and door installation. The
standard concentrates on detailing and installation procedures that are aimed at
minimizing water infiltration.
The standard includes a variety of window and door details. The designer should
select the details deemed appropriate and modify them if necessary to meet local
weather conditions, and the installer should execute the selected details as
specified in the standard or as modified by the designer.
Section 1.5 states that if the manufacturer’s instructions conflict with E 2112,
the manufacturer’s instructions shall prevail. However, because a manufacturer’s
instructions may be inferior to the guidance provided in the standard, any
conflict between the manufacturer’s requirements and the standard or contract
documents should be discussed among and resolved by the manufacturer, designer,
Pan flashings: Windows that do not have nailing flanges, and doors, are
typically installed over a pan flashing (see Figure 1). Section 5.16 of ASTM E
2112 discusses pan flashings and refers to Annex 3 for minimum heights of the
end dam and rear leg. Annex 3 shows a maximum end dam height of 2 inches, which
is too low for areas prone to very high winds (i.e., wind speed greater than 110
mph). Where the wind speed is greater than 110 mph, the end dam should be 3 - 4
inches high (the higher the wind speed, the higher the dam). (Note: Annex 3 says
that “high rain and wind are usually not simultaneous.” However, this statement
is untrue for coastal storms, in which extremely high amounts of rain often
accompany very high winds.)
Figure 1. pan flashing.
Although not discussed in ASTM E 2112, for installations that require an exposed
sealant joint, installation of a removable stop (see Figure 2) is recommended to
protect the sealant from direct exposure to the weather and reduce the wind-
driven rain demand on the sealant.
Figure 2: protection of sealant with a stop.
Exterior Insulation Finishing Systems (EIFS): Although not discussed in ASTM E
2112, when a window or door assembly is installed in an EIFS wall assembly,
sealant between the window or door frame and the EIFS should be applied to the
EIFS base coat. After sealant application, the top coat is then applied. (The
top coat is somewhat porous; if sealant is applied to it, water can migrate
between the top and base coats and escape past the sealant.)
Frame anchoring: Window and door frames should be anchored to the wall with the
type and number of fasteners specified by the designer.
Shutters: If shutters are installed, they should be anchored to the wall, rather
than the window or door frame (see Figure 3).
Weatherstripping: E 2112 does not address door weatherstripping. However,
weatherstripping is necessary to avoid wind-driven rain penetration. A variety
of weatherstripping products are available as shown in Figures 4 through 9.
Figure 3: Hurricane Georges in Puerto Rico. The window lying on the ground was
protected by a shutter. However, the shutter was attached to the window frame.
The window frame fasteners were over-stressed and the entire assembly failed.
Attachment of the shutter directly to the wall framing is a more reliable
method of attachment.
Figure 4: drip at door head and drip with hook at head.
Figure 5: door shoe with drip and vinyl seal.
Figure 6: neoprene door bottom sweep.
Figure 7: automatic door bottom.
Figure 8: thresholds
Figure 9: adjustable jamb/head weatherstripping.
Note: Set the threshold in butyl sealant. If a drain pan exists underneath the
threshold, weep holes must not be blocked with sealant or debris.
American Society for Testing and Materials. ASTM E 2112, Standard Practice for
Installation of Exterior Windows, Doors and Skylights. (www.astm.org)