Flashing Installation Steel Frames - International Masonry Institute

TM
TECHNOLOGY BRIEF
MASONRY CONSTRUCTION GUIDE
June 2004
RESOURCE INFORMATION FROM THE INTERNATIONAL MASONRY INSTITUTE
Flashing Installation: Special Conditions
Masonry Wall with Structural Steel Frame
Section 2.7.4
Scope
This Technology Brief presents general
information on the installation of flashing.
The intent of this guide is to provide
instructional information on successfully
installing flashing at conditions encountered
in masonry walls with structural
steel frames. This guide does not
preclude flashing details presented on
architectural documents. This guide
addresses the installation of flexible and
semi-flexible flashing membranes and
does not address the installation of rigid
flashing materials.
Introduction
When structural steel frames are infilled
with concrete block and veneered with
masonry units, flashing installation can
get complicated. The system is essentially
a masonry cavity wall with a structural
steel frame support system. However,
standard cavity wall detailing is not adequate
for the conditions that occur with
the addition of the steel frame. Difficult
flashing conditions occur at steel columns
embedded in the concrete masonry.
Flashing installation is further complicated
at shelf angle and corner locations.
Steel tolerances are substantially greater
than masonry tolerances, so irregular
field conditions are to be expected at
the interface of the two materials. A complex
series of cuts and folds are required
to install flashing at these locations.
Additional time, effort, and skill are
required by the mason to produce
successful flashing installation.
Flashing Installation at
Intermediate Columns
Columns located between concrete
masonry infill panels create vertical
Figure 1
FLASHING AT COLUMN SET BACK FROM CAVITY

Figure 2
FLASHING AT COLUMN SET INTO CAVITY
from the wall cavity. The space in front
of the column can be infilled with concrete
masonry soaps. The flashing can
be terminated within the CMU infill by
cutting and folding its end over the CMU
soap and adhering it against the column
flange.
Figure 2 illustrates flashing installation
at a steel column that protrudes several
inches into the wall cavity. Prefabbreaks
in CMU coursing. Consequently,
termination of the flashing into the CMU
bed joint is disrupted at every column.
Special cuts, folds and prefabrication are
necessary to maintain flashing continuity.
Column shape and proximity will dictate
flashing installation methods.
Figure 1 illustrates flashing installation
at a steel column set back several inches
ricated or field formed components are
required to maintain flashing continuity.
Flashing dams must be installed adjacent
to the CMU where the column flange
protrudes into the cavity. If the flashing
dams are omitted, water that collects on
the flashing will be diverted towards the
column and possibly into the building.
Flashing continuity can be maintained by
cutting and folding a separate piece

Figure 3
FLASHING AT COLUMN SET FLUSH WITH CAVITY
of flashing and adhering it to the column
and adjacent flashing membrane.
Figure 3 illustrates flashing installation
at a steel column with the column web
positioned parallel to the wall cavity.
Columns set in this manner create a void
in the CMU backup, which makes flashing
placement difficult. Masonry units
should be set between the column
flanges to create a profile that approximates
that of the CMU infill. The flashing
can be terminated by lapping it over
the masonry units and adhering it to the
web of the column. Prefabricated or field
formed dams must be adhered to the
flashing within the column to prevent
water from flowing down the column
flanges and into the building.
Flashing Installation at
Corner Columns
Steel columns located at outer and inner
corners create particularly difficult
flashing conditions due to steel column
shape and its increased exposure to the
wall cavity. A complex series of cuts,
folds and field fabrications are required
to achieve successful flashing installation.

Figure 4
OUTER CORNER FLASHING AT WALL BASE
Figure 4 illustrates flashing installation
of an outer corner column located at the
wall base. The column web and flange
are completely exposed to the wall
cavity at the outer corner. This creates a
flashing surface with multiple juts and
returns. Several flashing dams must be
provided to accommodate the irregularities.
Attempting to extend, cut, and fold
a continuous piece of flashing around
the column can prove to be difficult.
Field fabricating pieces of flashing and
neatly wrapping them around the
column surface likely will produce
improved results.
Figure 5 illustrates flashing installation
of an outer corner column located at a
shelf angle. Flashing installation at this
location is unique because all surfaces of
the column are exposed to the wall
cavity. A complex series of cuts, folds and
flashing fabrication are required to
ensure flashing continuity. All flashing
ends should be terminated by adhering
them to steel surfaces. Attempting to
extend the flashing into the CMU wythe
above the steel beam is not practical and
is difficult, if not impossible, to achieve.

Figure 5
OUTER CORNER FLASHING AT SHELF ANGLE
Figure 6 illustrates flashing installation
of an inner corner column located at a
shelf angle. Flashing inner column corners
is not as complex as outer corners.
Flashing continuity can be maintained
by carefully cutting, folding and lapping
the flashing ends. A flashing dam is
required parallel to the column web to
divert any collected water away from the
column and back into the cavity.
Conclusion
Flashing masonry walls with structural
steel frames can be tedious and requires
additional time, effort, and skill by the
mason. Installation may be compromised
by the difference in construction tolerances
as steel tolerances are often greater
than those accepted in masonry. Field
conditions often demand adjustments
to be made to details shown on project
drawings. The intent of this guide is to
show solutions to common situations that
occur. It is not to preclude other solutions
put forth by the contractor or the
architect.

Figure 6
INNER CORNER FLASHING AT SHELF ANGLE
This document is intended for the use of industry professionals who are competent to evaluate the significance and
limitations of the information provided herein. This publication should not be used as the sole guide for masonry design and
construction, and IMI disclaims any and all legal responsibility for the consequences of applying the information.
© IMI 2004. All Rights Reserved.
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