Masonry Magazine December 1996 Page. 28
BELOW WALL OPENINGS AND ON SHELF ANGLES
FLASHING MEMBRANE IS
LAPPED OVER SILL PLATE
FLASHING
END DAM
FLAHING MEMBRANE IS
LAPPED OVER CMU
Enddam
FLASHING MEMBRANE
EXTENDED BEYOND
EXTERIOR FACE
OF BUILDING
INSULATION/GRIP
OPEN HEAD JOINT
WEEP HOLE
CONCRETE SLAB
STEP FLASHING
UP AND UNDER
FIRST COURSE
SHELF ANGLE SOFT JOINT
& SEALANT
Fig. 8 A
INSULATIONIGRIP
OPEN HEAD JOINT
WEEP HOLE,
CONCRETE SLAB
Fig. 8 B
Fig. 6
# Installation Over Wall Openings
The installation of the flashing for a sill condition is similar in both cavity and veneer wall systems. See Figure 6 & 7. An end dam is used once again to act as a moisture deterrent. The flashing collects any entrant water, and the end dam ensures that the water will be directed to the exterior. Weep holes are installed to provide an avenue of egress for the FLASHING MEMBRANE moisture. Ideally the end dam would be placed 6" to 8" beyond jamb lines above all wall openings.
# On Shelf Angles
EXTENDED BEYOND
EXTERIOR FACE
OF BUILDING
SELF ADHERING
FLASHING
PREFORMED
STAINLESS STEEL
OK COPPER
Shelf angles create a continuous horizontal break within the cavity, obstructing the vertical flow of moisture through the air space. If special attention is not given to the detailing and installation of shelf angles, moisture infiltration, efflorescence and brick spalling can occur. See Figure 8a. Due to the above factors, specifying the minimum amount of shelf angles will reduce the possibility of moisture damage.
If possible, an alternative method of design is to eliminate all shelf angles at all floor lines and bear the exterior wythe of masonry on the foundation as shown in Figure 8b. This eliminates potential problems inherent in shelf angle design. This wythe of masonry can support its own weight for several stories, while wall ties provide lateral stability.
FLASHING MEMBRANE IS
EXTENDED BEYOND THE
EDGE OF SHELF ANGLE
Another strategy is to bear the exterior wythe directly on the floor slab. See Figure 9. However, thermal bridging makes this type of system less energy efficient, and more reinforcement may be required in the slab to support the wall. Also, exposed slabs are susceptible to moisture infiltration, so special details must be developed to prevent wind driven rain from penetrating beneath the flashing and into the building. Flashing must be set in a continuous bed of mastic, or a self adhering flashing must be used to prevent the wind driven rain from entering beneath the flashing.
28 MASONRY-NOVEMBER/DECEMBER, 1996
Fig. 7
WEEPHOLE AT
24 OC
CONCRETE SLAB
EDGE
BRICK
HORIZONTAL
EXPANSION JOINT
AND SEALANT
HORIZONTAL JOINT
REINFORCEMENT
AT 10 O.C
# DISCLAIMER NOTICE
Fig. 9
This guide contains technical information on masonry wall systems. It provides some of the basic information required to properly design and detal these systems. This booklet does not cover all designs or conditions. The information presented illustrates only the principles that are involved.
The information contained in this booklet is based on the available data and experience of the technical staff of the Masonry Advisory Council. This information should be recognized as suggestions which, if followed with good judgement, should produce positive results.
Final decisions on the use of information, details and materials as discussed in this booklet are not within the purview of the Masonry Advisory Council, and must rest with the project designer, owner, or both.
Copyright 1996. Masonry Advisory Council. All rights reserved including rights of reproduction and use in any form or by means, including the making of copies by any photo process, or by any electronic or mechanical device, printed, written, or oral, or recording for sound or visual reproduction or for use in any knowledge or retrieval system or device. unless permission in writing is obtained from the copyright proprietors