Masonry Magazine February 1993 Page. 55
CMU
1 to 2 gap
preformed
joint
-4" block
Granular
C
1'-0"
min.
Fiashing
Membrane
flashing
Open head joint
or cotton wicks
Granular
fill
Joint
sealant
Backer Compressible material
rod or void
Metal
flashing
Concrete wall,
grade beam, or
block
(a) 8" wall
FLASHING at a lintel or shelf angle (left illustration). Flashing at foundation (right).
Masonry Flashings-A
Blessing or A Curse?
Investigation reveals a lack of understanding by both designers and contractors as to the purpose of flashing.
By JAKE RIBAR
Principal Masonry Evaluation
Engineer, Construction Technology
Laboratories, Inc., Skokie, Illinois
MODERN MASONRY is thinner than its predecessors. It's often designed as a rain screen with cavities and flashings designed to expel water. Walls with properly designed and installed flashings provide weather resistant masonry construction, increased longevity and mimize maintenance. Investigation of masonry problems clearly reveals a lack of understanding by both designers and contractors as to the purpose of flashing. Properly installed flashings perform several functions necessary for satisfactory performance of masonry.
They create a slippage plane to accommodate differential movements between the masonry and the foundation.
They provide a path for water to be expelled from the masonry.
They prevent rising damp.
Flashing should be installed at the base of a masonry wall at finished grade, at all shelf angles and steel lintels, and where there is a change of materials in the horizontal plane (such as a change from a concrete masonry wall to a brick masonry wall).
Dedicate Ontario
Training Centre
APPRENTICE at left is one of some 44 new apprentices to go through the Ontario Masonry Training Centre's 42 week trowel trades training session during 1992. Each 40 hour week of training consists of 7 hours of technical presentations and 33 hours of practical hands-on training. The Centre became an attraction to visiting delegations from Australia, Japan and Russia, Provincial Association and American representatives last October to share in the celebration of the Centre's achievements at the official opening and dedication.
MASONRY JANUARY/FEBRUARY, 1993 55