Masonry Magazine July 1969 Page. 22
3/8"
3/8"
FULL SIZE DETAIL
SEE
DETAIL
BACK STOP
MATERIAL
RAKE 3/4" DEEP
PRIME
-SEALANT
INTERIOR FACE
OF WALL
-BACK STOP
RUBBER LIKE
MATERIAL KEY
3/8"
T
3/8"
1-1/2"
BACK STOP
SEALANT
EXTERIOR FACE
OF WALL
SEALANT
FULL SIZE DETAIL
DETAIL
TYPICAL CONTROL JOINT DETAILS
water penetration. Although most sheetmetal flashings can be soldered, lock-slip joints are required at intervals to permit thermal expansion. Plastic flashing materials which are joined by heat generally are pliable enough to permit some expansion and eliminate the need for expansion joints.
Wall Strength
Effect of flashing on wall strength depends upon mortar bond to both flashing and masonry. Through-wall flashing does not effect the compressive strength of a wall, but can reduce bending and shear strength. If placed directly upon a masonry unit without a mortar bed, the flexural strength of the wall at the point of the flashing is nil. However, through-wall flashing usually is located near the end of a wall span where bending forces are low. Also, when the flashing is laid in mortar, flexural strength is less affected.
Base Flashing and Damp Checks
Base flashing and damp checks are used at the base of walls and in piers. Base flashing diverts water entering above it to the outside of the wall; a damp check stops the upward capillary travel of water that has entered below the check.
Sill Flashing
Sill flashing is placed under and behind all sills, the ends extending beyond both sides of the opening and turning up at least 1" into the wall. In addition, sills should slope and project away from the wall so as to drain water away from the building wall. When the underside of a sill is not sloped it should have a drip notch, or the flashing should be extended and bent down to form a drip.
Head Flashing
Flashing should be placed over all openings except those completely protected by overhanging roofs. When steel lintels are used, flashing should be placed under and behind the exterior masonry unit with the outer edge of the flashing