Stucco Flashing Details -
Equally important is a kick-out flashing at the edge of the
eaves. This metal flashing is really the first line of defense,
because it catches any water coming off the roof and directs it
away from the wall surface (for kick-out detail, see
"Installing Water-Managed Synthetic Stucco," JLC 9/98).
As with all other flashing details, the building paper should
be layered properly so that water drains to the bottom of the
Horizontal stucco surfaces, such as balcony railings and pot
shelves at recessed windows, are especially prone to leaks
because they are fully exposed to the weather. Unless they are
carefully detailed, water from repeated soakings or ponding
will eventually penetrate the stucco base and finish coats and
wet the underlying framing. When the wood swells from this
extra moisture, it causes the stucco to crack, which leads to
more leaks, more swelling, and more cracks.
We always inspect the framing before flashing a horizontal
surface to make sure that it slopes 1/4 inch per foot -- more,
if possible -- so that water will drain freely. If the framing
is level or, worse, sloped back toward the building, we won't
touch it till the problem has been corrected.
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6. Leaks at parapets, pot shelves, and other
horizontal surfaces can cause framing lumber to swell
and crack the stucco. To promote drainage, the
horizontal framing must be adequately sloped and should
be fully flashed with a self-adhering membrane. The
stepped slab also serves to contain leaks.
On a properly sloped horizontal surface, we apply a layer of
Vycor adhered directly to the sheathing and extending down over
the edges to overlap any building paper coming up the sides
(Figure 6). If the surface is in front of a window, we run the
membrane under the bottom nailing flange and onto the sill
plate. Similarly, where the horizontal surface meets a wall, we
run the membrane up the wall where it will be overlapped by
building paper. As with all of our flashing, we're careful not
to tear or punch holes in the paper, and we make sure that the
paper is layered so that water will drain away from the
Use as few nails as possible on the horizontal surface, and
caulk or patch every rip, tear, or hole.
owns and operates
Prime Plastering in Norco, Calif. He has worked as a plasterer
for more than 30 years.