List of Unusual Problems
Hidden Persistent Leak in Fourth-story Walking
The Hamlet Condominiums
4149 F El Camino Way
Palo Alto CA 94306-4035
DECK COVERING FAILURE ANALYSIS
(All jobsite directions such as left or right, are with the
viewer facing the property from the street or in front of the front entrance.)
The fourth-story, texture-coat
protected deck area has leaked persistently since being constructed.
- Multiple attempts at repair have
- The structure was built ten years
The fourth-level deck above the third-story family
room of this condominium has experienced severe and continuous leaking since it was
constructed ten years ago. This deck with adjoining roofs and corridors has been
repaired over a dozen times by several different waterproofing repair firms since
construction but the leaking continued. Litigation was occurring. No
waterproofing company was able to stop the leaks.
The Simpson Company was called-in to examine the problem in 1998. Our preliminary
inspection revealed that the flexible deck system on this leisure-deck was installed over
an epoxy-sand mortar built-up to almost one-inch thick in a futile attempt to divert
standing water into two small deck drains to stop the leaking. Large cracks up to
one-eighth of an inch in diameter in this surfacing were obvious leaks, but we deduced
that the volume of water entering these cracks was insufficient to cause the ceiling
collapse that had proceeded our being engaged as consultants.
Furthermore, this deck surface itself was one of the
unsuccessful attempts at repair of the leaks. Therefore it was possible that the
previous deck surface, installed during construction, was not cracked before being
replaced. If this was so, then the leaking was occurring even before the current
deck surface cracked.
The Simpson Company decided to dismantle the roof
tiles, roof felt, roof flashings, deck surfacing, corridor surfacing, corridor-wall stucco
surface etc., peeling down until we felt that we discovered the culprit.
This deck has eight different areas of
varying construction detail of interest to this inspection:
- The overall field area of deck surface.
- The field area of the two attached corridors.
- The four-story, north-side, perimeter, 24-inch,
parapet wall flashing.
- The one-story (above landing), south side,
decorative, four-inch, parapet wall flashing.
- The 10/12-pitch, aggregate-tile, adjoining, roof
- The deck to corridor flashing.
- The corridor to wall flashing.
- The corridor to exterior wood flush-door flashing.
Details of Inspection Results:
- The overall field area, about 500 square feet, of
deck surface has large random cracks, which appear to be caused by expansion and
contraction of a deck coating installed over a ¾-inch non-reinforced epoxy-sand mortar
system. This aggregate has developed cracks up to 1/8-inch wide, which penetrate to
the plywood surface below allowing rainwater to contact this plywood.
- The field area of the two attached corridors,
replaced last year, is showing no visible damage at this time and was not opened for
- The four-story north side perimeter 24-inch parapet
wall flashing appears to suffer no visible damage and was not opened for inspection at
- The south side, four-inch parapet-wall flashing
appears to suffer no visible damage at this time. This purely decorative toe-wall
creates a needless water dam. This water dam caused major water pooling during the
1997/98 El Nino storms. The two small (shower drain) deck drains were inadequate to
relieve the water backup. This small-volume drainage situation can be relieved with
the simple addition of two four inch wide spillways into the two existing rain gutters
which contact the underside of the straight toe-wall at each end.
- The 10/12-pitched aggregate-tile adjoining roof
bottom eave flashing was improperly installed. This lower eave roof-deck plywood
ends at a level of 1.5-inches above the texture coated deck surface. The roof deck
"L" flashing has a 2.5-inch vertical rise, much lower than the 4-inch parapet
wall and yet higher than the adjoining 1.5-inch pitched roof-deck. This flashing
should have been an exaggerated "Z" shape with a vertical rise of 1.5-inches and
an additional angled run of 7.5-inches to create an effective total height of 6-inches.
A bottom roof-tile flashing using a 1-inch leg perpendicular to the sloped roof
deck supported the lowest roof tile course. This I-inch step was not provided with
weep holes or other drainage, creating an effective water dam. There was no outlet
from this water dam. The accumulating water from the tarpaper moisture barrier under
the aggregate tiles was forced to seep through the rake end of the flashing at the
adjoining corridor sidewall. This water formed a pool on the pitched plywood roof
deck i.5-inches above the texture-coated deck in the corner where the corridor intersected
the pitched tile roof. This triangular-shaped pool was created by the vertical
component of the deck flashing, the vertical component of the corridor deck flashing where
the rake of the pitched roof approached within 1.5-inches of the texture coated deck, and
the sloped plywood roof deck itself. The more or less constant water pooling in this
area engendered fungus damage to the plywood in addition to a constant leak into the
inside lower room. Drawing 2-D shows some detail of this flashing.
- The deck to corridor flashing was not opened for
inspection at this time.
- The corridor to wall flashing was not opened for
inspection at this time.
- The corridor to exterior wood flush-door flashing was
inadequate. This door appears to have had some wood cut off from the bottom and not
primed or painted. The corridor deck texture coated surface was raised to actually
contact the lower edge of this wood flush door, which normally should have been I-inch or
more above the deck surface. The more or less constant contact with a wet deck
surface during the rainy season has caused the door to bloom and delaminate at the bottom.
Wood fungus was engendered because of this. Termites were welcomed by this
easy access and the door area is now infested with both fungus and termites.
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Last updated on 28th May 2004.
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