List of Unusual Problems
The Moving Pipe,
which only leaked during strong wind.
Palo Alto Central Condominiums
153 California Avenue
Palo Alto CA USA
INSPECTION REPORT for Unit F101
(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.)
- In a condominium Association, a unit named Unit F101
and adjacent units and storage spaces had a severe continuous water leak from the outside
walls along the Northwest building exterior.
- This leak had existed since construction was
completed almost ten years previous.
- Repeated and constant attempts by many different
companies over several years failed to correct this problem.
- Unit F101 is on the ground level, above an
underground-parking garage, at the West end of Building 153. There is a stairway
attached to the exterior wall of F101 leading up to an exterior second level walkway with
stucco-covered safety railing balustrade used as the main entrance for second story units.
This walkway top surface is finished in 2-inch concrete over plywood decking and
wood framing and stucco covers the sides and bottom. All walls of the buildings,
stairways, walkways etc. are stuccoed.
- Prior attempts to repair the leaks had included
re-surfacing the stucco, replacing the aggregate stairway, re-surfacing the second level
- The consensus of the many companies attempting to fix
the leaking was that the problem was in the rain gutter-to-roof and/or the top wall
Incorrect repairs were requested
- SimpCo was asked to correct improper flashing where
the galvanized-steel rain gutter mounted against the stucco at roof level above the West
corner of the Northwest exterior wall. A downspout existed at this corner, mounted
upon the Northwest wall. The gutter had been improperly installed directly against
the wall sheathing before the stucco was installed. When the stucco was installed,
the installers ended the stucco below the rain gutter instead of installing stucco behind
it. Additionally, the gutter installers failed to seat and solder the gutter outlet
in a good competent manner and water readily escaped through the bottom of the gutter.
Water escaping from this leaky outlet was allowed to run directly behind the
SimpCo initiated a Forensic
- SimpCo conducted a Forensic Examination of the
outside and inside of the roof and walls of the top floor and the outside of all other
floors. Although the poor workmanship problems listed above were evident, SimpCo
staff knew that the amount of water leaking from this defective gutter outlet was grossly
insufficient to cause the massive amounts of water entering into the condominium.
SimpCo changed the repair
specifications and repaired the defect
- Rather than proceed with the repairs, SimpCo staff
opened several holes into the structure and the enclosed deck and stairway. SimpCo
staff inserted cameras designed to fit through small apertures into these examination
openings. On one test aperture into the walkway SimpCo staff discovered the entire
cause of the leaking problem and subsequently repaired it. SimpCo staff also repaired the
poor workmanship of the wall flashing and the defective rain gutter and downspout
conductor head installation.
Explanation and drawing of the defect
- The problem is shown in the attached drawing.
The 3x4-inch commercial-size galvanized steel downspout at the West end of the
Northwest wall led into a 3.25x4.25-inch galvanized steel nipple set into the concrete
surface of the walkway, an unusual arrangement. This 12-inch nipple lead into a
4-inch round cast iron sewer pipe that led horizontally inside of the walkway until it
could exit downward into the sewer lines fastened to the ceiling of the underground
- The nipple was 1-inch too short of joining the
downspout to the sewer pipe. This 12-inch nipple should have been 14.5-inches long.
The rain gutter downspout had no middle fasteners. When the wind blew hard,
the downspout deflected slightly. This slight downspout movement caused the nipple,
pivoted at the concrete walkway surface entrance, to swing its bottom end fully two-inches
in the opposite direction. When the nipple was in a swung-over position, it was no
longer over the sewer pipe opening and the 12-square inch volumetric area of exiting
rainwater water was dumped into the walkway interior space. The water then filled
the walkway like a bladder and soaked through the wall where the walkway was adjoined to
the building and into the inside living quarters.
It only leaked when the wind blew
- When there was no wind, all of the pipes hung plumb,
then 99% of the water entered the sewer pipe and there was no leaking! However, when
the wind blew during rain, the downspout shifted slightly causing the bottom of the nipple
to move sideways thereby aiming its water egress into the open plenum of the staircase
- Gene Simpson, an engineer with decades of
construction experience, holds a Masters Certificate in Concrete Repair. Mr. Simpson
will answer short questions regarding this article if you call him at SimpCo Corp., 650/
289-0006 or email via the SimpCo.com Website. As the Technical Operations VP at
SimpCo, Gene is in charge of Structural Forensic Analysis, concrete and post-tension
member repairs, assisting the Project Management staff with technical specifications and
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Last updated on 2nd June 2004.
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