pioneer courthouse square waterproofing evaluation

Transcription

PIONEER COURTHOUSE SQUARE
Professional Roof Consultants, Inc.
1108 NE Grand Avenue Suite 300
Portland, OR 97214
Voice: 503 280-8759
Fax: 503 280-8866
WATERPROOFING
EVALUATION
ProfessionalRoofConsultants.com
A SURVEY AND EVALUATION OF EXISTING
WATERPROOFING SYSTEMS AND WATER INTRUSION AT
PIONEER COURTHOUSE SQUARE
PRESENTED TO:
PORTLAND PARKS & RECREATION
APRIL 10, 2006
PROJECT # R2523.03
TABLE OF CONTENTS
o 1.
INTRODUCTION
o 2.
EXISTING CONDITIONS & FINDINGS
o 3.
CONCLUSIONS
o 4.
SUMMARY
o 5.
PLAN DRAWING
I NTRODUCTION
1.
1.
Introduction
In March of 2006, Portland Parks & Recreation retained Professional Roof Consultants, Inc. for the purpose of
performing a survey and evaluation of existing waterproofing systems which cover the structural concrete slab
over occupied spaces of the Pioneer Courthouse Square, located at SW Broadway and Yamhill in downtown
Portland, Oregon. The survey was conducted during the early portion of March, 2006, with the research and
report preparation prepared shortly after the initial survey work was completed.
Pioneer Courthouse Square, located in the heart of downtown Portland, was originally constructed / completed
in 1984. The one-block public space appears to be a predominantly uncovered outdoor gathering area;
however, the square is inconspicuously comprised of occupied space at the south and west sides of the block.
These spaces are the focus of this study, as they are dependant upon waterproofing systems to prevent
moisture from migrating into the finished public spaces below.
It is understood that water leaks have been observed at certain locations within the lower-level spaces, with reoccurring leaks becoming quite common, leading some to believe that the Square has been, and continues to
be, an expensive piece of property to maintain. This study was initiated to assist the City of Portland in
determining what actions are necessary to control leaks in the immediate future, as well as long term, with
regard to the waterproofing membrane over occupied spaces, and the skylight systems at the West side of the
Square.
This report serves several purposes, and a number of tasks were performed in order to present the desired
results. Primary tasks that were accomplished in order to present the required information include the
following:
1.
Investigate re-occurring leaks where moisture intrusion has been documented, including:
a.
b.
c.
d.
e.
2.
Various leaks associated with the
Starbucks east patio.
Leaks that exist within and around the
glass block “skylight” assemblies.
Back storage / hallway area at the west
side of the block.
Water intrusion located at the south
side of the block at inner offices,
located under the stairs and ramp.
Determine if short-term repairs can be
effectively implemented.
Evaluate the waterproofing system:
a.
b.
c.
d.
e.
Determine the type and condition of the
existing waterproofing system.
Determine probable life expectancy.
Establish where repairs can be
implemented in an effort to defer major
expenditures.
Establish a repair / replacement scope
of work.
Estimate cost impacts for the repair
and replacement scopes.
Pioneer Courthouse Square
Waterproofing Evaluation
1. Introduction
Page 1 of 2
Information presented within this report has been divided into several different sections. The following is a
brief summary description of what can be found within each section of this report.
1.
INTRODUCTION
This section, which describes the report outline, tasks and procedures associated with the retrieval of
information and assembly of the report, identifies referenced standards, and outlines the ultimate goals of the
evaluation and survey.
2.
EXISTING CONDITIONS
This section identifies individual components, and describes the existing conditions observed during the site
visits, with the findings determined through technical investigations. Photographic documentation is included
within this section, along with various graphic representations of the systems that cover the Square.
3.
CONCLUSIONS
A summary of the conditions found and conclusions drawn from each part of this evaluation, along with
summarized recommendations and graphic representations.
4.
SUMMARY
An abbreviated outline of recommendations for short and long-term actions for the Square.
5.
PLAN DRAWING
A scaled drawing of the plan view of Pioneer Courthouse Square.
Research for this evaluation and survey was limited to interviews with contractors, along with a review of a
limited amount of information provided by Portland Parks and Recreation personnel and Pioneer Courthouse
Square personnel. Actual documentation that has been reviewed includes:
9 Letter Report: “Pioneer Courthouse Square”, dated April 28, 2004 – Douglas W. Sinay, Inc.
Waterproofing & Exterior Façade Restoration.
9 Skylight Proposal / Order and Shop Drawing: Circle Redmont Inc. – Glass Block & Concrete Deck
Shop Drawing; dated 5/12/93, and accompanying Proposal / Order form with description.
9 Drawings: Pioneer Courthouse Square site plans – Hardscape Features (Sheet S1), Potable Water
(Sheet S2), and Utilities (Sheet S3) – submitted by Portland Parks & Recreation.
9 Correspondence: Various correspondence and interviews with Portland Parks and Recreation,
Pioneer Courthouse Square personnel, and D&R Masonry (contractor recently retained for repairs at
the Square).
Reference material used for research and ascertaining design criteria for this evaluation includes the following:
¾
¾
¾
¾
NRCA National Roofing Contractor’s Association (NRCA); The NRCA Roofing and Waterproofing
Manual - Fifth Edition.
Sheet Metal and Air Conditioning Contractors National Association (SMACNA); SMACNA
Architectural Sheet Metal Manual - Fifth Edition.
Roof Consultants Institute (RCI); Basic and Advanced Roof Consulting Manuals.
International Building Code - 2003 Edition, as amended and adopted by the State of Oregon.
1. Introduction
Page 2 of 2
E XISTING C ONDITIONS & F INDINGS
2.
2.
Existing Conditions & Findings
A waterproofing system was used to cover occupied spaces of Pioneer Courthouse Square during original
construction. The general area of the occupied, or interior spaces at the Square, is indicated diagrammatically
as the shaded area on the illustration below. The evaluation of the waterproofing system at Pioneer
Courthouse Square involved several tasks which were performed on March 6 and 7, 2006, including invasive
investigation of the system by removing layers of the existing brick pavers and other underlying materials until
the waterproofing system was visible. The invasive investigation locations, or Test Areas, are indicated below,
along with a general indication of water intrusion locations.
This section documents conditions found at each Test Area, along with results of isolated water testing and
detailed inspections of the construction of the Square from both above and below interior spaces.
LEGEND
AREA OF PREVIOUS OR CURRENT
LEAK LOCATION
INVASIVE INVESTIGATION LOCATION
WHERE SYSTEM WAS INSPECTED
INDICATES MEMBRANE TIE-OFF AREA
FROM PREVIOUS REPAIR
TIE-OFF AREA AT PATIO INFILL AND
MODIFICATION
#2
#1
TROUGH DRAIN
AT RAMP, TYP.
#3
LOCATIONS WHERE CRACKED /
FRACTURED BRICKS EXIST
2. Existing Conditions & Findings
Page 1 of 17
INVASIVE INVESTIGATIONS
Three locations were selected and prepared for isolated demolition and testing. D&R Masonry Restoration,
Inc. was retained by PRC for the purpose of performing all demolition and re-building processes at locations
as directed by PRC. Removal of construction materials at each test location began on March 6, 2006, and
concluded on March 7, 2006.
Test Area #1
This test area was selected due to it’s proximity to past leaks around one of the flush skylights, and to aid in
determining whether or not past leaks are occurring due to failing sealant systems at skylights and / or failing
waterproofing systems below the level of the brick pavers.
System Assembly: Originally installed in 1984,
with repairs / modifications performed in 1993
and within last 2 years. Removal of the
components revealed that the assembly consists
of mortared brick pavers (1½” x 3½” x 7½”
straight edge, fired clay brick pavers – believed
to be wire cut), set in a 2” thick layer of “drypack” setting bed which is reinforced with 2”
square stainless steel wire mesh reinforcing.
The paver assembly has been installed over a
loose-laid asphaltic (actually pitch-based)
protection board layer, installed over a fluid
applied, modified polyurethane membrane
applied directly to the structural concrete deck.
The membrane was measured at approximately
40 – 45 mils (0.045-inch) thick; considerably less
than a standard 60-mil installation.
BRICK PAVERS
“DRY-PACK”
SETTING BED
WIRE MESH
REINFORCING
PROTECTION
BOARD
WATERPROOFING
MEMBRANE
STRUCTURAL
CONCRETE DECK
Figure 1 – Typical Waterproofing / Paver Assembly
Test Area #1 – Observations and Findings
1.
This is an area where a tie-in occurred when the skylight units were replaced in 1993. The tie-in
occurs approximately 12” beyond the perimeter of the precast concrete skylight frame, with a newer
membrane installed directly over the original membrane.
2.
The tie-in area was found to exhibit delamination between the newer membrane and the older
membrane. The inadequate bond of the materials has allowed moisture to enter the system at
various locations; however, the delamination does not appear to be the main source of water intrusion
when leaks occur at this location.
3.
The waterproofing membrane used to repair the areas around the perimeter of the skylights is similar
to the original waterproofing membrane, and is believed to be Tremco TREMproof 250 GC.
4.
The original membrane that was found to be exposed at the test location is blistered and delaminated
from the structural concrete deck. Moisture exists under the membrane, which is probably due to past
leaks around the skylights, but could also be due to the increased permeability of the membrane (due
to minimal thickness and general deterioration due to aging).
5.
The blisters and bubbles that were observed within the original membrane are full of water. Where
material was opened and removed, the concrete substrate was found to be wet.
6.
In general, the existing (original) waterproofing membrane, which is now approximately 23 years old,
was found to be at or near failure at this particular location.
Page 2 of 17
TEST AREA #1 – PHOTO RECORD
1.01
1.02
Photo showing process of brick paver removal,
exposing the “dry-pack” setting bed.
1.03
Removal of the setting bed, exposing wire mesh
reinforcing.
1.04
Waterproofing membrane exposed below the setting
bed.
1.05
View of exposed waterproofing showing condition of
membrane and edge of tie-in at skylight repair.
1.06
One of several blisters which contained moisture.
Membrane is relatively thin and is disbonding.
Location where repair membrane was installed over
original membrane. Disbonding is occurring.
Page 3 of 17
1.07
1.08
Knobs are consequence of setting in drainage mat
over liquid membrane which had not fully cured.
1.09
Overall view of surface of waterproofing. Blisters,
pinholes, and disbonded materials were observed.
1.10
Photo illustrating how underlying moisture migrates
across waterproofing membrane at deck level.
1.11
View of uphill side of test area showing water /
drainage beneath the protection board.
1.12
Area was cleaned after initial inspection. Existing
membrane was cleaned, dried, and prepped.
Photo showing final repair prior to installation of new
setting bed and brick pavers.
Page 4 of 17
Test Area #2
This test area is located directly adjacent to one of the trellis columns; one which has been caulked at the base
of the escutcheon in an attempt to resolve water infiltration. The location is also adjacent to the west corner of
the south flush skylight. This location was selected to determine the existing condition of one of the trellis
column supports, to determine particular detailing at the base of the column; and to determine if caulking the
base of the escutcheon is recommended. An attempt to view the existing membrane at this location will also
verify typical conditions.
System Assembly: Originally installed in 1984, with repairs / modifications performed in 1993, and also
within last 2 years. Removal of the components revealed that the assembly is similar to the assembly at Test
Area #1, consisting of mortared brick pavers (1½” x 3½” x 7½” straight edge, fired clay brick pavers – believed
to be wire cut), set in a 2” thick layer of “dry-pack” setting bed which is reinforced with 2” square stainless steel
wire mesh reinforcing.
The paver assembly has been installed over a loose-laid drainage mat / protection layer (composite drainage
product consisting of three-dimensional "dimple" type polyethylene core with a non-woven, needle punched
filter fabric), installed over a fluid applied, modified polyurethane membrane (repair layer) applied over the
original membrane, applied directly to the structural concrete deck.
1.
Like Test Area #1, this is an area where a tie-in occurred when the skylight units were replaced in
1993. The tie-in occurs beyond the perimeter of the precast concrete skylight frame, with a newer
membrane installed directly over the original membrane. In this case, the tie-in wrapped around the
base of the trellis column.
2.
The tie-in area was not visible at this location; it appears to extend beyond the area that was opened
up for this test area.
3.
The bronze escutcheon that was removed around the base of the trellis column structure was caulked
to the brick paver assembly prior to removal. The caulking is believed to have been installed in an
attempt to prevent water from entering the base of the column when leaks were occurring in the past
(which were found to be a result of failing skylights).
4.
Close examination of the base of the trellis column revealed that water can migrate from the top of the
column (via joints and gaps in the bronze column cover and ornamentation), leading to the base
structure of the column which has been caulked to the brick pavers. Caulking of the joint at the base
of the column does not prevent water from coming into contact with the trellis base detail.
5.
The trellis base structure has a flexible bellows attached to a curb which exists between the four 1”
square rods which form the frame of the column. The bellows is covered with waterproofing
membrane which extends down over the sides of the curb, over the threaded rods and base plate
assembly, and down over a raised (2”) pedestal (dry-pack) under the base plate. It is unknown as to
why the bellows has been installed at this location, but may be acting as a dome over a void in the
curb / trellis base. The waterproofing at the trellis base appears to be intact and watertight.
6.
A void in the membrane was found at one of the corners of the brass base plate which supports the
trellis column structure. While this may not be a source of direct water intrusion into the building
structure, it is a possible weak point in the detailing of the column base.
7.
The nature of the column base detail promotes complicated detailing. The fact that so many
penetrations and possible movement exist at a critical location allows the possibility of failure.
8.
The repair membrane that was installed over the original membrane appeared to have a somewhat
adequate bond where exposed to view, and is in relatively good condition.
Page 5 of 17
2.01
2.02
View of base of trellis column after one half of
escutcheon was removed. Note caulking at base.
2.03
Removal of brick pavers and setting bed at column
base, being careful not to damage flashing detail.
2.04
Photo of condition of trellis column base after removal
of paver assembly. Drainage mat was left in place.
2.05
Location where small section of waterproofing is
delaminated from base plate; not necessarily a leak.
2.06
View looking up into column from base. Water stains
indicate that moisture enters the column from above,
which is expected, and supports the recommendation
to leave the column bases free of caulking.
Side view of column base showing bellows detail over
base plate, with waterproofing membrane applied
liberally over entire assembly.
Page 6 of 17
2.07
2.08
Opposite side of column base showing waterproofing
applied over bellows, base plate bolts and brass rods.
2.09
Overall view of test area looking south. This detail
has numerous potential points of water entry.
2.10
Photo taken during cleaning, drying, and prepping of
the area prior to installation of new waterproofing.
Test area after installation of new waterproofing
membrane, prior to installation of brick pavers.
Page 7 of 17
Test Area #3
This test was performed at a location on the sloping ramp of the large amphitheatre steps, located adjacent to
a trench drain at the south side of the radius. At the interior space adjacent to this location, a re-occurring leak
exists and is currently active. This location was chosen to identify the general condition of the membrane; to
verify connection into the trench drain, and to locate any defect in the membrane or structure which may be
contributing to water intrusion at this location.
System Assembly: Originally installed in 1984, this system is identical to the sequence and type of materials
as identified within Test Area #1. Repairs to the membrane have not been implemented at this location;
however, sealant and mortar repairs have been applied to identified cracks within the joints of the brick pavers.
1.
The area was significantly larger than previous test areas in an effort to expose more membrane and
more detailing. Upon initial removal of the materials, the setting bed (dry-pack) was found to be
solidly intact, and removal of the material was allowing damage to occur to the existing original
membrane at the structural deck. After removal of the brick, it was determined that only a limited
amount of setting bed would be removed.
2.
Where exposed to view, the membrane was found to be in better condition than the upper areas of
the Square (Test Areas #1 and #2), and was found to be approximately 60 mils thick; the minimum
thickness desired for this type of membrane.
3.
There were no cracks or noticeable deficiencies observed within the setting bed below the brick
pavers. The cracks that are visible from the upper areas at the south side of the Square do not
appear to extend down to the ramp level.
4.
Where a small sample of the membrane was removed, the concrete structure appeared to be dry, with
no visible signs of excess membrane deterioration. Small blisters in the membrane were observed.
5.
In general, the existing (original) waterproofing membrane, which is now approximately 23 years old,
was found to be in fair condition, with no visible failures. The area is a small sample, and should not
be considered a sampling of the entire area. The membrane is most likely approaching the end of its
useful service life.
3.01
3.02
Photo showing initial demolition stages at Test Area
#3.
Test area after brick pavers were removed and top
surface of setting bed was partially removed.
Page 8 of 17
3.03
3.04
Location at uphill side of test area where the setting
bed and protection board were removed, and the
membrane exposed. The membrane was in fair
condition, with only minor blistering.
3.05
Downhill side of test area at termination at trench
drain. The drain assembly is a “dual level” assembly,
allowing drainage to occur at the paver surface and at
the level of the waterproofing membrane.
3.06
Photo taken after area was cleaned, dried, and
prepped prior to application of repair material.
Photo or test area after membrane repairs were
installed, and prior to brick paver replacement.
Page 9 of 17
WATER TESTING
Activities:
Application of progressive and isolated water testing at
several possible / suspect leak locations, including the
trough-style water features at the Starbucks East Patio,
and on the surface of the East Patio..
Water Testing – Observations and Findings:
1.
Upon arrival on site, the surface of the troughs, as well as the brick
pavers within the east patio, was relatively dry, with the most recent
rain occurring 24 hours earlier (morning of March 5, 2006). Water
drips were active within the interior of the storage / maintenance
room below the Starbucks Patio at several locations; however, drips
were rather slow and infrequent.
2.
Starting at the East Trough of the water feature, water was applied
by hose at the high end of the trough, and was allowed to flow down the trough into the drain at the
catch basin between the separate drainage troughs.
a. Water was applied at 10:30 am, and was allowed to run continuously at a rate that is estimated to
be approximately 15 gallons per minute.
b. At approximately 11:00 am, the hose was removed from the trough drain.
c. RESULT: No increase in water intrusion at the space directly below the trough drain.
3.
At the South Trough of the water feature, water was again applied by hose starting at the center point
of the trough, directing water toward the high point before allowing it to drain downhill. Water was
allowed to drain into the central catch basin.
b. At approximately 11:35 am, the hose was removed from the trough drain.
4.
At the East Patio, a water test was conducted at the drain and the surface of the patio. Water was
applied by hose starting at the low point of the deck (next to the drain), with the drain slightly plugged
to allow only a limited amount of water to drain.
b. At approximately 12:10 pm, the hose was removed from the trough drain.
5.
The history of each of the leaks within the maintenance / storage area beneath the east patio is such
that water intrusion is quite regular with significant volume. The amount of water that was applied to
each water test should have activated the existing leaks if in fact the water feature were the source of
these particular leaks.
6.
Based upon the results of the brief and isolated water test at the perimeter of the patio, water intrusion
is believed to be originating in the field of the patio at other suspect locations, including the trellis
column detail and the tie-in areas where structure was changed to accommodate the new patio
design.
Page 10 of 17
WATER TESTING
4.01
4.02
Photo showing east trough during application of water.
4.03
Closer view of point of water application at east
trough.
4.04
View of common catch basis / drain located between
the two water feature troughs.
View of catch basin / drain during test of south water
feature trough.
Page 11 of 17
4.05
4.06
Corner at patio where area drain exists, prior to water
test.
4.07
Application of water over surface of east patio.
4.08
Photo of area drain during water test; drain bowl was
submerged.
4.09
Overall view of area where water was applied over
surface of east patio.
4.10
View under deck at area drain where leaks are
apparent, but not due to sources included within water
test.
J-box / conduit which penetrates deck near outer edge
of patio. Ordinarily a frequent drip location, water
testing did not activate this leak area.
Page 12 of 17
SKYLIGHT SYSTEMS
Activities:
Observations
of
existing
conditions and review of
available information pertaining
to the flush skylight systems
located at the West side of the
Square.
Skylights – Observations and Findings:
1.
New skylights were installed in 199, with
the precast concrete frame and glass
assemblies manufactured by Circle
Redmont, and believed to have been
installed by Pioneer Waterproofing.
SEALANT
JOINT, TYP.
6”X6” GLASS
SKYLIGHT
BRICK PAVER
ASSEMBLY
PRECAST CONCRETE
SKYLIGHT FRAME
Figure 2 – Illustration of what is believed to be a typical section
through the edge of the skylight at the brick paver termination.
2.
Since 1993, repeated attempts have been made to maintain the skylights in watertight condition.
Since each individual 6”x6” glass skylight is caulked into position within the precast concrete frame,
the assembly is considered sealant dependant, and must be constantly monitored and repaired.
3.
Over the past two years, D&R Masonry Restoration has been retained by Portland Parks &
Recreation to re-caulk the skylights. Foot traffic and abuse (including the effects of high heels, small
radius wheels, chairs, tables, and general high-traffic public use) have damaged the traditionally
installed (backer rod and sealant) joints.
4.
The most recent repair that has been performed at the skylights occurred in February of this year
(2006), again by D & R Masonry. This repair cycle included a different approach in an effort to
combat the abuse that a traditional sealant joint cannot withstand. With the old sealant removed, the
void at the perimeter of each skylight was filled solid with a sealant manufactured by Pecora
(Dynatred). The sealant is a 2-part, chemically-curing elastomeric (polyurethane) sealant which has a
medium rated firmness. While a properly designed sealant joint would include a backer rod to allow
the sealant to stretch without breaking or disbonding, the application of this type of joint is intended to
simply fill the entire joint with a somewhat stable sealant that is resistant to puncture.
5.
The most recent repair, upon the last inspection at the Square, has performed without fault for
approximately 3 months. Inspections should continue to observe for material failure or disbonding
from the sides of the joint. Evidence of failure will quickly be realized by the presence of leaks within
the building.
6.
The very nature of this type of skylight system is sealant dependant. The two different materials
which make up the assemblies (precast concrete and glass) require a seal between the materials in
order to prevent water intrusion. It is believed that the use of harder sealants, or double (stacked)
joints, or even complete filling of the joint, will provide a longer seal; however, the skylight “is what it
is”, and there should be no expectation of long term success. The skylight is considered a highmaintenance detail, and can only be improved in relatively small increments.
Page 13 of 17
SKYLIGHTS
5.01
5.02
View of skylights shortly before most recent repair
cycle.
5.03
Photo showing flush termination of skylight assembly
at brick band termination.
5.04
View of underside of skylight at interior of building.
Each glass pane is individually sealed.
5.05
Closer view of one corner that experienced prolonged
water intrusion.
5.06
View of skylight assembly during examination of Test
Area #2. Sealant joints are susceptible to damage
from patron traffic and tables / chairs.
Photo taken during examination of Test Area #1,
showing proximity of sealant detail at perimeter of
concrete frame, as well as trellis column base detail.
Page 14 of 17
CRACKS – BRICK PAVERS AND CONCRETE STRUCTURE
Activities:
Observations of cracked brick pavers at the south side of the square, just uphill from the ramp
leak location.
Key Observations and Findings:
1.
For the purpose of discussion, there are two tiers of brick stairs that are located just above the radius
set of stairs at the south side of the large amphitheater. These two stairs raise the level of the brick
plaza from the mid level, which covers the unoccupied space that once used to be occupied by
Powell’s Books, to the upper main level of the west side of the plaza.
2.
Both corners of the brick stairs were observed as part of the process of looking for obvious defects or
damage which may be contributing to the ramp leak.
3.
Both stairs exhibited straight line fractures and cracking of the brick pavers – both horizontal and
vertical surfaces of the stairs.
4.
At both stair corners, the lowest soldier course of brick which forms the first stair was observed to be
separating away from the horizontally set bricks. The separation occurred for approximately 2-feet.
Past repairs are evident, as the void was filled with mortar, and in some locations, sealant.
5.
Observations of the cracks by D & R Masonry personnel who were present to install the most recent
repairs revealed that the cracks within the brick joints have increased in size.
6.
Cracks were discovered at the far south side of the Square, at the approximate midpoint of the block
where the 2nd tier of stairs terminates at a terra cotta column. Major damage to the brick pavers has
occurred at this location.
7.
Cracks extend from a point on the upper plaza, near the terra cotta column, in a straight line toward
the Rain Man statue.
8.
Cracks and fractures in the brick extend through the brick pavers, not just the masonry joints. This
could be an indication of structural movement beneath the setting bed of the paver assembly.
9.
A tour within the unoccupied space beneath this area of the Square revealed a cast in place concrete
structure with cast in place concrete beams that form the tiers of the stairs – no columns were utilized
at the stepped construction of the concrete beams.
10.
The cast in place concrete structure ties directly into a perimeter foundation that is partially formed
from the original stone hotel foundation.
11.
Observations of the concrete beams revealed hairline fractures, or cracks, which appeared to extend
all the way through the beams. Cracks were observed at either side of a beam intersection.
12.
There were no signs of active water leaks within this unoccupied space, or any signs of previous
leaks.
13.
The tour continued into adjacent rooms and hallways, including the SW corner where the theater
resides. No active leaks were observed at any of the remaining rooms.
Page 15 of 17
CRACKS - BRICK PAVERS AND CONCRETE STRUCTURE
6.01
6.02
1st tier of steps where cracked brick pavers exist.
6.03
Fractured bricks at vertical face of “soldier” course.
6.04
Cracked bricks at 2nd tier of steps.
6.05
View looking south across 2nd tier of steps.
6.06
Straight line cracking of brick pavers at upper level.
Closer view of cracked bricks at upper level.
Page 16 of 17
6.07
6.08
Damaged brick pavers at far south side of Square.
6.09
Underside of structure showing concrete beams.
6.10
Cracks observed at either side of intersecting beams.
Another intersection with hairline crack in beam.
Page 17 of 17
C ONCLUSIONS
3.
3.
Conclusions
CONDITION OF WATERPROOFING MEMBRANE:
The majority of occupied spaces at Pioneer Courthouse Square are covered with a waterproofing membrane
that was installed in 1983 / 84. The membrane is a modified polyurethane material which is typically applied in
fluid form and allowed to cure into a monolithic layer, bonded to the substrate in which it is applied to. The
membrane that was installed is typically applied at a rate to result in a minimum thickness of 60 mils (0.060inch thick); however, test areas revealed some thicknesses between 40 and 45 mils – far less than what is
considered acceptable. While this type of
membrane is a popular and relatively simple
BRICK PAVERS
material to install, it has a typical life expectancy
“DRY-PACK”
of 20 – 25 years, rarely extending to the 25 – 30
SETTING BED
year life span that is sometimes expected. The
WIRE MESH
membrane is currently 23 years old.
REINFORCING
PROTECTION
Conditions found during this investigation ranged
BOARD
depending on location; the membrane was found
WATERPROOFING
to be at a state of failure at the areas around the
MEMBRANE
flush skylights and the east patio, and is
considered on the fair side at the ramp location.
STRUCTURAL
CONCRETE DECK
It should be noted that moisture intrusion may be
occurring at locations that are not exhibiting
obvious interior staining or damage. Water
intrusion will occur through membrane failure,
Figure 1 – Typical Waterproofing / Paver Assembly - Existing
but moisture quantities may be so minute that
accumulations evaporate or dissipate as fast as
moisture penetrates, and concrete can actually absorb a significant amount of water. While this scenario does
not result in visible interior damage, it can be detrimental to the concrete structure itself if allowed to continue
over long periods of time.
Solution:
Ultimately, the existing waterproofing system is at or near failure, and will require
complete replacement within a 2 – 3 year period of time in order to prevent further and
more widespread water intrusion. Replacement will involve complete removal and
replacement of the overlying brick paver and setting bed assembly.
Impact:
High. A large portion of the Square will be required to close for an extended period of time
while the membrane and brick pavers are replaced. This type of project could extend over a
period of 5 to 6 months.
Priority:
High. Leaks have already occurred due to failed membrane, and will only continue to
escalate as more time goes by.
ASSESSMENT OF LEAKS:
The purpose of opening and studying Test Areas, along with performing water testing at isolated locations
throughout the Square, offers the opportunity to understand the behavior of the existing waterproofing
membrane and its associated detailing at penetrations and terminations. Leaks that have occurred over the
past years are increasing in intensity, and are contributing to interior damage and disruption, and quite
possibly minor structural damage. The following are conclusions for each particular leak location based on the
results of this survey:
3. Conclusions
Page 1 of 5
East Patio at Starbucks
In the summer of 2005, the east patio underwent
a significant modification in an attempt to create
a more accessible and open exterior gathering
place for Starbucks patrons. The original
construction of the Square at this location
incorporated a “split-level” patio, with the head of
the south parapet water feature located closer to
the pavilion structure. The 2005 remodel
involved removal of original brick pavers at the
lower patio level, and infill of this level using a
combination of layers of rigid insulation and a
new reinforced cast in place concrete slab. The
new slab was poured at an elevation which
would result in a flush alignment with the upper
patio substrate, creating one large patio.
In addition to elevating the lower patio, the head of the south parapet water feature (trough) was removed and
relocated closer to the stairs leading up to the patio, consequentially creating a wider and more accessible
entry to the patio from the adjacent public space. The existing waterproofing membrane was left intact where
brick pavers were not removed (around the moved water feature and at the south side of the east patio).
Where modifications had been performed, and the new substrate completed, a new waterproofing membrane
was installed (a fluid-applied membrane similar to the existing original membrane) and lapped over the existing
membrane approximately 12”, resulting in a tie-in condition. Detailing at these locations apparently included
new terminations at parapets and building interfaces, and re-flashing onto an existing trellis column.
The trellis column detail is suspect due to the nature of the column assembly, and the fact that it was not
removed and re-installed onto the surface of the new raised concrete slab. In addition to the column structure
itself, electrical conduits that are routed within the column also penetrate the deck. It is understood that, when
the new waterproofing system was installed, the column flashing utilized securement of sheet metal around
the base, with the membrane extending onto the sheet metal – ultimately creating a “pitch pan” detail within
the base of the column. While this works fine for the field of the membrane, it does not adequately control
water which may (and does) enter the column from locations above the slab level.
Leak Sources: Suspected sources include suspicion of faulty or deteriorating tie-ins where new membrane
was applied over original membrane and even deteriorating original membrane where the
membrane was not replaced. Failure of the membrane may be occurring where the cold joint
of the new concrete exists, which may have shrunk or even settled over time, causing the
membrane to bridge a joint that exceeds the physical capabilities of the membrane. The
trellis column detail is also highly suspect, and may be allowing water to enter through
electrical conduits.
Priority:
High. The quantity of water that is entering the space below the patio suggests that there are
a number of failures at this location, and the current rate of water intrusion is causing
significant damage. Repairs can be successfully applied, but must be coordinated with water
feature improvements which are currently being planned.
Solution:
Complete replacement of the existing waterproofing membrane at the entire area, including
extension of the system up onto parapet walls that support the water features. This system
must tie directly into the waterproofing system at the water features in order to provide
cohesive and long-term performance. Replacement should not be deferred at this location.
An isolated project, considered a repair, can be implemented prior to complete replacement
of the Square waterproofing system.
3. Conclusions
Page 2 of 5
Flush Skylights
The two flush mounted skylights located at the west
side of the Square are comprised of precast concrete
grids with 6”x6” inlaid glass lights. The assembly is
reliant upon sealant to maintain watertight status.
The skylights have a checkered history, with an
unknown number of repairs performed at each of the
two skylight units; the most recent occurring in
February of 2006.
While sealant dependant detailing can be feasible
and functional if properly installed, the pitfall to this
particular assembly is its location; flush mounted
through a sidewalk in proximity to a highly used public
space and frequently visited coffee store. The
sealant joints which prevent water from bypassing
each skylight are susceptible to damage and abuse
(in the form of puncture and tear); possible culprits
include aggressive shoe soles and high heels, small
radius wheels, table and chair legs, etc. Typical
sealant joints, which utilize a thin layer of sealant
applied over a backer rod, are easily damaged, thus
resulting in immediate water intrusion in a flush
assembly such as this.
The most recent repair steered away from a traditional joint, opting for a solid fill joint in hopes that it would
withstand the abuses that have repeatedly allowed previous failures. The sealant material was also upgraded
to a “harder” type of polyurethane. This approach may be well-served; so far no leaks have appeared since
February of 2006.
Leak Sources: Leaks that occur at the skylight locations are predominantly caused by failed sealant joints at
individual glass units, and at the sealant joint that joins the precast concrete unit to the brick
pavers. Past leaks have also occurred due to the minimal waterproofing detail where the
concrete structure opens to the inside of the space below.
Priority:
Low at its current state. Can become High Priority immediately, creating a reactive situation.
The location is isolated, with only a medium impact on adjacent spaces; repairs can be
performed easily and quickly (relatively), with little demolition.
Solution:
There are several methods that may provide extended sealant joint life, including application
of solid fill joints, double joints, use of pourable (low modulus, self-leveling) sealants
combined with single sealant joint, and application of more durable (high-modulus) sealant
materials.
Regardless of what approach is taken for sealing the skylights, they should always be
considered a high maintenance element of the Square, and will require regularly scheduled
maintenance and repair in order to prevent leakage. More often than not, considering the
amount of caulking (648 lights, each with 2-feet of caulking, equates to nearly 1,300 linear
feet of caulking, not including the perimeter and division joints of the precast frame!), the
repairs performed here will be a result of reactive actions, not proactive.
3. Conclusions
Page 3 of 5
West Side of Square – Back Hallway and Storage
Water intrusion at the fat west side of the Square predominantly occurs
along the termination of the structural concrete slab of the Square, and at
various locations just east of the edge of the structure. While no test
areas were created in this area (due to proximity of heavily traveled
public right-of-way), it is presumed that, knowing the condition of the
membrane at other locations, and the possibility of cracks and joints in
the concrete slab, the membrane is no longer adequately covering the
substrate.
Leaks that are experienced within this area beneath the Square are not
visible to the public, and are not considered a nuisance as such.
However, uncontrolled water migration and intrusion can no doubt be
contributing to deterioration of the steel reinforcing within the concrete
structure, and does create a slight hazard at a location where periodic
access is required. Maintaining a clean environment is this back area is
also an ongoing task due to re-occurring and prolonged leaks.
Leak Sources: Water intrusion is predominantly caused by the ultimate
failure of the waterproofing membrane in the field of the
slab, and especially at concrete cracks and joints. Other
suspect areas include penetrations through the
waterproofing (i.e. sidewalk lift) and the termination of
the slab at the historic hotel foundation.
Priority:
Medium at this point in time. Short term repairs are not
possible without major demolition. This area should not
be phased as the risk of failure at a tie-in is high.
Solution:
Correcting deficiencies in this area can only be achieved by complete removal and
replacement of the existing waterproofing system. This should not occur separate from the
remainder of the Square. Impact is high since it covers a public access right-of-way.
South Side of Square – Ramp
A reoccurring leak exists just uphill from the 2nd
trough drain on the ramp of the main Square
amphitheater steps. The leak results in a small
but consistent quantity of water that enters
through a hairline crack in the cast in place
concrete structure.
Examination of the
waterproofing system near this leak did not offer
enough evidence to conclude that general
deterioration of the membrane is the root of the
problem. However, an examination of the brick
paver stairs just uphill from the leak point of entry
revealed cracked and displaced brick pavers.
Cracks or fractures within the brick extend in
various patterns at the 1st and 2nd tier stairs which
lead from the lower level surface (over unoccupied
space – former Powell’s Book Store), up toward
the midpoint of the south side of the Square.
3. Conclusions
Page 4 of 5
The cracks and fractures that have been observed exhibit a pattern of what could quite possibly be considered
structural movement or settling. In addition to cracks found at the stair corners, further cracking was noted at
the far end of the 2nd tier of stairs (at the termination to the terra cotta column), along with a straight line and
series of fractures running from the column to the rain man statue. What is considered alarming is the fact that
brick pavers are continuously fractured in a relatively straight line – not just through mortar joints.
Observations were made at the unoccupied interior space at the SE portion of the Square; there were no signs
of water intrusion within the open space. A close look at the somewhat complex array of cast in place
concrete beams revealed hairline cracking on either side of several beam intersections.
Leak Sources: Some conclusions made at this area are considered speculative, and will require further
analysis to determine if the structure is contributing to membrane failure. If the structure
actually has settled, and small cracks have formed and extended through the slab at changes
in plane, it can be safe to assume that the membrane has been forced to move further that
designed, especially so after being in service for 23 years.
Water is entering the structure through a failure in the membrane that is presumed to
originate at a stair corner directly uphill from the point of entry. The shifting and cracking of
the brick offer clues that would indicate a crack has developed and allowed the membrane to
split. The failure is most likely occurring at the change in plane, or just downhill from that
point. A failure that occurs at a higher point would not allow water to travel as far as it has
traveled.
Priority:
High since the leak is occurring at a location which is soon to be occupied.
Solution:
The first step is to allow for a structural review of this area to determine if the cast in place
concrete structure has settled more than the anticipated amount of movement, or determine
the possibility of an episode of overloading of the structure (live load).
Temporary correction of the leak problem may be achieved by sealing and mortaring open
cracks and joints at the stair corners. This process would not address the failed membrane,
but would simply decrease the quantity of water that comes into contact with the membrane;
water which ultimately drains “downhill” passing over membrane defects that contribute to
water intrusion. This repair would have the least amount of impact on the Square, and could
be performed immediately with little demolition.
The only effective method to alleviate this leak area includes complete removal and
replacement of the waterproofing system, including removal and replacement of the overlying
brick paver assembly. This entire area will prove to be the most challenging and costly due to
the complex geometry and particular brick layout of the radius, tiered amphitheater.
3. Conclusions
Page 5 of 5
S UMMARY
4.
4.
Summary
A waterproofing system was installed over the occupied spaces of Pioneer Courthouse Square during original
construction of the Square in 1983 and 1984. A layer of brick pavers and a mortar setting bed with wire mesh
reinforcing was installed over the membrane for the final finish surface. Over the past decade (and even
longer in the case of the skylights), the Square has been plagued with a number of re-occurring leaks, with the
quantity of new leaks increasing in frequency. The membrane, which is now 23 years old, is generally at or
approaching failure, and must be replaced in the immediate future in order to prevent further water intrusion.
The Square has undergone a number of repairs and modifications over the years, including the modification of
the pavilion (into Starbucks Coffee), replacement of the flush skylights (1993), and the 2005 modification of the
east patio adjacent to Starbucks. Numerous sealant and waterproofing repairs to the skylights have been
attempted in this time span, as well as changes in design / materials at the water features. Each of the repairs
and modifications that have taken place have required some level of tie-in or modification to the underlying
waterproofing system; some with success, but many with minimal or short term success.
The most obvious water intrusion problems that have plagued the Square have occurred due to high
maintenance sealant dependant detailing, and modification, or tie-in, to the original waterproofing membrane.
Other problems are due to membrane failure caused by general deterioration and / or structural movement.
Regardless of the source, it should be understood that the overall integrity of the existing waterproofing system
covering the Square is in a state of disrepair, and short term and long term plans must be considered and
almost immediately implemented.
An important caveat: the lines of responsibility at Pioneer Courthouse Square (i.e. Parks & Recreation, Water
Bureau, Pioneer Courthouse Square, etc.) must be shared in order to properly sequence the installation of
systems for total success of all assemblies, elements, and features.
SHORT TERM RECOMMENDATIONS
Priority 1
East Patio of Starbucks
(Repair Location #1)
This area is the most severe with regard to damage to
the structure and interior spaces. While not visible to
the public (and resulting in a somewhat lesser priority
in some aspects), water intrusion can and will impact
the structure and mechanical / electrical components
of this space.
REPAIR LOCATION #1
The waterproofing membrane and overlying brick
paver assembly must be replaced as soon as
possible. Replacement will allow proper detailing to
occur where not previously achieved, and will allow
failing systems to be replaced with long-term
systems. This option could be installed in a manner
that would allow the major renovation of the Square to
be tied into this area with minimal impact; ultimately
resulting in a phased application of the overall
system. The impacted area should encompass the
entire east patio, as well as the narrow area along the
north side of the Starbucks pavilion.
Estimated Cost:
$42,000.00
4. Summary
Page 1 of 3
Priority 2
Cracks in Brick Pavers
This scope is considered only temporary until
complete replacement of the waterproofing system
can be achieved. In an effort to control moisture
migration under the brick paver assembly, all open
cracks and joints at the south area of the Square
(specifically the two tiers of stairs just above the
lower ramp trench drain) should be sealed with a
sanded sealant joint application.
Estimated Cost:
REPAIR LOCATION #2
$3,500.00
for
temporary
repairs, unknown quantity for
structural evaluation and
associated
recommended
repairs (if any).
The next step for this area would include a structural
evaluation and assessment in an effort to determine
if settling, movement, or overloading of the structure
has occurred at this particular location.
Priority 3
Skylights
Since the installation of the most recent repair at the
skylights (2 months ago), leaks associated with the
skylight sealant joints have subsided.
No
immediate repairs are required at the skylight joints,
but funds should be available to repair them on
short notice, as sealant details can fail if physically
damaged, or if the joint itself fails due to expansion
and contraction or other natural forces.
Estimated Cost:
REPAIR LOCATION #3
Allow emergency repair fund
of
$2,000.00
annually.
Allocate $12,000.00 for future
repairs when full rehabilitation
is implemented (scheduled
when the Square undergoes a
waterproofing Replacement
scope).
Note: It should be recognized that, even with a complete modification and replacement of the sealant joint
system, the skylights will remain a high maintenance element of the Square. Proper inspection and
maintenance of the sealant joints can help prevent leaks into interior spaces; however, the nature of a sealant
joint is that it may require replacement between 5 and 10 years in an ordinary installation; sometimes more
frequently if located in a highly abusive environment such as this. The only method of reducing the risk of a
sealant joint is to eliminate the skylights or install a raised skylight assembly, both of which present
disadvantages (no light if eliminated, and a “climbing” hazard if raised on an elevated platform of curb).
4. Summary
Page 2 of 3
LONG TERM RECOMMENDATION
The existing waterproofing system is expiring, and must be scheduled for replacement. Based upon existing
conditions found, the scheduled replacement date should occur within the next 2 years. The project would
be a significant undertaking, and would require partial closure of the Square for a period of up to 6 months. A
project that is properly designed and constructed could provide positive results for up to 40 years. A
replacement scope would include the following:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
Remove and store all planters, statues, and other items that sit atop the areas to receive new
materials.
Provide adequate safety barricades and protection around the area of work; make temporary
accommodations for access into Starbucks Coffee and other lower occupied spaces.
Brick patterns and placement must be inventoried and well-documented.
Custom bricks with engraved names must be identified and locations documented for reinstallation.
Remove existing brick pavers, mortar setting bed, and stainless steel wire mesh reinforcing.
Remove brick at vertical parapet walls in order to properly extend the new system up and into the
systems that exist at the water features and tops of parapets.
Granite veneer panels at the water features (including the fountain) must be removed where
waterproofing systems extend behind the panels.
Remove existing protection board to expose the waterproofing membrane.
Remove existing waterproofing membrane from the surface of the cast in place concrete
structure. It is anticipated that approximately half of the area would require more extreme
methods of removal, such as bead blasting or scarifying the surface. The existing water proofing
must be removed in its entirety, and the concrete substrate must be clean and free of any
contaminants that would prohibit proper adhesion of a new system.
All cracks in the concrete should be inspected and repaired as required to provide a suitable
substrate for the membrane, and to reinforce the structure if found to be defective.
Skylights must be removed and stored, and the perimeter curb detail revised with appropriate
water dams and flashings to prevent migratory moisture from entering the openings.
All penetrations must be adequately addressed and detailed for long-term performance.
Restore drains and replace deteriorated parts. All drains must be double drain style, allowing
drainage from the surface of the waterproofing and the surface of the brick pavers.
Install new reinforced waterproofing system over properly prepared concrete deck. Consider
high-build, hot rubberized asphalt type of assembly. Require 20-year warrantable system.
Inspect and test membrane prior to installation of overburden; include water testing.
Re-install skylights over new perimeter curb detail, and install new double sealant joint system at
all joints. Utilize high-modulus, self-leveling sealant for first layer, and low-modulus, traffic
bearing sealant (silicone or modified urethane) for finish joint.
Provide high density drainage course / protection board layer over completed membrane.
Provide mortar setting bed with stainless steel reinforcing mesh.
Provide new brick pavers set to match existing pattern and layout; provide sealant joints at all
control joint locations.
Re-build stairs and ramp with proper soldier courses and radiuses, incorporating sealant joints at
control joint locations.
Provide new engraved name bricks, set into previously “owned” locations.
Re-install granite veneer panels at all water features and reseal all joints.
Re-install all statues, planters, and other features that were required to be removed for the
project.
Estimated Cost:
Budget $940,000.00 for construction. Outside consulting fees for design, inspection, and
other services can range from between $40,000.00 and $75,000.00, depending on the
level of involvement requested and required.
4. Summary
Page 3 of 3
P LAN D RAWING
5.

pioneer courthouse square waterproofing evaluation

Transcription

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