|
It is an unfortunate
truth that most
stadiums leak at expansion joints. The responsibility for this dubious
track record lies with all parties involved. The rare exceptions--stadiums completed with watertight joints--are characterized by a process
that involves a shift in the traditional way the stakeholders relate and
execute their work.
OWNERS: Owners of
all structures live with problems. The top-two are leaks and HVAC
balance. Only leaks, however, come with the consequence of enraging
suite subscribers, players, owners, and vendors who occupy the finished
spaces beneath them.
When one considers that
less than 1% of a typical budget is spent on expansion joints and as much as
90% of post-tenancy problems with structures relates to water ingress, then
budget emphasis is clearly one place to begin addressing the problem.
For designers to properly do their jobs,
owners must be receptive to the recommendation of superior technologies
presented to them, and must be prepared to allocate additional resources to
the design contract to allow proper detailing of joints and their
relationships to other structural elements.
By spending slightly more than the average 1% of their
construction budget on waterproofing and by hiring designers entrusted with
the challenge of designing structures so they don’t leak, owners can expect
dry stadiums and lasting joint seals.
DESIGNERS:
When budget constraints force designers to simplify, it creates
circumstances in which stadiums are, by default, designed to leak.
Absence of the incorporation of a
number of essential design principles, failure to communicate expansion
joint design issues within the proper context, and the absence of proper
detailing in three dimensions, all contribute to expansion joint failure.
"Problems with expansion
joints often occur because there is often confusion as to who is responsible
for design of joints and choice of sealants and because DETAILED DESIGN IS
LEFT TOO LATE-- so that decisions already taken make it difficult to
execute a satisfactory joint" (CIRIA). The communication of movement issues between
structural engineers often lacks consideration of the performance
limitations of expansion-joint sealant technologies. The result is a
disconnect between movement theory and practical constraints of movement at
the as-built and sealed joint condition.
GENERAL CONTRACTOR:
Failure to emphasize expansion joints during construction is a significant
contributor to delays, cost overruns, and reworking that characterizes
preparation of joints to receive expansion joint systems. The
treatment of expansion joints must be emphasized throughout the construction
process. Communication of joint treatment by ALL trades must be
emphasized in all progress and coordination meetings if retrofit of joint
conditions is to be avoided. GC's need to change their thinking about
joints. The general attitude is that they are a necessary nuisance.
Joint are by in large swept under the rug until towards the end of the job.
Instead, expansion joints must be considered a critical path item. All
workers must respect, provide proper emphasis during casting, and protect
expansion joints until the deck is opened to normal use.
SUB-CONTRACTORS:
Limiting work
to a select group of contractors, recommended by the expansion joint system
manufacturer, can be a huge factor in ensuring watertight joint seals.
These contractors are not likely to underbid the job resulting in
cost-cutting to make up losses. They can additionally be expected to
be properly trained to
install the systems and to address the substrate conditions that will help
to ensure
watertightness. Finally, these preferred contractors are likely to
versed in the communication process involving the Owner's Rep, Designer, GC,
and Manufacturer that is essential to success.
 MANUFACTURERS:
Specifications should be limited to manufacturers who continually
demonstrate a commitment to joint treatment, who have sound
technologies, the ability to ensure watertightness in plane and direction
changes, and a commitment to quality.
An unfortunate trend in the specialty
products industry is the loss to corporate conglomeration of formerly
focused, closely held, suppliers of various materials. The
result is the tendency of suppliers to try to commoditize these products
thereby removing much of the value essential to their proper performance.
In particular, the ability and willingness of manufacturers to offer
solutions for, and to fabricate watertight transitions in plane and
direction (such as up and down treads and risers), remains with only a
select few. Additionally, the industry has seen a trend in
membrane/nosing joint systems of cheapening the system by
massively aggregate loading the nosing material. The result is that the
material is supplied too brittle to handle temperature changes and impact
loading and results in premature failure.
Conclusion:
Without the cooperation of all involved and a shift in the relationships,
communication, and emphasis given to expansion joint treatment, stadiums
will continue leak.
In
contrast, projects like the under-construction Phillies Ballpark and Keyspan Park on Coney Island, have demonstrated that a different
approach can yield very positive and different results.
Sealing Stadium Expansion Joints—10-Steps to
to Designing Out Leaks
The
following guide offers tips for designing expansion joints in stadiums.
These combined with open and early dialogue with the expansion joint
manufacturer and expansion-joint specific dialogue with general and sub
contractors can result in dry stadiums and lasting expansion joint seals.
|
1) Acknowledge
the need for expansion joints—if you don’t put them in Mother Nature
will
Structural
materials have limitations. Cracks as the result of overstressed
materials are impossible to seal and can result in dangerous structural
weaknesses. |
 |
 |
|
2)
Choose carefully where you’ve put them
a)
Not at the corners.
Do not cast or use the connections of
precast bowl units at the corners or radii of the stadium bowl as the
place for the structural expansion joints.
These corners are impossible to set
while creating a consistent expansion joint-gap size. The angles
created in the corner make improper geometries for the attachment of
sealant systems. Instead, cast the corners solid or weld the
connections and make these connections cold joints. Make the structural
expansion joint in a straight line just off the corners.
b)
Not through planters. If you must then “double-wall” the
planters.
Never try to waterproof structural
expansion joint inside planters. If the joint runs through areas where
planters are designed, detail the planters with back-to-back walls
leaving the expansion joint sealable.
|
|
c)
Be careful through finished interior space
i)
Think about your interior layouts in relation to the expansion
joints. Make sure your interiors group knows where joints are and the
effect they might have on location of mechanical, plumbing fixtures,
etc.
|
 |
|
d)
Keep scuppers, and drains away from joints.
Roof scupper dumping water directly onto expansion
joint.
|
 |
|
d)
On ramps, locate the joint a the top of the ramp. Do not
expect that you can drain a deck down a ramp and over, under or through
the joint.
|
|
3)
Tell everyone where you’ve put them
Show expansion joints on all drawings-structural, architectural,
mechanical, landscaping
Include in specs, a specific reference for responsibility
of all trades to appropriate treatment of their work at expansion
joints.
Division 3 Addendum:
General Contractor Expansion Joint Responsibilities [.rtf]
|
|
4)
Select structural support wisely
a)
Choose split columns instead of
single-columns with slide bearing pads to eliminate shear conditions.
Top) Single-column
structure results in hard to seal conditions around column caps. These
should be avoided or will result in costly replacement.
(Bottom) FedEx Field,
Washington Redskins stadium required extensive retrofits just 3-years
after opening. EMSEAL's THERMAFLEX is being used to retrofit all joints
in concourses and will be used eventually in bowl as well. The added
cost of factory-fabricated transitions in this retrofit could have been
avoided however by designing with split or paired columns. |
 
|
|
5)
Think and design in 3-D
a)
Show Isometric Schematic of Joint Layout
i)
Cross-reference material selection for
each joint with cross-section details but…
Line-sketch schematic can be produced to show entire stadium and all
joints, intersections, etc. This will put the design-team on the
same page, allow the designing-out of potential problems, and
communicate expectations to general and subcontractors. This will help
ensure that the job is properly bid and constructed. |
 |
| |
|
|
b)
Show Axonometric details of each
transition in plane and direction
(L)
Blockouts prepared in parapet walls to receive transition from
THERMAFLEX to
SEISMIC COLORSEAL. Keystone Park, Coney Island, NY
(R) Factory-welded tread and riser
transitions in THERMAFLEX, Mumford Stadium, U of LA. |
 |
 |
|
6)
Once you’ve located them Size Them Properly
a)
Size in relation to Expected Movement, AND Temperature,
AND Movement Capability of Technology Type that will be used to seal
the joint, AND Tolerance Build-up
i)
Expected Movement--Calculate expected movement using the
coefficient of expansion of the materials in question, a realistic
concrete temperature range, and concrete shortening due to
post-tensioning if applicable.
(1) Temperature Range—A realistic temperature range for decks exposed
to the weather:
(a)
High Temperature = is the recorded high temp. for the city plus
20-degrees for solar heating.
(b) Low Temperature = the recorded low temp for the city.
b)
The fatal-flaw in the current communication paradigm is the
failure of the design team to ask the structural engineering a complete
question.
The most common sequence of events is
for Architectural to ask Structural “Where and how big?”. That is
“Where should the joints go, and how big should they be?” The problem
with this is that Structural will usually make a recommendation without
consideration of a material and its movement capability and other
effects on the joint design.
The better sequence should be for
Architectural to:
1-Select a technology
2-Take it to Structural and
3-Ask “Where and how big if I seal it with this?” |
|
7)
Make them Watertight
a)
Integrate with other waterproofing elements
Side-flashing sheets of
MIGUTAN system
integrated into deck waterproofing on split-slab deck to ensure total
watertightness over occupied space.
MIGUTAN
system in split-slab concourse joints at Keyspan Park, Coney Island, NY.
Provides watertight joints over occupied space below,
pedestrian-friendly surface, and is accessible for long-term maintenance
of sealing gland. |
|
|
b)
Transition from decks to walls, walls to roofs, etc.
Wall joint installed behind upturn of
deck joint results in water being funneled behind upturn. Fed Ex Field. |
|
|
8)
Write a tight, project-specific, defensible spec based on a
single technology or like technologies
Stadiums are no
place to be using the “cookie-cutter” approach to expansion joint
design. The spec for each job must match the performance demands of the
specific job. Do your research, design well, an write specs that
reflect your convictions. Then stick to them.
|
|
9)
Have Courage
a)
To defend proprietary specs on this tiny percentage of
the job
b) To hold the spec and not “roll-over” to contractor pressure for
substitutions
c) To stick to Nat’l Parking Association Guidelines for deck
maintenance especially snow plowing and make owner aware and build these
requirements in to into
snowplow contracts.
|
|
10)
Communicate
a)
Hold early and repeated meetings with GC and subs on expansion
joint issues such as:
i)
Forming joint-gaps in relation to temperature changes
ii) Solid form construction
iii) Proper consolidation (through vibration) of slab edges and
blockouts
iv) “Zero” tolerance on blockout formation
v) Finesse concrete work for blockout prep
vi)
Execution of concrete
work to handle transitions to vertical plane
Consider including this
language in your spec:
Division 3 Addendum:
General Contractor Expansion Joint Responsibilities [.rtf]
|
|
