Expansion Joints and Pre-Compressed Sealants



STADIUMS LEAK--But is there an alternative?

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.  Joints are, by and 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 be 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 massive aggregate loading the nosing material. The result is that the material is supplied too brittle to handle temperature changes and impact loading that results in premature failure.

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. 

e)  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]


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EMSEAL LLC. 120 Carrier Drive, Toronto, ON M9W 5R1



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Last Modified: April 26, 2015

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