You learn the most when you fail. Yet, in commercial construction, failure often isn’t an option.
The next-best (and certainly less-painful) way to learn is to study others’ mistakes.
“Lucky” for you, in the case of expansion joints, there’s no shortage of ways the product can falter. There are plenty of examples of good and bad usage for a variety of movement joint types.
This photo essay “memorializes” observations we made on a site visit. In addition to an autopsy of failed joints, you’ll see opportunities for improvement and recommendations for product replacement.
The goals? Avoid repeating history and build a longer-lasting, safer, system.
Overview: The project consisted of removal and replacement of an existing failed expansion joint system. The invasive mechanical anchors caused a fault line in the concrete on one side of the joint. The plate was then anchored in a similar fashion on the opposite side, causing another fault line in the concrete. This resulted in sections of plate “floating” above the joint.
Each time a vehicle passed overhead, the plate shifted. In some instances the joint was exposed, creating danger for pedestrians and vehicles alike.
What else will you find in this parking structure horror show?
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📏 Improper sizing |
⚠️ Long-term durability risks |
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🚧 Neglected transitions |
💦 Water ingress |
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🛠️ Improper maintenance |
🏗️ Wrong products used for site conditions |
Photo 1: A section of failed plate.
This was the highest-priority issue at the job site because it was on the first level. Also, there was occupied space underneath the level.
What ultimately caused the concrete to crack and fail? The plate kept popping off every time a vehicle drove over it.
On both sides of the joint, the anchors caused failures in the concrete. Repairing the concrete would require cutting back to sound substrate, creating proper geometry, and using fast-setting patching material.
However, even after repairing the concrete, installing the same joint would only cause the same failure all over again.
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Photo 2: A transition to a vertical, strip seal-style expansion joint.
This is where the movement joint goes over the side on the concrete structure’s first level. It’s the same joint line that runs across the parking garage in Photo 1, but a completely separate issue.
Yes, you can transition between new and existing expansion joints in concrete, but that doesn’t necessarily mean you should. Bear in mind strip seals are notoriously difficult to properly install and keep watertight.
This is why our product rec was a precompressed foam joint. In this use case it’d be better to replace all joint lines and ensure watertightness.
Photo 3A: A worm’s-eye view of a fire blanket “protecting” the underside of the joint termination from photos 1 and 2.
Sometimes a failed joint is a simple matter of using the wrong type for the job site. This could mean inadequate sealing material, or it could mean relying on … bedding?
This is Level 1 of the parking garage, and there’s occupied space underneath, so fire-rated protection is a must.
Someone decided the answer was to shove a folded-up fire blanket inside to act as protection. In the modern era of construction code, that doesn’t fly. Use of fire blankets was actually common practice prior to the existence of fire-rated precompressed foams. The install itself wasn’t bad here – but it’s a serious risk if the joint isn’t properly designed, installed, or maintained.
Photo 3B: The same termination, seen from above.
This is a simple termination for either joint, but the end will require a silicone coating. Typically, this happens via preapplication back at the factory.
Generally, once product systems get wet, their fire rating is greatly diminished. It looks like a wet blanket won’t get the job done this time around.
Product Rec: Fire-Rated System (Not a Blanket)We’d recommend a 2-hour, fire-rated expansion joint that also protects against seismic activity. This product material is able to withstand flames for 2 hours before failing. This product has the same essential design as the standard seismic joint system, but with a fire-rated impregnation and intumescent coating on the underside. Intumescent coating expands and thermally insulates the surface, slowing the spread of fire. With the right product, no additional fire blankets or steps are necessary to achieve a fire-rated, watertight expansion joint. Again, you can install this with or without nosing material. |
This project was a fairly old structural installation. But it wasn’t old enough to justify these types of expansion joint failures.
Photo 4: A joint at a stair tower with frequent pedestrian traffic.
This is what happens when the gutter drains get clogged.
The old joint system didn’t receive much TLC. As such, the sitting water in the gutter deteriorated its surroundings over time.
The proposed new system would keep water out of the joint altogether. This would in turn eliminate the need for gutters and other maintenance items.
Also note the invasive anchor failure in the cover plates. Replacing these joints would also restore pedestrian safety.
Pro Tip: One simple way to slow the degradation of joints is consistent and proper maintenance – especially snow removal. There are also products available with improved protection against this type of deterioration.
Photo 5: A failed precompressed foam horizontal expansion joint connecting the exterior stairwell to the main space, where users cross to get to their cars.
Every expansion joint is custom-made to order – they’re not a one-size-fits-all solution. Poor understanding of concrete expansion joint spacing can lead to improper sizing and settling of the structure.
At this site, the joint product was too small for the space. An expansion joint should be very snug, rather than relying on sealant to do all the work. The force of the joint may have broken the seal here – you can’t expect sealant to hold a gap that big.
Simply removing the existing joint and replacing it with the correct material size would solve the issue.
If nothing else, these job site photos show the value of taking expansion joint buying and installation seriously.
What did we learn from this history lesson?
Both product recommendations (in the blue-shaded boxes) offer the fastest installation of any expansion joint system out there. Downtime for the garage would be minimal. The installation would take place completely from above, so there’d be little to no disruption to the occupied spaces below, either.
Enough with the bad news! There are lots of success stories of using expansion joints and other commercial-grade products. See our project portfolio for more case studies: