Most people think of buildings as a static feature of the environment. They don't realize that buildings move, just like you and I. (Well, kind of like you and I.)
Expansion joints play an underappreciated role in managing structural movement. They’re also an overlooked maintenance item. (This lack of respect is odd, seeing as they’re also called … movement joints.)
Proper use means less chance of leaks, mold development, structural degradation, and premature failure of critical building elements. In other words … it’s important to know how to install expansion joints properly.
Let's focus today on the popular and successful foam-style joint.
Using a foam expansion joint and sealant requires knowledge and planning. This checklist will provide a reliable measure to apply to any project, keeping your process consistent and your chances of bond failure at a minimum.
Construction progress rarely happens in a straight line. Nonetheless, having a clear understanding of the owner’s preferred aesthetic, pricing, and deadline may help prevent circles (or downward spirals).
Typically, the vertical joints in a building are meant for precompressed foam, but sometimes builders opt for lower-cost alternatives. When you do that, however, you can – and will – run into issues with the look and performance.
One example we sometimes see is that the joint is too wide for the lower-priced alternative. Eventually the building owner will recognize that and order you to find a solution that provides an appealing visual (and performs as expected).
If you find yourself in this situation, you’ll soon have to address why the joint’s cost is suddenly $100/linear ft. instead of $35 per lineal ft.
We find it’s easier to justify the cost upfront – simply give the explanation that precompressed foam is easier to install and requires less labor. The reassurance of a better aesthetic upon installation helps as well.
Note that foam movement joints are typically priced by different widths as well. Before you order material, verify the joint dimensions in the field. On projects with varying joint widths, it may be possible to consolidate sizes of material. Consulting with an expansion expert can save you time and money here.
Last, but not least, always order ahead of time. All foam expansion joints are custom-made to order.
Precompressed foam has its benefits – but it comes with a need for closer attention to storage and a better plan for use.
Temperature plays a major factor in installation for precompressed foam joints. Cold weather will prevent expansion, and the product won’t fill the joint correctly. In warm weather the product will expand rapidly if you don’t store it properly, preventing installation altogether.
Example: On a 1” joint you want to fill, this product is precompressed to ¾. When you place it in the joint, it’ll expand to four times the amount of the 1” in. joint. So if you don’t do something with it immediately, it’ll expand to 4” while it’s lying on the ground – which is not helpful.
On cold days, make sure your movement joint sealant is off the floor and inside where the temperature is above 68°F. Sealant recovers faster when warm. Meanwhile, on hot days, keep the sealant out of direct sunlight (on days where the temperature is higher than 60°F) until just before you apply it.
The time to make sure you have all of your tools ready is before you start applying the sealant. The process is quick, and the right tools make it a lot easier to accomplish. While you may not need every tool for every install, it’s best to have them close to hand just in case.
Tools include:
Note: For overhead work or large joints, it’s helpful to have spare 2x4s and screws to fashion supports. Occasionally, if a stick expands past the opening size of 6’, a 2x4 will help get the whole joint in.
If the inspection reveals challenges such as irregular joint widths or complex angles, plan for how to address these during installation. This may involve using specialized tools or techniques to ensure a proper fit
Water and temperature are two considerations in any environment where you are applying foam expansion joints. For areas where moisture is a threat, waterproofing is a necessity.
Using sealants in conjunction with foam expansion joints for additional waterproofing means applying them evenly and according to the product instructions. The best approach is to ensure full coverage, avoiding gaps that could allow water penetration.
Extreme temperatures can affect the material's flexibility and the curing process of any sealants. Make sure to install foam expansion joints under suitable temperature conditions. Even in modest heat, prolonged sun exposure can interfere with effective installation.
Likewise, if it’s too cold, the curing time doubles with every 10-degree drop.
As you’re determining how to seal your concrete expansion joints, another part of the system to consider is the cover. A DSM (dual-seal membrane) system, for example, provides a watertight seal across expansion joints in structures like parking garages, bridges, stadiums, and other large-scale construction projects.
The "dual seal" aspect incorporates two layers for enhanced protection against water ingress. This design is particularly important in applications where water leakage could cause significant damage or where high levels of durability and reliability are a must.
Cleaning and drying ensure that the foam expansion joint adheres properly and performs as intended. Dirt, debris, or moisture can compromise the adhesion of sealants or the positioning of the foam joint, leading to potential failure and water ingress. The surfaces should be smooth and free of sharp edges that could damage the foam during installation.
Tips for cleaning surfaces:
Install the foam expansion joint with the correct level of compression as recommended by the manufacturer. Over-compression or under-compression can affect the joint's ability to accommodate movement and maintain a watertight seal.
During installation, provide pressure between the sticks. The easiest way to achieve this is to:
During repairs, cut the repair section a little long and bow the middle of the segment upward. Once that area is pushed down, the correct amount of pressure will be in effect.
Once material expands beyond the joint width, it can be impossible to get into the joint.
Remember: Many foam expansion joint materials are compressed for packaging to save space and facilitate easier handling and shipping. Cutting the material to the required length while it's still in its compressed state and packaging ensures that it doesn't expand or stretch prematurely, which could make it more difficult to handle and install accurately.
Cutting to the correct length while it remains in the package helps maintain the integrity of the foam joint until it's ready to be installed, reducing the risk of deformation. The packaging helps to keep the material straight and manageable. This can lead to more precise cuts and efficient use of material. By cutting to the exact needed length beforehand, workers can then quickly move from one installation point to another without the need to adjust material length on the spot.
Keeping the expansion joint material in its packaging also protects it from:
Installing the foam joint at the correct depth is essential for its effectiveness in accommodating expansion and contraction. The depth of an expansion joint is typically determined by the type of joint system you’re installing and the specific application.
For example, in a building facade, the depth of the joint needs to accommodate not just potential movement, but also any materials or sealants used within the joint. Manufacturers often provide specifications for the optimal depth based on the joint system's design and the expected movement.
Due to the complexity of predicting structural movement and the potential consequences of incorrect depth, get professional guidance when you’re not 100% sure. A distributor with technical expertise can explain how each product type and job site influences ideal installation depth.
It’s safe to assume that there will be at least one change in direction as you install sealant into joints on your construction project. In the event this occurs, knowing the plan well before you start installing is the best way to achieve success.
For all 90° changes, each piece should be cut at a 45° angle and then joined. Another option is to notch the foam out and bend the stick at the change in plane.
When you correctly deploy a foam expansion joint, it’ll provide a snug fit and support its weight in the joint. However, depending on the type, an adhesive might be necessary.
If this is the case, a caulking gun and silicone are your answer.
Pro Tip: Silicone left between the wrinkles of the bellows could constrain movement -- be sure to remove excess sealant and blend what remains into the bellows.
If you now know how to install concrete expansion joints, this should be the easiest step!
Before you call the job complete, go back over what you just installed and inspect carefully (particularly where new sticks begin). Having the property owner angry or disappointed with the job – either that day or in 6 months – isn’t worth cutting corners.
It’s also not ideal to have to revisit the site and redo some of the work because you didn’t check it when it was complete. Some issues can be resolved quickly if they’re found immediately and not left to amplify over time.
Don't reopen anything before the product is ready. Allow the sealant to skin over before you expose it to traffic (where applicable).
Once you become comfortable with the above checklist, the recurring red flags will be apparent very quickly at each new job. You’ll know where you need more time or to plan for angle changes, you’ll know whether you need adhesive, and you’ll have far less chance of angering the property owner.
Knowing how to install a foam expansion joint – and when it’s the best option – is half the battle. However, if you have more questions related to joints and sealant installation, we have additional expert resources available: