Types of Building Sealant Joints

Sealants are used to fill cracks and openings in a structure and prevent air, water, moisture, gases, noise, dust or smoke from entering.

The correct sealant is a critical component of any building project. It needs to perform under the anticipated conditions of use such as movement, temperature, light and water.

Expansion Joints

Expansion joints are a critical component of building sealant performance because they protect big gaps and keep water, chemicals and other contaminants out. They’re also a vital piece of structural integrity that helps reduce damage caused by movement, temperature variations, static loads and other forces.

There are many different types of expansion joints and they are used for a variety of applications. They’re especially useful for protecting masonry and concrete surfaces from cracking.

In addition, they help a structure withstand earthquakes. This is because they allow heat-induced movement to occur without damaging the surrounding materials.

These gaps are also used in piping systems to absorb shock and vibration, and they lessen noise in the system. They are a key part of plumbing systems, but they can be found in other industrial and commercial applications as well.

A variety of factors must be considered when selecting expansion joints for your project. First, the location where they will be installed is important because it affects their overall durability.

It’s also important to choose the right material for the job. This includes the underlying medium that passes through the joint and the add-ons such as flow liners or insulation that provide added defense against contaminating media.

Another consideration is the pulsations and pressure changes that may happen in a pipe during its Building Sealant discharge. These pulsations and pressure changes can cause the joint to wear prematurely.

The best way to protect your building’s joints is to ensure they are properly sized, designed and fitted with a high-grade joint sealant that is resilient to temperature fluctuations and has the ability to bond to masonry, steel and other common construction materials.

For a long-lasting, effective installation of these types of joints, make sure you work with a contractor that is well versed in these types of sealing systems. They will be able to address substrate conditions and install the joints in accordance with manufacturer’s installation instructions. They will also be able to perform a proper inspection on your project, which will ensure your joints are performing as intended.

Window Joints

Window joints in a home are a common place where building sealant is used. These gaps are often caulked around the rough opening, which provides an air-tight seal that makes the home more comfortable in various weather conditions.

There are several types of building sealants that are used in different construction applications. They range from water-based sealants that are often found in homes, to polyurethane foams that are popular with contractors because of their superior insulation properties.

The most common type of building sealant is a water-based latex product, which is easy to apply and paintable. They’re also easy to clean and dry quickly.

Another option is acrylic solvent-based sealants that have excellent adhesion to a wide variety of substrates. They’re also weather-resistant, stain-resistant, and UV-resistant.

These are good choices for sealing gaps between moldings and doors, or between a wood frame and the exterior of a home. They’re also a good choice for sealing the joints between wooden windows and a concrete foundation.

In addition, there are specialty sealants that prevent flame and fire egress from one wall to the next. They’re usually made with a non-flammable backing material, which is often a foam strip.

There are also specialty window and door sealants that can help prevent the rusting of metal. They’re especially useful for older windows that have rusted from exposure to the elements.

They’re also important for keeping rainwater from leaking into the window frames. They’re typically applied to the interior and exterior of the window frame, as well as the outer edge of the sash.

When choosing a window or door joint sealant, consider the width and depth of the joints between the parts. These should be wide enough to accommodate a movement and still have enough depth to bond properly with the substrate.

The depth of the joints should be a minimum of 1/4 inch (6 mm). This is to ensure that the sealant flows into the joints properly when applied with a caulking gun.

It’s also important to note that certain sealants – like those designed for structural glazing – need accelerated testing to demonstrate their performance in such applications. These tests involve a combination of UV exposure and time in the sun.

Door Joints

Door joints are often used on the interior of a building to allow for the movement of door components. They are also used to attach structural glazing to a flange or brickmold. Sealants are a necessary component of these jointing applications, and the selection, application, and curing of the appropriate product is critical.

The physical and chemical properties of the sealant, its adhesive and cohesive strength, stress/strain recovery, and tear strength are all important. Additionally, the sealant’s aging characteristics and its ability to adhere to various substrates and resist moisture, temperature extremes, cyclic joint movement, movement during curing, and bio-degradation all influence its durability in a joint.

Some of these properties are tested in the laboratory, while others require a sealant to be exposed to the environment and evaluated on site. The most difficult test for a sealant is the ASTM C719 Durability of Adhesion and Cohesion to Cyclic Movement in Elastomeric Sealants which tests the sealant under cyclic movements. This is Building Sealant a very demanding short term performance test, but can help to give a more realistic idea of what the sealant will be able to do in a less demanding application.

Another short term performance test is ASTM C736 Test Method for Adhesion and Cohesion of Construction Joint Sealants Under Continuous Extension to Compression, Back and Forth. This consists of making the joint, curing it then extending it to +25% of its original width for 5 minutes, releasing the strain and watching to see the recovery of the adhesion.

The backer rod is a thin strip of material, that is inserted between the two materials of the joint. The backer rod prevents three-sided adhesion, which can lead to joint failure. The backer rod is usually made of PVC and can be a variety of shapes, sizes, and textures. The backer rod must be installed correctly, so that it does not puncture or create a void that may cause outgassing of air during typical day to day temperatures and sunlight.

Sealant applications that involve the use of a backer rod need to be well thought out and designed, as they can cause problems for the joint itself, the door and frame, and the building. This is why it is important to select the correct backer rod for the application, and to follow the instructions for installation carefully.

Roof Joints

Roof joints are the connection point where the rafters, beams and purlins meet. Historically, these connections are made by dovetail joints, dowels or wedges. They are used to strengthen trusses. These types of joint designs are common in historic wood structures, especially in Eastern Poland and Western Ukraine where they were used for churches, monasteries and other religious buildings.

These are also commonly found in residential constructions of the 13 th and 14 th centuries. They are characterized by a relatively wide gap width and a change in the size of the gap when loads are applied, known as movement.

The key to selecting a joint sealant is the ability to handle the movement and the size of the opening. If the sealing capacity of the sealant is too large for the opening or not wide enough to properly place the sealant then the joint will not function correctly as designed.

It is also essential that the sealant is able to withstand a changing temperature range, particularly for thermally driven movement. This will change the physical properties of the sealant, which may cause adhesive or cohesive failure.

Another consideration is whether the joint is exposed to moisture, which can lead to sealant outgassing. This can happen if the backer rod is punctured or if the sealant is installed directly over the backer rod before it has a chance to wick moisture into the foam.

In any case, the proper design and placement of the sealant must allow for sufficient voiding for air to escape. Ideally the sealant should be able to open to at least 50% of its design range to give the installer sufficient access to the joint without having to use an additional strip for bridging the gap.

If the joint is too narrow for the opening to accommodate a full thickness of the sealant then it is important to consider a pre-cured strip that bridges the gap between the substrate and the joint as the joint expands. This is especially important when the joint has aluminum or glass substrates that cannot be cut out to make a larger joint.