Polyurethane Construction Sealant

Polyurethane Construction Sealant

A smooth, odorless and gun-grade mastic sealant that is ideal for movement sealing applications. It’s used for concrete expansion joints, curtainwall joint caulking and basic perimeter sealing of windows, doors, skylights, framing, and other masonry.

This one-component, moisture cure product forms permanent elastic seals that are paintable and abrasion resistant. Compares favorably with silicone sealants.


Unlike silicone sealants, polyurethane construction sealants can be painted over after curing, giving you more options when it comes to aesthetics. Additionally, these sealants are resistant to weathering and can last for up to 20 years. This means you won’t have to worry about replacing the sealant as often, which is important if you work outdoors.

When you’re sealing joints in concrete, you need a durable product that will hold up over time. That’s why a polyurethane construction sealant is the way to go. These products are made of high-density foam that can withstand the elements. They also have a strong bond with concrete and other materials. They can withstand repeated exposure to water, humidity and sunlight without deteriorating.

Polyurethane construction sealants are available in a variety of colors, textures and strengths to match your project’s needs. They’re also easy to apply with a caulking gun. This makes them ideal for use on concrete, masonry and metal surfaces. They’re also easy to clean up when dry.

If you’re looking for a low-modulus, one-component moisture curing modified polyurethane, try CRL M64. This product is formulated to outperform traditional VOC solvent polyurethanes and can be used for a wide range of applications. It’s ideal for sealing dynamically moving joints in concrete, masonry and metal, curtain wall joint caulking and basic perimeter caulking. It can even be used as a bedding sealant for mullions, doors and panels.

Moisture Resistance

The moisture resistance of a construction sealant is one of the key factors that determines how long it will last. For example, if you seal a joint with silicone caulk and it is exposed to the sun’s UV rays, it will quickly break down, but a polyurethane sealant will be able to stand up to this exposure.

This is because polyurethane sealants are made from organic material. In contrast, silicone sealants are made from inorganic materials, which is why they are less durable and can’t withstand UV rays or extremes of temperature.

For this reason, it’s important to polyurethane construction sealant choose a high-quality construction sealant that is designed to withstand the conditions in which it will be used. In addition to being able to withstand the effects of moisture, it should also have good adhesion and flexibility. This will ensure that the sealant stays in place and is not compromised by movement or shear.

A construction sealant should be able to bond a variety of different substrates, including concrete, wood and metal. In order to get the best results, it’s important to prepare the surface before applying the sealant. This includes removing any dirt, dust, rust or brittle paint. Once the surface is clean, you should apply a primer before using the sealant.

A great choice is CRL M64 Modified Polyurethane Construction Sealant, which can be used in a variety of general construction applications. This is a gun grade, moisture cure, non-sag and flexible polyurethane sealant that can be used as a barrier to water penetration and weathering. It has excellent adhesion to glass, fiberglass reinforced plastic (FRP), galvanized metal and masonry. It is also compatible with most fluoropolymer paint coatings for metal surfaces, including KYNAR® and Duranar® coatings.


The ability to bond to substrates is an important factor in determining the polyurethane construction sealant performance of a construction adhesive. Polyurethane construction adhesives and sealants bond strongly to concrete, masonry, metal, fiberglass, wood, vinyl, rubber and most painted surfaces. Some can even be used on wet or frozen surfaces.

Most polyurethane sealants are also available in a variety of colors to match or complement the surface color. Additionally, some are designed to resist UV radiation. Because UV exposure degrades organic materials, this is an important consideration in some applications. For example, a moisture cure polyurethane adhesive that is used in finish carpentry adheres the corner joints of trim framing for doors and windows. This prevents the expansion and contraction of those joints caused by temperature and humidity changes. This can reduce call-backs to the builder and also help to protect those corners from premature damage.

In addition to providing excellent adhesion to a variety of substrates, most polyurethane construction adhesives are easy to apply. The majority can be applied by a caulking gun, which eliminates the need to mix components, fill cartridges or pre-heat or thaw equipment. Most also require no primer for most materials and provide tack-free and final cure times that fit the needs of the job.

Some types of urethane construction adhesives are formulated to eliminate the need for hole-drilling. This can be particularly helpful for engineered lumber that is dimensionally stable and flat, such as composite lumber. This type of adhesive can also prevent surface damage caused by the use of mechanical fasteners. This can be a significant time and cost savings for the contractor.

Ease of Application

Compared to caulking, sealants are much more flexible and can be used in tight spaces. They also provide a strong bond, so they can keep materials together. Whether you need to bond metals, wood, glass or concrete, polyurethane construction sealant can help you get the job done.

There are many different types of polyurethane adhesives and sealants available on the market, each with its own unique features. For example, some are self-leveling and designed to seal floors. Others are rated for use in outdoor structural applications. Many are compatible with most surfaces and can be painted to improve the final finish. Before applying, it’s important to prepare the surface and follow product instructions for the best results. Surfaces should be free of dust, grime, grease, rust and brittle paint. Some products require a primer, so be sure to check the packaging for details.

One popular type of polyurethane construction sealant is Sikaflex-1a. This is a premium-grade, high-performance, moisture-cured elastomeric sealant that can be used in a variety of construction applications, including small joints and fillets, windows and door frames, reglets and flashings, as well as common roofing detail applications.

Another type of polyurethane construction sealant that is available is Akfix PU Construction Sealant. It offers maximum UV resistance, so it will not degrade over time due to prolonged exposure to sunlight. It also resists changes in temperature, which is an important characteristic for any construction product.

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