What is Butyl Caulking Sealant – How to Use It?

You probably have used caulk to seal up cracks in the walls and joints of your home – it’s simple to use yet quite effective and can last many years when properly applied.

But Butyl Caulk is a bit different. At its core, Butyl Rubber Caulk is a sealant made of elastomer that can be used on various types of building surfaces and construction materials outdoors, such as metal, glass, wood, brick, and stone.

But what makes this type of caulking different and well-suited for exterior use? What are its primary applications, and how do you apply them to cracks or gaps? Let’s get into all these details below…

Butyl Caulk

Butyl Sealant is a formula that is a unique blend of butyl rubber and polyisobutylene, providing a highly flexible, pocket-friendly sealing solution.

Butyl caulking differs from acrylic latex caulk (used on interiors) because it contains elastic butyl rubber, which is quite effective at naturally waterproofing outdoor surfaces by resisting the elements. This means once the caulk cures in the gap or crack, it will not only prevent water from entering but will also be able to shrink or expand to keep the gap filled.

Depending on the brand, some of these super-elastomeric sealant formulas are paintable and can also be applied to cold or damp surfaces while still retaining their excellent adhesion.

Butyl Caulking Uses

Being both waterproof and weather-resistant, Butyl caulking is primarily designed for exterior use for sealing around roof vents, drain spouts, chimneys, gutters, flashings, and other harder surfaces exposed to the elements.

Although many other caulking materials can offer similar advantages, an additional benefit to butyl is that it can bind with so many different types of materials like…

• Concrete
• Glass
• Masonry
• Metal
• Wood

The type of versatility Butyl caulking offers means you can start on the corrugated roofing of your home (to seal joints or fill up cracks) and then use it around the chimney to seal the gaps and keep the water out.

You can then move down to the walls and use it on the aluminum siding or window trims to plug the gaps. Also, you can go into your basement or outdoor foundations to address issues affecting the concrete.

Butyl rubber caulk is also a reliable vibration dampener, often used in vehicles to reduce tremors. Thanks to its remarkable capacity to absorb shocks and disturbances, you can use it on your car, RV, boat, etc., as an effective vibration-reducing solution.

Also, if you’re looking to use it for sealing mobile homes or skylights or need a vapor barrier applied – this caulking would work very well.

How to Apply Butyl Caulking? 

Applying butyl caulk is no different than applying other caulk types. But you need to wear proper clothing and protection. This means long sleeves, gloves, and eyewear so the caulk does not touch and stick to the skin or the eyes.

The area where you are applying the caulk should also be well-ventilated. If you are outdoors, this should not be an issue, but if you are indoors, such as in the basement or garage, use a fan to circulate the air and wear a respirator.

Step 1- Clean the surface

For caulk application, start by cleaning the surface by removing any loose mortar, dust, and old finishes that might be peeling or otherwise compromised.

If needed, you can use a power washer or a wire brush to scrub thoroughly to ensure the surface you are working on is clean and free of loose material.

If mold is present, treat it with a mixture of one part bleach and ten parts of water. Spray on the solution, let it kill the mold, then wipe away the remains or rinse using a power washer and let it fully dry. Once the area is clean and dry, you are ready to apply the butyl caulk to the crack or gap.

Step 2- Set and test the caulk

To be fully effective, the temperature must be between 40- and 120 degrees F – the butyl caulk will not properly stick to the surface well if it is too cold or hot. 

You don’t need to cool your caulk before applying if the temperature is higher. But in extremely cold climates, butyl rubber caulk tends to harden quickly, which makes it challenging to get out.

So, if it’s on the colder side, simply let your butyl caulking tube soak in warm water for around 20 minutes to warm it and soften enough to be squeezed out of its container easily.

Once done, cut the tip of the tube at a 45-degree angle. Load it into the caulk gun and squeeze the trigger to test for the proper flow on a paper or cardboard that can be discarded once the testing is complete.

Step 3- Apply the butyl caulking

After testing out your caulk tube, point the tip at a 30-degree angle toward the opening or crack you wish to fill. With steady pressure, slide it along the length of the gap and continue until completely filled. To clean up any messes, ensure even sealing, and for smoothing purposes, use a putty knife.

Allow the caulking to dry for two-three hours and thoroughly inspect the gap afterward. In case any area has been left out, apply a second coat of butyl caulk in an even manner. Doing this will seal off all crevices from moisture and other elements, which is essential for successful protection against humidity.

How Long Does Butyl Caulk Last?

Butyl caulk is an ideal choice for those seeking a long-lasting and strong seal that can withstand changing weather conditions for decades.

Unlike acrylic or silicone caulking, its butyl rubber component ensures the caulking remains intact even in extreme temperatures, and will likely last for many years.

However, it’s recommended to inspect the caulk at least once annually to verify it has not cracked or flaked away; if you notice any deterioration of the sealant, remove it entirely before re-caulking as necessary.

How Can You Remove Butyl Rubber Caulk?

Although solid and long-lasting, you can remove butyl caulk with the right tools and techniques once it’s applied.

• Use a utility knife to cut through the butyl caulk edges from the surface
• Pry up the caulking sealant with a putty knife, angling it at 45 degrees
• Use your fingers to grab the peeled caulk, then pull it up and out
• Repeat the above steps until you have removed all of the butyl caulk of the surface

After removing the butyl caulk, if you need to apply the fresh caulking layer, soak steel wool in mineral spirits and use it to scrub the surface. If you don’t remove all residues, the new sealant won’t stick correctly.

The Bottom Line

Butyl caulking is the perfect solution for cracks and gaps measuring ¼-inch or larger. Its formidable binding properties allow it to adhere tightly onto many materials used in domestic, commercial, and structural structures – particularly metal roofs with joints that may be subject to expanding and contracting during weather fluctuations.

When applying just make sure you select the right type of caulk for the job, follow the instructions provided on the packaging and keep an eye on both temperature and humidity. This will ensure a successful application and tight seal that will last for years.