How to Apply Exterior Caulking

Exterior caulking is a great way to save hundreds of dollars on heating and air conditioning and prevent your building from deteriorating prematurely.

Without effective exterior seals, air exchange can hamper your HVAC system and moisture and water infiltration can damage the building materials.

In this article, our caulking specialists provide all the information you need to seal your building effectively.

Where to apply exterior caulking

There are many areas on the outside of your building that can benefit from caulking joints:

Around the perimeter of doors and windows

It’s vital to seal the exterior of windows and doors to make them as airtight at possible. Seal around the perimeter of windows and doors where the frame meets the exterior siding and under the window sills.

If you like, you can even caulk the doorsteps.

Areas where walls meet at an angle

The walls of a building can expand and contract with changes in temperature and humidity. This phenomenon can cause gaps to appear between walls that meet at an angle.

By sealing these joints with a product that retains its flexibility in adverse weather conditions, you can prevent air and water from infiltrating through the openings.

Wall fixtures and electrical outlets

Areas with wall fixtures and exterior electrical outlets are vulnerable to water infiltration.

Seal the joints between the fixtures and the exterior siding to prevent water from finding its way into the building. For exterior outlets, remove the protective plate and caulk around the electrical box.

Minor cracks in the foundation

Small cracks in the foundation are normal and don’t usually indicate larger structural problems. However, even small cracks can allow water to accumulate in the concrete, causing it to deteriorate prematurely.

Seal small cracks in your foundation with an appropriate waterproofing product to prevent water infiltration and damage.

All components that go through your exterior walls

The fact is that any opening can let cold, moisture and water into your building. That’s why all holes in the exterior walls that are designed to accommodate cables or pipes should be sealed.

Don’t forget to caulk around:

  • Plumbing pipes
  • Gas pipes
  • Electrical cables
  • Dryer vents
  • Exhaust hoods
  • Air conditioners and heat pumps
  • Etc.

Steps for effective and appealing exterior caulking

Not sure how to apply exterior caulking that will enhance the appearance of your building and keep it airtight for years to come? Here is a 5-step exterior caulking procedure to follow for best results.

1 – Clean the area before caulking

Thoroughly cleaning the area before caulking it is a good way to ensure that the sealant adheres to the building material as well as possible.

If you’re planning to reseal old exterior joints, you’ll need to start by removing the old sealant with tools such as a utility knife and a scraper.

Use a cleaning cloth soaked in an alcohol-based cleaning agent to clean the surfaces you’re planning to caulk. The alcohol will act as a solvent, breaking down oil residue and other contaminants. Then, you can simply wipe off the debris and wait 20 minutes for the surfaces to dry.

2 – Apply primer

Sealants don’t always adhere well to the materials used to construct the exterior of buildings. The problem can be rectified by applying primer to the clean surface before caulking it. This will produce a longer-lasting result.

3 – Place backer rods in the large gaps

For gaps more than a quarter of an inch (around 65 mm) wide, it’s a good idea to place backer rods in the opening before applying the sealant.

That way, it will be easier to control the depth of the joints and make them the correct hourglass shape.

4 – Apply the sealant

Before applying the sealant, make sure the one you have is designed for the use you have in mind. Neutral cure silicone adhesive sealants like the Adseal DWS 4580 series are great for outdoor use.

These types of sealants generally adhere very well to exterior building materials such as aluminum, glass, masonry, certain plastics and painted and unpainted metal. They also have excellent UV resistance and retain their flexibility and volume when subjected to changes in temperature and humidity.

It’s important to note that silicone sealants cannot be painted. Feel free to use our colour matching tool to find a silicone sealant that matches the style of your building.

To save time and energy, you’ll want to use a caulking gun to apply your sealant. Once you have your caulking gun, insert a cartridge of sealant and cut the tip at a 45-degree angle. Remember—the closer to the cartridge you cut, the wider your line of sealant will be.

With the nozzle opening parallel to the surface, apply lines of sealant in 2 to 3-foot segments so that you can shape them before they dry. Keep constant pressure on the trigger to distribute the product evenly.

5 – Shape the joints

You’ll need to shape your joints to remove excess sealant and give them a smooth, neat appearance. Use a shaping tool or wooden sticks to facilitate the process. Simply place the tool at an angle and slide it across the sealant, maintaining consistent pressure.

Adfast: your resource for top quality caulking products and expert advice

Now you’re ready to put our exterior caulking tips into practice and make your building airtight!

If you have any more questions about how to apply exterior caulking or which products to use, don’t hesitate to contact our specialists or check out the News section of our website.