Sealing Gaps Around a Dryer Vent in Easy Steps

The venting system starts at the exhaust pipe that connects to a vent inside the house, before connecting to ductwork at a wall opening and extending outside the house. The outer part has a vent cover that keeps away dirt, debris, and insects.

Things can get complicated where the ductwork extends to the roof. Unfortunately, not every day you’ll climb over the roof to check if there is a bird or rodent invasion. Likewise, gaps around the dryer vent are potential fire hazards when lint escapes.

Lint is the small particles from the laundry that are emitted alongside the hot air. These can ignite a fire when they rub upon surfaces. You can prevent such a scenario by sealing gaps around a dryer vent using the suitable sealant material. In the discussion, you’ll get all the information on how to seal gaps around a dryer vent and the materials to use. Keep reading.

What do you need?

You will need the following items for this task:

  • A microfiber cloth
  • Caulk chalk, preferably silicone
  • Caulking gun
  • Dry cloth
  • Tape measure
  • Spray form
  • Safety goggles
  • Gloves

Sealing Narrow Openings

Sealing narrow gaps is much easier than wider openings. You can use silicone caulk which adheres well to surfaces, especially clean and dry places.

The advantage of silicone is that it flows out of the tube effortlessly and seals the crack. It’s also flexible, and I suggest checking the instructions as some manufacturers may recommend silicone for indoor use. Also, some types may not work well in cold temperatures.

If you don’t have silicone, you can also use low expansion spray foam to seal small gaps. Check with your local hardware for availability.

For outdoor caulking, you need a product that can withstand both hot and cold conditions. Before you climb over the roof, you’ll need to wear protective equipment in case of falls and accidents.

  1. Start by removing the vent cover by unscrewing it with a screwdriver. If there is a lot of debris, remove it with your hand and use a lint brush to clean the dust.
  2. Next, wipe the opening with a damp cloth.
  3. Using a tape measure, estimate the width of the opening.
  4. Load the caulking gun with caulking material and use a utility knife to trim the edges in small bits until you get the right size that will accommodate the caulk.
  5. Using a caulking gun or squeezable tube, apply the silicone caulk bead around the opening. Fill the entire opening between the wall and the pipe.
  6. Since silicone caulk doesn’t shrink or expand regardless of the weather conditions, ensure you fill the entire gap.
  7. For any spillage around the walls, wipe with a dry microfiber cloth. Sometimes, the caulk may dry, and using a utility knife, peel the excess material. You can use screws to tighten unfastened flashing and apply the sealant around the area.
  8. After that, clean the residues using a paint thinner or mineral spirits. The silicone will take approximately eight hours to cure before exposure to water or paint.
  9. Finally, replace the old vent cover with a new one

Sealing Wider Gaps

Silicone caulk works best for narrow gaps; however, you can use spray foams for medium to large cracks. For this task, you need to put on gloves and safety goggles as the form contains chemicals that can irritate the skin.

There are different types of spray foams, and when shopping, look for the recommended agent for sealing gaps or openings. The most common types are high and low expansion.

  • Start by removing the vent cover and clear the debris from the opening.
  • Next, wipe the dirt using a damp cloth, just like silicone spray foam attaches well to clean surfaces.
  • Remove the spray tube from the spray foam container’s side and insert it into the small opening on the top surface.
  • Direct the spray tube into the opening between the wall and dryer vent.
  • Push the trigger on the can and release the foam around the vent. Unlike silicone, spray foam can expand after curating to around 25% of the application. Therefore, don’t fill but leave some room for expansion.
  • Then, give the foam at least 24 hours to cure and curve out the excess with a utility knife.


Besides emitting hot air and lint, the dryer vent can house rats, insects, and birds. Cracks can cause the dryer not to run efficiently, which can increase your power bills. Worse still, when lint escapes to the gaps, a fire can occur, leading to loss of property and life.

Therefore, it’s essential to seal the holes using a suitable sealant material. In our discussion, silicone caulk is best for closing narrow gaps, whereas spray foams work well in larger openings. Finally, ensure your compound is clean as rats can chew the calk or foam material and apply caulk on the screen to prevent air leakages.

I am a cleaning enthusiast and a writer for renowned cleaners guide sites. I am the Chief Executive Officer for All-City Janitorial and All-City Duct Cleaning. This is where I write about my exploits in detail to share my experience with everyone.

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