How to Use Flex Seal Products to Keep Mice and Pests Out of Your Home

This blog was written by a member of the Flex Seal Editorial Team. All photos by Flex Seal Studios.

If you want to keep pests like mice and insects out of your home, preventative maintenance is key. Small gaps, cracks, and openings around your home can serve as easy entry points for unwanted critters. Fortunately, Flex Seal products offer effective, long-lasting solutions to seal these vulnerable areas while maintaining structural integrity.

In this blog, we’ll show you how to identify common pest entry points and seal them effectively with Flex Seal products.

Note: Before using Flex Seal products, read all directions carefully and take proper precautions, such as being in a well-ventilated area and wearing protective gear while applying.

Seal Gaps Around Windows and Doors

Tiny gaps around windows and door frames are common access points for pests. Over time, weather and structural shifts can cause these gaps to widen, making it easier for insects and small rodents to squeeze through.

How to Seal:

1. Clean the Area: Remove dirt, debris, and any old caulking around the frames. A clean surface ensures better adhesion.

2. Apply Flex Caulk: Apply a continuous bead of Flex Caulk along the edges of windows and doors. Then, smooth the product out using a gloved finger or caulking tool. Make sure to press it deep into any cracks to create an airtight, waterproof seal.

3. Let It Cure: Allow 24-48 hours for Flex Caulk to fully cure.

Flexpert Tip: For maximum pest prevention, pair Flex Caulk with weather-stripping around the moving parts of doors and windows. This ensures that doors and windows remain operable.

Seal Cracks in Foundations and Basements

Mice can squeeze through openings as small as a dime, and cracks in your foundation or basement walls are prime entry points. These cracks also allow moisture in, creating an environment that attracts pests.

How to Seal:

1. Prepare the Surface: Clean the cracks of dust or loose debris. A clean surface helps improve Flex Paste’s adhesion.

2. Apply Flex Paste: For wider cracks, use a putty knife to press the paste deep into the crevice, smoothing the surface for an even finish. For narrow cracks, push Flex Paste directly into the opening. If you have applications in hard-to-reach areas that require pinpoint accuracy, try using Flex Paste in a cartridge.

3. Build in Layers: For large cracks, apply the paste in layers no thicker than ¼ inch, allowing each layer to dry before adding the next for a durable, long-lasting seal.

Flexpert Tip: Focus on sealing exterior foundation cracks whenever possible, as this prevents moisture from entering the structure and creating hidden nesting spots. If exterior access is difficult, consult a waterproofing professional.

Seal Around Pipes, Vents, and Utility Openings

Gaps around plumbing pipes, HVAC vents, and electrical conduits are common. These small openings can also allow drafts, which may increase energy costs.

How to Seal:

1. Inspect and Clean: Check around all pipes and vents, both inside and outside your home. Clean the surfaces to remove any grease, dust, or old sealant.

2. Apply Flex Paste or Caulk: Use Flex Paste in a cartridge or Flex Caulk to seal hard-to-reach gaps around pipes and vents. Smooth it out with a gloved finger or tool for a tight, clean seal. For large gaps or holes, you may want to use Flex Paste in our stay-fresh container.

3. Allow Product to Dry: Depending on the thickness of the layer, Flex Paste and Flex caulk need about 24-48 hours to fully cure. Temperature and humidity will also impact the curing process. The product will cure faster in humid environments than in dry environments.

Flexpert Tip: For exterior walls, seal both the outside and inside of the wall around the pipe or vent. This double-layered approach reduces the chance of pests finding hidden pathways into your home.

Secure Crawl Spaces and Basement Windows

Crawl spaces and basement windows are vulnerable areas where small gaps can lead to infestations.

How to Seal:

1. Inspect for Gaps: Check for visible cracks or openings around basement window frames and crawl space access points.

2. Apply Flex Caulk: Apply a bead of Flex Caulk around the edges, pressing it into any gaps. Smooth the surface for a neat finish.

3. For Larger Gaps (Optional): Take a putty knife and apply Flex Paste in the stay-fresh container. Pack the product deep to ensure a tight seal.

Flexpert Tip: If sealing around windows that still need to function, use weather-stripping for the moving parts and Flex Caulk for the fixed seams to maintain operability without compromising pest control.

Reinforce Rooflines, Soffits, and Attic Vents

Rodents and insects are surprisingly good climbers, often finding their way into attics through gaps in rooflines, soffits, and vents.

How to Seal:

1. Inspect the Roofline: Look for cracks or holes around soffits, fascia boards, and attic vents.

2. Apply Flex Paste: Seal small cracks and seams with Flex Paste, ensuring the material is pressed firmly into the gaps.

3. Coat with Flex Seal Spray: After the paste has dried, apply Flex Seal Spray to create an additional waterproof, flexible barrier.

Flexpert Tip: Use a long-handled applicator to safely reach high areas without climbing on the roof. Always prioritize safety when working at heights.

General Maintenance Tips for Long-Lasting Pest Prevention

Regular Inspections: Check vulnerable areas seasonally, especially after extreme weather events.
Reapply as Needed: Environmental exposure can sometimes cause areas to wear down over time. Reapply Flex Paste or Flex Seal Spray when needed.
Store Leftover Products Properly: All Flex Seal Products should be stored in a cool, dry place to maintain product quality. Flex Paste’s Stay Fresh packaging allows you to reseal the container for future touch-ups.

The Flex Seal Family of Products provides an easy-to-use, durable DIY solution for sealing your home against pests. Whether you’re addressing foundation cracks, sealing around windows, or reinforcing attic vents, these super-strong sealants and adhesives work together to create a durable, weather-resistant barrier.

Ready to pest-proof your home? Check out our products page to get started!