Whether it’s summer or winter, new home or old, in urban settings or rural ones, homeowners have to be prepared to fight an unending battle against the forces of invasion.
Mice, spiders, bees, chipmunks, ants, birds, bats — you name it, they’d all like to take up residence in our nice, warm, cozy homes.
Fortunately, setting up a good perimeter defense doesn’t require a moat and a drawbridge. With a weekend or two of effort and a few inexpensive materials, you can fortify your home and put an end to intrusion from a wide variety of common pests.
If these are projects you’d prefer not to tackle on your own, most exterminator companies as well as many smaller contracting companies and home handyman services can take care of them for you.
Most homes have screened vents in several areas to allow for air movement and moisture removal in the attic and crawlspace. The most common locations are in the concrete walls of the foundation, in the eaves or soffits under the roof, and up near the roof’s ridge. There are also likely to be screened vent caps in other areas on the roof, which are the exterior terminus for things such as ventilation fans.
Damage to the screens on any of these vents is a common entry point for critters of all sizes. Birds have been known to peck and tear through screens to reach warm attics for nesting and it only takes a little rip to allow bees and other insects easy access, so you’ll want to begin with a careful inventory of all the screened openings.
Pay particular attention to areas where dryer vents or exhaust fan vents may have been installed by cutting through the vent screening. These vents can also be tempting access points for people running wires and cables into the crawlspace and attic, so be on the lookout for those penetrations as well.
Hardware stores and home centers carry small rolls of galvanized metal repair screening — be sure and purchase one with the same size mesh as the screen you’re going to repair, and use metal screening, not the fiberglass variety used in window screens.
To make the repair, simply cut a piece of screen about 1/2 to 1 inch larger than the hole. Use tin snips to cut the material and gloves to protect your hands. Carefully un-weave and remove one or two rows of wire at each edge of the patch material, which creates lots of little wire “fingers” at the edges. Weave these fingers into the screen of the vent to hold the patch in place - with a little patience and the help of some needle-nose pliers or even large tweezers, you can patch holes of just about any size.
Cracks and gaps
It doesn’t matter how new or old your house is, they all have cracks and gaps in a variety of places around the perimeter. Some common locations to check and list include blocking between rafters; joints in roof framing; gaps around vents; gaps around doors and windows; foundation cracks; loose masonry; loose, cracked, or gapped siding; the top of foundation and basement walls; around pipe, wiring, and duct penetrations; and around weatherstripping and door sills, including your garage doors.
A careful walk around the outside of the house will usually be enough to discover many of larger, more obvious ones. For the rest, the best way to find them is for one person to shine a bright light around various joints while a second person in the attic or crawlspace searches out the light beams that indicate penetrations.
For your repairs, you’ll need a couple of tubes of latex sealant with silicone (clear, colored or paintable), a caulking gun, a can or two of expanding foam sealant, and some foam backer rods in a couple of diameters. All of these materials can be found at hardware stores and home centers.
First, make sure the gap is clean and secure. Nail or screw down loose boards or fittings, and clean all the gaps thoroughly; you can use an air compressor with an air-gun nozzle, or some canned air of the type used for cleaning electronic equipment (wear eye protection with either method).
For cracks and gaps up to about 1/8 inch wide, the latex silicone sealant and your caulking gun is all you’ll need. For wider cracks, up to about 3/8 inch, fill the crack first by forcing the foam backer rod into the crack with a putty knife or the end of a screwdriver, then apply the sealant to finish the repair.
For cracks and gaps over 3/8 inch, use the expanding foam sealer (be sure to read and follow all of the manufacturer’s instructions and precautions). Mice and other rodents like chipmunks will chew right through the foam, so either before you spray it or as you're spraying it, embed some wire mesh or old window screen in the wet foam. When the foam is dry, the embedded mesh will create an impenetrable barrier if anything tries to chew through.
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