Given the microscopic size of many bugs, it's not hard to believe that they can enter the home through cracks or holes that are nearly invisible to the homeowner. That's why sealing cracks on your home's exterior can be one of the best ways to bug-proof your home. One good guideline to keep in mind is this: If a pencil can slide into a crack or gap, a young mouse can also fit through, as can an endless stream of insects.
Start by examining the exterior of your home with a critical eye. Look for damaged or missing sections of siding, cracks in foundations, loose or crumbling brick and rotted wood. You'll be surprised by just how open and inviting your home is when you pay attention to the number of openings you find.
To keep bugs out, use mortar or cement to patch foundations and masonry walls. Clear away damaged bricks and add new ones, filling the joints with mortar. Replace rotting wood or trim, and repair or replace damaged sections of siding or cladding. Consider adding a layer of cementitious backerboard to areas susceptible to termite damage, including exposed foam insulation or wood sheathing. Pay particular attention to the roof line, where bees and wasps frequently build nests. Gaps or holes in the fascia board or soffit can lead to a dangerous encounter with a stinging insect in your home [source: Amundsen].
To really seal your home and repair small cracks, take time to enjoy the wondrous properties of caulk. Caulk is cheap, easy to apply and can go a long way towards keeping bugs out. Add caulk around window frames, as well as around any air intake or exhaust grilles. Use caulk to patch small cracks in foundations and siding, or use it to seal joints where the siding meets the roof or foundation. Latex varieties are best if you plan to paint over them, while clear silicone caulk is more flexible and less likely to dry out and crack over time [source: Gouge et al].