Squirrels are intelligent, persistent, and agile adversaries. They can climb a vertical brick face, scale a vertical aluminum-sided house, or run up a gutter spout as easily as climbing a tree, and they can run along over or underhanded on utility wires just as effortlessly. To keep them out:

• Inspect your home or building for any possible entrances.
• Screen all attic vents on the inside with hardware cloth. Use ¼″ or ½″ mesh hardware cloth or sheet metal, and extend patches at least 6″ beyond the hole.
• Install chimney, stove pipe and vent pipe caps.
• Repair any damaged trim, shingles or loose roofing.
• Fill foundation cracks and block entrances to crawl spaces.
• Install gutter guards.
• Trim branches hanging over buildings.