Squirrels usually build their nests, known as "dreys", in trees, but they are resourceful & have adapted into human society so are commonly found in both urban & suburban areas.
Your attic / loft / roof space provides a warm home for squirrels with shelter from rain and predators. A hole may need only be as big as the squirrels head for it to gain entry to your roof.
Squirrels will also commonly enter warehouses for shelter and food; they can cause considerable damage to stock.
Squirrels make a considerable amount of noise when nesting in roofs, which can be quite distressing to people. They can cause serious damage when entering a property by tearing up loft insulation for bedding, along with gnawing wood and pipes. Squirrels have also been known to cause fires by chewing things such as electrical wires.
It is important to be a hundred percent sure that all squirrels are removed before proofing measures are taken out. We can remove the squirrels for you, block any access points they can re-enter, and advise you on other preventory measures.