Squirrels can cause considerable damage in the attic. But not always. It depends on many factors, such as the length of time the squirrel(s) have been in the attic, the number of squirrels, the presence of electric wires or water pipes or lack thereof, they type of insulation the personality of the squirrels, and so on. This is why a thorough attic inspection is important. You can get an understanding of what the squirrels have done, and see specifically what damage they may have caused. Look for areas of trampled down insulation, and paths and tunnels in the insulation. Look for squirrel feces and urine stains. You should notice hundreds or thousands of fecal pellets. Often, but not always, squirrels bring nesting material into the attic. It's usually leaves and other plant matter. This is a good place to find a nest of baby squirrels. Look for chewed wood, and play close attention to electric wires, to see if they have been chewed and constitute a fire risk. Squirrels are rodents, and they love to chew, and for some reason are drawn to wires. Also, sometimes squirrels in the attic will die, and keep in mind that a dead squirrel in the attic is another form of "damage", in that it causes a terrible odor and flies! The feces and urine that the squirrels leave behind may cause slight odor problems, but more importantly are a potential source of pathogens or illness. Don't touch them! Waste left behind can also encourage the growth of mold, attract bugs like cockroaches, and contains a pheromone scent that will encourage new squirrels to enter the attic in the future.
Squirrels almost always chew on wood, such as the wood beams in the attic, or wood roof slats, like in the above photo, or wood trim outside, in order to get in.
Squirrels are rodents, and thus they chew all the time to sharpen their teeth. They love to chew on electrical wires for some reason - maybe the soft texture.
This can vary. Some squirrels bring in little to no nesting material, choosing to use the insulation instead. Some bring in huge piles of leaves and debris.
The squirrels will definitely poop and pee in the attic. They leave behind large numbers of droppings and urine spots (and debris like in the above photo).
What kind of damage do squirrels cause in an attic? Squirrels are cute little animals that prance around your yard, but they can be very dangerous and destructive. These creatures not only carry disease, but like to burrow and make a mess of areas they can get into. This means that you can see some serious damage to your home. Squirrels are rodents that need to chew, and they like the texture of wires, or electric wires in the attic. Read more about do squirrels chew on wires in the attic? So what kind of damage can a squirrel cause you may wonder? Well, let us start with the obvious first. Squirrels need to relieve themselves at times and so they will relieve their waste as needed, no matter where that is in your attic. Honestly having squirrel urine and feces in your attic is bad enough in and of itself. That is enough damage on their own, but that waste can have parasites and disease in it that can be terrible for you, your family, and your pets. Plus they can breed and turn your attic into a disaster area for years. This can lead to mold and mildew as well, which can ruin your home. Besides waste products there is the obvious problem of squirrels getting into things. Your insulation is likely to take the biggest beating, because the animals may not only want to use it as bedding, but they will put their waste on that as well. Because disease can spread you may have to replace a large portion of your insulation. If you have boxes of clothes, linen or books, you may find that squirrels have dug into these boxes to get materials out of there that they think would be good for building a nest. Keep in mind that they simply don’t pick out what they want and put everything else back where they found it originally. They tear apart what they want to use, and they tear apart that they don’t care about either. What you wind up with is a big mess, and all your materials may be destroyed as well. Then you have to consider the damage that may occur directly to your home. Squirrels may gnaw on your siding or boarding to make other access points. They may tear apart wiring and covering. They can destroy paint, tear up coverings and make a general destruction of the look and feel of your home. Plus a really persistent squirrel may find a way from the attic down your walls and then you will have a real mess. Also, be aware that if you have squirrels living in your attic, they might die in your attic, and cause a big odor problem. Read about How To Find a Dead Squirrel in the House. Know that if a squirrel has found its way into your attic you have some work ahead of you.