Birds in the Belfry

As a home inspector it is not unusual to find uninvited guest in the home we are inspecting. During a home inspection the inspector will note obvious openings in attics and crawl spaces, but finding all the openings that can make your home accessible to these uninvited guest is not something that is always obvious during a home inspection.
Below is a common question I receive about uninvited guest:

Question:
We live in an older two-story house that we bought ten years ago. Recently we have noticed that we have birds nesting in our attic.
How are they getting in the attic? How can I discourage them from living there, short of buying a cat to go up there?
I feel this is something I can do ourselves if we knew where to start.
If you have any ideas we would appreciate it.


Answer:
It is most likely that they are getting in your attic by way of the attic vents.
The first place I would check is the gable end vents. Theses vents are the openings in the peak on the end of your house. You will see the louvers; window screen covers the back of these louvers. The screening keeps the birds out. Over the years, the screen gets holes in it and the birds get in. From the attic, inspect the screen for holes. Remember a bird can get in a very small hole.
You can patch the hole, but usually it is easier to just staple new screening to the back of the louvers.