Preventing Squirrels from Entering Your Chimney
If you have a chimney, you could end up having problems with squirrels if it's not capped or screened. Stop these unwelcome pests with a few simple preventive measures, like mesh, screens, chimney caps and squirrel guards. These caps and screens will also stop other animals, like bats, birds and rats, from entering your chimney.
Most commercial chimney caps will do a good job of keeping squirrels from falling directly down into your chimney, but don't block access to the outer flue. The outer flue is an area you can't reach from inside or outside the chimney. It's a space between the inner flue and chimney wall. If a squirrel falls down into this tight space, they can't climb out.
Adapt your cap with a fine enough mesh or screen so this can't happen. For most caps, the addition of some mesh or square chicken wire, screwed or bolted to the flue, will work. To determine if your flue needs additional screens, you can either climb up on the roof and look, or check with your local hardware store or chimney supply store for the model you use.
If there is more than 1/2-inch clearance between the outer and inner flue, buy heavy duty wire mesh or screen and encircle the flue with it. Use metal screws and washers to attach it to your existing flue.