I cannot even come close to telling you how many times we have responded to complaints of “noises in the attic”. “It can’t be rats, I fixed the whole darn house, they cannot get in anywhere” most will tell us.
I never argue, I politely nod my head as if in agreement and explain that we will be back shortly after our rodent inspection. We head straight for the A/C inline set cover, you know, that metal shroud that covers those ugly A/C lines that climb your exterior walls and usually enter through the attic. We always find two issues with this area of possible rodent entry. It will be completely open for ease of rodent access or we find giant ugly yellowish “globes” of hardened expandable foam hanging unceremoniously from the bottom of the cover.
Expanding foam is a truly wonderful item that has so many great uses, but rodent exclusion is definitely not one of them! While some substances will slow the egress of rodents and others may stop rodents in their tracks…expandable foam is a substance that is easily penetrated for any determined rodent.
Look at these rat chompers, they can chew through wood…expanding foam is of no problem from them.
Of course, to prove my point, I took a few pictures of the rodent rampage on expandable foam.
The foam is not hanging down half as bad as most of the handyman attempts for rodent control.
Here is a worms eye view of the rodent damaged expandable foam.
Another closer look, I took the picture, just figured that I may as well use it.
There are many materials that can be used successfully for rodent control. Your best option is to hire a professional. Try saving a few dollars by doing it yourself and it will usually cost more in the end, especially in areas that requires an expert. The A/C line set cover is only one area that your average do it your-selfer can easily do incorrectly.