# Safely block rodents - air gap around chimney



## Javik (May 29, 2012)

We had a chimney fire in 2010. Fortunately the two-story house with basement did not burn down, but there was much smoke and water damage trying to put out the chimney fire.

The old chimney in the center of the house had to be removed and replaced, and the house structure was modified so that there is now something like a 3-4 inch air gap all the way around the chimney, from basement to ceiling.

Well after moving in, this last summer of 2011, I heard critters up in the attic. There was a mouse on the 2nd floor which was chewing on stuff, which never happened in the past.

Now in the middle of winter, at night I can hear rustling and chewing in the walls of my 2nd floor bedroom, likely climbing down coaxial cables in the walls that we installed when the house was repaired. It's driving me nuts.

From looking around on the 'net it appears mice can easily climb brick, concrete and bare wooden studs. Well due to the way the new chimney was installed the mice basically have an expressway from the basement to the attic. (I already know the basement is a problem area but I would like to prevent the house from having them roam everywhere.)

How can I stop mice from being able to climb the chimney from the basement BUT also not block the air gap that was put in for safety?


One option appears to be several layers of steel mesh window screen with 1/8" grid holes, bridging the gap from the chimney to the basement ceiling. Mice would not get through that plus it is hard for them to chew steel.

Another option appears to be solid sheet metal steel flashing around the chimney, though this blocks off the air gap completely. I do not know if this compromises the safety function of what the air gap was trying to accomplish.
I can't find anything on the 'net about how to block off this air gap around the chimney and still have everything pass fire safety codes.


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## Gary in WA (Mar 11, 2009)

Page 19/40; http://apps1.eere.energy.gov/buildings/publications/pdfs/building_america/ba_airsealing_report.pdf

Gary


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