Monday, October 29, 2012

Read it and weep hole

Sometimes I don't take my own advice as quickly as I ought to.  And sometimes I just need one walloping cold front to appear before I can motivate myself to get outside and do it.

Such was the case this weekend when our lovely cool weather inspired me to both gut and scrub the garage following our discovery of mice inside my husband's antique car restoration project (and we are still jonesing for some of Walnut Pointe's reportedly excessive selection of outdoor cats... apparently nobody has sent any our way yet). 

Along with the remedial effort, there's the issue of how to keep mice out in the future.  It's no good simply cleaning up after them - you have to make sure that their food and shelter supply chains are broken. 

The most important measure is to ensure that no food is available on or near the premises, as I explained in this post from just about a year ago.  We never (ever) leave dog food out, and I don't believe that any of my neighbors do either, so I'm not sure what the attraction is (or was) to our particular house at this time, but let me not digress.

The second measure is to create a condition in which there is no shelter available to them.  You have to close off all entry points to the house and garage.  This is much more difficult than it sounds.  Reportedly, mice can squeeze through any opening in the house that is dime-sized or larger.  Rats can enter via a quarter-sized hole or larger. 
Yer gonna need one of these for this next investigative task.
I don't know if the mice got under the garage door or got into the house some other way and then migrated from there into the garage, but I'm not taking any chances.  Every potential gap in the house needs to be sealed. 

The usual limitation applies here:  I am not a licensed exterminator and this blog post is not a substitute for professional advice.  This is simply an anecdotal description of my own situation, and only a partial description at that.  Rodents can do tremendous damage to your house if not properly managed.  Get a professional opinion for your particular situation. 

One of the biggest potential rodent entry points is that both-blessing-and-curse, slab-on-grade creation known as the weep hole
When I bought my first house many years ago, I was horrified to see holes all along the base of the brick work!!  I thought it was just the product of sloppy brick-laying and didn't understand until a neighbor explained to me that these were intentionally included and are necessary for ventilation.  Screengrab of a weep hole from Wikipedia.
Weep holes are essential for allowing the brick facade on your house to "breathe".  As I understand it, if moisture gets trapped behind the walls, it may cause the framing studs to rot.  For this reason, you have to leave them open to the air, but if they are too wide, they can also let small rodents into the house.
Done properly, most of them should be fairly narrow, such as this one...
...but every once in a while, depending on the skill of the original mason and the configuration of your brick-work, you might see one that looks more like this.  Talk about a red-carpet invitation to little critters.  Might as well hang a miniature "Home Sweet Home" sign above it. 
If you check your house carefully, you might see those wider ones around ornamental brick-work areas in particular, perhaps at the base of columns or decorative bump-outs - the types of areas where the fixed size of the bricks wasn't quite right for the design, but the mason opted not to take all the extra time needed to trim the bricks to fit the geometry more precisely, thereby leaving larger weep holes. 

Given that air flow must not be impeded, one of the approaches for dealing with these is to loosely stuff them with copper wool.
You can buy it at pest management stores or online.  This particular product is actually called Stuff-Fit, with the name eluding to the intended usage. 
This kind of copper mesh is advertized as having the following advantages:
  1. It's chew-proof (or at least chew-resistant).
  2. It's loosely woven so it still allows air to flow through it.
  3. It won't rust and stain the side of your house like a steel product would.
Copper wool in abstracto
Quite pretty, isn't it??
This stuff is advertized for use in weep holes, for scorpions as well as mouse exclusion (I lived for three years in Austin, so I am way too familiar with the issue of scorpions getting into the house!), but I didn't find much detail on how much to stuff into any given weephole.   For that, I had to default to common sense: the point is to continue to allow the air through while stopping pests from entering. 
When I stuck my finger into the larger open weepholes, it felt cool, apparently because air was being sucked past it as it was convecting up the inside of the wall.  I cut about an inch of the copper mesh spool and crammed that loosely in the hole, distributing it across the depth of the brick (avoiding a huge tight plug near the front of the facade). 
A finger placed just inside the hole still felt cool, suggesting that air was still moving well across the now-stuffed area.
And by the way, while you're at it, make sure that all of your foundation plantings are cut back from the side of the house.  Many exterminators have told me that plants impinging on the house encourages termites as well as ants.  You can't keep an eye on the condition of weep holes if they are visually blocked like this.  And cutting the shrubs back also promotes better air flow in the area. 
So there you have Part 1 of the "hunt for holes".  I still have to figure out whether or not my garage door bottom seal needs to be fortified, but I will save that for another day.   In the mean time, I'll leave you with this informative vid from Houston's local ABC affiliate KTRK (let's see if I can get this embed code to work). 

1 comment:

  1. The Walnut Pointe cats are still enjoying the high-life around here, if the dove carcass I found in my backyard over the weekend is any indication, and would probably be reluctant towards any re-location attempts. sigh.


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