Words: Steven Fechino
Insects and rodents can be a problem depending on where you live in the United States. In the United States we have Carpenter Bees in the spring, honeybees in the summer, Stink Bugs seek warmth and darkness in the fall, Ants are attracted to moisture and spiders like it dark. Rodents that are small like mice can fit through an opening ¼ inch wide or about the size of a penny. Why does this even appear in a Masonry Magazine, because we leave openings in our masonry every day for airflow and drainage that can provide perfect hallways to the cavity for insects and pests. In the United States, there are approximately 70,000 different species of insects, it just takes one species in the cavity of a wall to become problematic.
The insects found around the country may be different based on where you live, but all present the same design considerations, to prevent them from entering through the masonry.
Mortar Net Solutions offers four basic preventative measures that can be used to prevent the infestation of insects. For Cavity wall construction, the first line of defense would be to fill the weep openings with either a CellVent or a WeepVent. The CellVent is a corrugated Plastic, industry standard that has openings small enough to allow water to pass but will prevent critters from entering through the weep opening. The WeepVent, my personal choice, is a structural strand polymer mesh that is random enough that it would again prevent passage of insects to the cavity yet allowing air and moisture to pass freely though the weep opening. Mice could chew the polymer, but history has shown that the weeps being filled with a proper weep vent material serves as a good preventative measure.
If you are placing weeps at the top of the façade either at the shelf angle or the soffit, it is still important to seal the weeps properly. Mice and insects can enter up there too and once they check in, it is tough to get them to check out.
When constructing the cavity wall, the mortar collection can also offer additional pest protection. MortarNet with Insect Barrier offers a superior mortar collection product that has a fabric heat welded to the mesh that is placed against the inside face of the brick at the intersection of the WeepVent. This added protection will allow a second layer of protection to the insect and rodent protection of the building.
For single wythe construction, BlockFlash offers a bug guard in every spout. No sense in allowing the little critters to enter wall through a drainage vent.
Mice often enter the cavity through the masonry openings found on a structure, one of the common openings are the residential brick vents. Originally when placed, the brick vents typically have louvers attached to a hardware cloth usually 1/8-inch by 1/8-inch, of course models differ. Over time it is not unusual for the hardware cloth to separate from the vent allowing passage of rodents, which may become evident in October when the cold temperatures motivate the rodents to find warmer accommodations. Simple late summer home maintence is a good preventative for this.
Louvers found on the gable end of a masonry house, though not readily accessible, also offer a perfect passage for bats, mice, insects and squirrels. If any of these critters enter the attic portion of your house, you may not readily know they are tenants, but over time they can create problems with feces and chewing habits. The best way to keep up with this is to inspect the attic of your house before you are up there getting all of the hundreds of tubs of Christmas decorations that you get to carry down by yourself……need I say more?
Ok, we have discussed the various ways to prevent the insects and rodents from entering the structure, but what about when they are already resident rodents. We all have shops that likely have a mouse nest or two, what next. Mice, for instance, stay nested during the light hours of the day. They do leave the nest at night looking for food. This is when most trapping will actually take place. I am not going to get into the discussion of how to humanely trap and release a mouse, I am going to discuss methods of actual trapping. You have four methods. Poison, not my choice, but you can use a warfin bait to kill the mice. Unfortunately, you cannot ever know where the mouse will die, therefore, if something eats the dead rodent, like a dog or a cat, then it too can die from the warfin poison. The second and third options are to use a Victor Wood Snap Mouse Trap, you know, the kind we all hate to set because it hurts when you are not fast enough, or the glue trap. Either one will be effective. Place the traps against a wall or on a ledge where you may expect the mice to travel, if you are trapping in a building, place the traps where they are out of the way, but accessible for visual inspection. Mice droppings will also indicate activity, placing anywhere in these locations will usually produce removal opportunities.
When cleaning up after the mice have been exterminated, (do not expect complete removal of mice, they typically become a maintenance effort long term), it is important not to breathe the dust, nest, urine from the nests or mice activity. Mice can carry various problems for humans and therefore, though you may never have had a problem in the past, should take precautions when removing mouse residue. Using a 1-part bleach to 9-parts water to spray the mess before removal. It is also not recommended to vacuum the mess up, because the potentially disease-laden residual particles will travel through the blower and make it airborne, which can make you sick. I never thought about this before today, but it makes sense, especially if you have rats to remove in addition to mice.
When bating the mice, do not use Swiss cheese-like they did in the Tom and Jerry cartoon, though it worked in the cartoon, Peanut butter works well, if you use a little too much, it makes take a few visits for the rodent to set the trap, but given time, it works. Hopefully, your mice will not be as smart as Jerry and give you a fit.