keep rodents out of rainscreen system
farmgirl3
| Posted in General Questions on
I am in a very high mouse and vole area and worried about the furring strips behind my future house siding. What is a simple way to keep them out of between furring strips? Will they chew through Coravent? Any experience with XCLUDER mesh? There rodents can get in 1/4 inch hardware cloth.
thank you
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I've never head anyone report a problem with rodents chewing through Cor-a-Vent.
But the very toughest material would probably be perforated brass sheet. Pricey though.
I know people also use stainless steel mesh, like window screen material. Copper mesh works as well and I've heard that it also deters ants and termites, though I don't know that for certain.
Here are links to 2 other comment streams that asked similar questions and got lots of responses.
https://www.greenbuildingadvisor.com/question/rockwool-comfortboard-80-bottom-edge-details
https://www.greenbuildingadvisor.com/question/how-to-protect-the-bottom-of-rockwool-comfortboard
hardware cloth
no reason for anything expensive
farmgirl3,
When rain-screens were first mandated in our building code, most people used insect screen, but soon found it was prone to damage, either by weeds going into the cavity, or pests - and once it is damaged it is very hard to retrofit another solution. Now the most common solution is perforated flashing. All the lumberyards here stock it, but you can also get it made up by a metal shop, or buy it from suppliers like: https://www.menzies-metal.com/metal-flashings/perforated-j-channel-rain-screen-low-back/
I still find it odd that our standard practice here is to use PT furring strips and aluminum screens in direct contact.
"weeds going into the cavity"
This is so true!
This is why I specify on my drawings a 2' wide strip of non-porous clay cap around the perimeter of the foundation and also note that there be no irrigation lines of plants closer than 2' to the wall.
Canda_deck,
I asked a while ago why people are pro furring strips at all given they will at least get wet. I even called furring strips the worst twisty wood you can buy. I was defiantly down on the idea.
I think the majority, if not all, responded non PT will not be damaged. No one recommended PT.
I know that insects will get into tiny little spots just because they can, and birds will look for holes up high to nest in, but mice and rats generally don't just want to chew through solid objects without a reason. That reason can be a food source or a warm place to nest.
Newer cars have been getting a lot of damage from rats and mice because they're attracted to the warm engine and then stay for the yummy soy based insulation on the wiring. Car engines aren't very well air sealed so tough to keep them out.
The house can be inviting if the rat can sniff out an air leak. If the house itself is fairly tight then a simple barrier will suffice as there won't be a flow of air for them to follow. The rain screen will have air movement, but not to the inside of the house where there would be food sources and warmth. Basically, the rain screen isn't an attractive nesting site for rodents to begin with. It's only an issue if there are good open paths to the interior behind it.
andy_,
"mice and rats generally don't just want to chew through solid objects without a reason."
That's been my experience too. I still wouldn't rely on insect screen on the bottom of the cavity though.
Totally. I think we just need to shoot for a good middle ground between Fort Knox and insect screen.
I've used a wire mesh backed with a kevlar insect screen intended for catios. If it can stand up to cats trying to claw their way out it should be ok for rats trying to chew their way in.
When the gap is narrow enough to preclude rodents I just use the screen.
I doubt rainscreen cavities are great places for rodents to nest. There is airflow and moisture and no heat or food.
That said, I have wrapped cor-a-vent with 4 in wide stainless steel mesh. Runs $30-35 for a 50 ft roll. I made a series of progressive die’s out of scrap 3/4 ply and pulled the mesh through to get a tight shape around the Cor-A-Vent. The drawback with this method is it does make the strip thicker than the other battens so it makes it harder to plane out some siding types.
Spenceday,
"There is airflow and moisture and no heat or food."
I've found rats nesting in the very small space between the ridge cap and sheathing on a metal roof, and under the riser above a septic tank lid. I'd rather detail the exterior to exclude them than rely on their choices of whether a space is a good habitat.
If you can't find the perforated flashing, you could just as easily find "punched" or perforated bar stock steel at the big stores in the correct width and attach to the exposed edge. If you are against buying or making an aluminum option.
I used quickmesh stuffed with stainless steel wool. this provides both rodent/insect protection and a degree of spark arrestor... It is cheaper than coravent
1st pict: subslab insulation flashing
2nd pict: 2" mineral wool install
3rd Pict; furring strips
4th pict; (hard to see.. I had to zoom way in... 4" wide quickmesh slides under mineral wool and furring strips and is folded up over furring strips. This creates a 2" deep mesh pocket which I stuffed with Stainless steel wool.) Its not clear in this picture, but the mesh actually fold ups and is stapled to furring strips..
5th pict siding goes on after.
This will run you $51 for 50 LF or a little over a $1 per LF... Where as coravent will run you 2x-3x that... (in material)...