When you're staring with a gap in your rim joist or a gap below your sink plus wondering if will rats eat through spray foam , the short and truthful answer is a resounding yes. It's one of those home improvement myths that will just won't die—the idea that because spray foam expands and hardens into a solid mass, this acts as a few kind of magical hurdle against rodents. Within reality, an identified rat discusses spray foam and sees nothing more compared to a minor inconvenience, or even worse, a comfy bit of insulation to help them construct a nest.
I've seen lots of homeowners spend a weekend sealing up every nook and cranny with all those cans of yellow foam, only in order to find a stack of yellow "snow" on the flooring a few days later. That will dust is the particular remains of the difficult work, chewed straight into oblivion by a rat that wanted to see exactly what was on the other side from the wall.
The reason why spray foam isn't the barrier you believe it is
To comprehend why rats make such quick work of this particular stuff, you have to realize their teeth. A rat's incisors are incredibly strong—we're talking about a 5. 5 on the Mohs scale of mineral hardness. Regarding context, that's tougher than copper plus even some types of iron. They can chew through business lead pipes, wood, aluminium siding, and actually poorly cured concrete if they have a ledge to begin on.
In comparison to a guide pipe, spray foam is basically cotton candies. Whether you're making use of the standard DO-IT-YOURSELF stuff from the big-box store or use the denser, professional-grade closed-cell foam, it's still simply a plastic plastic filled with atmosphere bubbles. It offers zero structural resistance against an animal that needs to get indoors intended for warmth or meals.
They aren't actually "eating" it
When people ask if will rats eat through spray foam , they usually mean "chew through, " but it's worth making clear that rats don't actually eat the particular foam for nourishment. Rats are scavengers, but they aren't stupid. They understand that plastic foam isn't food.
Instead, they gnaw it for two major reasons. First, they need to. A rat's the teeth never stop growing—they grow about five inches a 12 months. When they don't constantly gnaw on things to file all of them down, their tooth would eventually grow into their very own skulls. Second, spray foam often prevents a "run" or a draft they've been following. If a rat smells meals or feels heat coming through the gap you've just sealed, they're heading to chew through whatever is in their particular way to get back to that source.
What regarding "Pest Block" foams?
You've most likely seen the cups of spray foam specifically labeled since "Pest Block" or "Rodent Resistant. " These are usually a different colour, often bright lemon or grey, and they claim to cease pests from breaking through.
Do they work? Well, sort of. But they aren't the silver bullet. These products usually contain bittering agents like denatonium benzoate. The idea is that when the particular rat starts nibbling, it gets a face filled with some thing that tastes totally disgusting, which in theory makes them cease.
Whilst this might deter a casual explorer, a hungry or cold rat is usually incredibly persistent. When they really want to get inside, they'll often just power through the poor taste. Also, once the foam has been exposed to the air for a long period, all those bittering agents may lose their punch. Don't misunderstand me, if you have in order to use foam, the particular pest-resistant stuff is usually a better option than the standard stuff, but don't expect it to hold the queue upon its own.
The issue with using foam as the standalone fix
The biggest problem with relying on spray foam is that it creates a false sense associated with security. You see the hole is usually filled, you don't see light arriving through anymore, and you think, "Job carried out. "
Yet rats are experts of finding the path of least resistance. If you've used foam to seal a hole, you've actually given them an extremely very clear target. They can experience the vibrations and hear the sounds of your home through the foam. Plus, spray foam is an excellent insulator for sound and heat, but it doesn't cease smells. If there's a kitchen on the other hand of that foam, the rat can still smell the particular crackers inside your kitchen.
How you can in fact stop them (The "Sandwich" Method)
If you're deceased set on making use of foam because it's great for ending drafts (which this is), you need to combine it with something which actually hurts to chew up. This is where the old-school strategies come in.
The particular most effective way to utilize foam regarding rodent proofing is definitely to pair this with stainless steel made of wool or even water piping mesh . Standard steel wool works too, but it eventually rusts plus falls apart, especially in damp places like basements or even crawlspaces.
- Stuff the gap: Get a good quantity of copper mesh or stainless steel made of woll and jam this into the opening.
- Secure it: Make use of a screwdriver to pack it within tight so generally there are no gaps.
- Foam over it: Now, spray your foam straight into and over the mesh.
When a rat attempts to chew through this, they'll hit the particular metal. Metal mesh is like shards of glass to a rat's mouth. It gets trapped in their tooth and irritates their own gums. Most rats will give upward almost immediately as soon as they hit a layer of steel or copper. The foam's job right here isn't to prevent the particular rat; it's just to hold the particular mesh in location and seal the particular air leak.
Signs that rats have bypassed your own foam
In the event that you've already covered some holes plus you're worried they didn't hold, there are some telltale signs to look for.
- Foam debris: Look intended for tiny crumbs associated with foam on the floor. If it looks like someone got a cheese grater to your insulation, you've got a guest.
- Grease marks: Rats have greasy fur. When these people squeeze through the tight opening, they leave behind the dark, brownish-grey smudge. If you observe "rub marks" on the edge associated with your spray foam, they're using that will spot as the doorway.
- The "light test": With night, switch off the lights within the space and have somebody shine a bright flashlight from the outside (or vice versa). In case you observe even a pinprick of light through your foam, the rat can likely smell what's inside, and a mouse often will squeeze through.
Better alternatives for serious access points
When you have a big gap, like where a pipe enters the home, spray foam shouldn't even be your first thought. For individuals areas, you're much better off using hardware fabric (a heavy-duty metal mesh) or even page metal.
Hardware cloth with 1/4 inch space is the precious metal standard. You may cut it to size with tin snips, screw this over the opening, and then use a little bit of spray foam or caulk just to seal off the edges intended for weatherproofing. It's the bit more work than just directed a nozzle plus pulling a cause, but it's the particular only way in order to sleep soundly understanding you haven't just built a "rat door. "
It's about more than just one hole
Ultimately, if you're asking will rats eat through spray foam , you're likely dealing with a bigger pest pressure issue. Sealing one particular hole is great, but rats are resourceful. If you block one entrance with foam and nylon uppers, they'll spend the night time circling your base looking for the next weak spot.
You have to look at the whole picture. Are presently there tree branches touching your homes roof? Is presently there pet food still left out on the particular porch? Is your trash can cover loose? Spray foam is just one tiny tool in a much larger battle. Use it for what it's good for—stopping air leaks—but never trust it to stand up to the teeth of a starving rodent. It just isn't built for your fight.