Answers to questions about RV Repair and Maintenance from RV expert Dave Solberg, author of the RV Handbook and the managing editor of the RV Repair Club. This column appears Monday through Saturday in the RV Travel and RV Daily Tips newsletters. (Sign up for an email reminder for each new issue if you do not already receive one.) Today Dave discusses devices that repel rodents.
Dear Dave,
We have rodents in the engine compartment and wonder if you have ever heard of or used Grid Guard or RatMat. —Linda

Dear Linda,
I have not used Grid Guard or RatMat to repel rodents, but did a little research and found that both products use a series of interlocking mats similar to tiles available for garage floor covering that are electrically charged with low voltage to deter rodents. They need to have either an electrical source to provide the mild shock or a battery bank.
They are very expensive as you need a system large enough to surround the entire coach. That will cost you $2,400 and up.
I see no testimonials about the products for RV use and have never seen these products at any RV show or dealership. So I am a little skeptical about putting that much money into something that looks like it’s designed for residential and some commercial applications. Also, what happens when you travel in your rig to campgrounds and other locations and can’t take the pads with you? Rodents can crawl up into your rig and remain there for weeks or longer.
The first thing I would suggest is to inspect your rig and seal areas that rodents can enter. That is always the best way to keep critters out of the “house” part of your RV.
Options for rodent deterrent
We have tested several options for rodent deterrent during storage such as dryer sheets, moth balls, and traps. My parents used moth balls in their rig for 10 years and never had a rodent inside. I’m not sure if it was because they stored the rig in a huge gravel parking lot and might not have had many mice during cold weather seeking shelter. All I know is that every spring it smelled like my grandma’s house on the farm when I was young!
The best thing you can do to keep rodents away is remove all food and supplies from your RV before the unit is stored, and to seal all openings. Videos are available showing various traps, baits and such if you are interested.
One product that actually guarantees no rodents for a year is Mouse Free which you spray on the undercarriage. It’s environmentally friendly and utilizes a mint-based product that rodents cannot stand. We have not tested the product; however, it’s been on the RV market for several years and has some great testimonials. Be warned, it is not inexpensive.
Yesterday’s post: Winterizing the RV’s water system
Read more from Dave here.
Dave Solberg worked at Winnebago for 15 years developing the dealer training program, as marketing manager, and conducting shows. He has developed several RV dealer training programs, the RV Safety Training program for The Recreation Vehicle Safety and Education Foundation, and the accredited RV Driving Safety program being conducted at rallies and shows around the country. Dave is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club.
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We live in the mountains of WV in the forest. I liberally put tea bags throughout our coach, drawers, cabinets, in the basement compartments, etc. As yet we have been mouse free since 2017.
We see people with their engine hoods up all the time. One guy told me it was to keep rodents out of the engine compartment,
When pack rats built a nest in my engine compartment within two days of setting up camp, a nearby local brought over some good old fashioned anti-freeze. We put a small cup of it on the top of the engine – and it apparently killed the offending rodents because they were GONE. “They say” you can’t (or shouldn’t) do this if you have pets around.
Browse Shawn Woods Mouse Monday on Youtube. He debunks all sorts of claims.
Ditto on Shawn Woods. Mint oil does repel mice in his video’s. Not sure about Pack Rats or other rodents.
I’ve used Mouse-Free for approximately 4 years now, Yes, it is expensive (around $100 a gallon ) but it does seem to work. I apply it after the summer camping season, prior to storage. I will say that I don’t spray the whole undercarriage as they recommend, but I spray EVERY single water line, drain pipe, electrical line that goes through the floor. Anyplace that something went through the floor, I spray. I also spray around the perimeters of storage bays. So far, so good and I’ve been using way less than a gallon per year.
I’ve used ‘Fresh Cab’ for a long time, still an occasional mouse in the ever present trap but nothing like it used to be.
For the engine compartment, best advice I’ve received is light. Leave the hood open of possible and/or use solar rechargeable string led lights in there. When at Qsite you’ll see many, many rigs with solar led lights laid out under the engine area or around the rig. They are usually not so bright as to bother others but seem to keep pack rats and other rodents away.
Mothballs are extremely dangerous.
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/mothballs-in-gardens.htm
We used Mouse Free on the underside of our 34’ Coachman a few years ago and it did the trick! The upside of course was the end of mice in RV but downside was that it left a rather slippery brown residue that if touching or working under motorhome got on your hands and clothes. Assuming that mice couldn’t get traction and was part of the deterrent.
I guess you could buy a 35lb bucket of grease and coat the areas in contact with the ground and keep them out with that. Our property butts up next to a farm field and I thought I would have a mice problem, but none so far. Of course that may be because we leave for a warmer climate before winter, this year will be different as we don’t plan on leaving until after Christmas.