Thursday, June 1, 2023


Don’t forget to take care of your RV’s frame

By Chris Dougherty

As advanced as today’s RVs are, one thing that seems to be overlooked by many manufacturers is the finish of the frame. But even if the RV had a great paint job on the undercarriage, it would still need some care from time to time to protect it for the long run.

Think about it… the RV frame is exposed to a rough environment almost all of the time. It is usually moist, dirty, and having all kinds of road debris being chucked at it.

Most RV frames I see have some level of rust. I have seen brand-new ones on the lot with rust. So, it goes without saying that trying to keep that rust away will help give your RV a longer life, and it will look better and be easier to service as well. Now, as a side note, there are lightweight RVs that have frames without paint at all, but they won’t rust as a rule. If you’re not sure, check with your dealer or the manufacturer.

If you have a newer unit with a small amount of surface rust, there’s not much prep work you’ll have to do. You’ll want to make sure the painting surface is reasonably clean, and go to work. But, if you have an older unit that hasn’t had much attention, and the paint is scaling with more severe rust, that must be cleaned up prior to painting. All the loose paint and rust should be scraped off, then the steel primed and painted.

As far as the type of paint to use, I recommend using a rust preventive spray or brush paint such as Rustoleum or Ace Rust Stop or equivalent. They have primers, and I use a gloss black paint. Make sure you cover all areas and apply at least a couple of coats.

Prep for painting a clean surface, including one you have removed rust and scaling paint from, includes a few steps. First, as a safety measure, make sure that any flame-producing appliance is off before painting. MASK WELL – especially if spray painting. You’d be surprised how paint mist travels! This is aesthetic, so don’t worry about stuff under the RV as much as the painted siding, etc. Do a section at a time, and be thorough and complete. If you get it right, you probably won’t have to paint again for a long time.

If you have the equipment, using a compressed air sprayer can make the job easier, but it is messy and really requires some training and the use of proper safety equipment such as a respirator. But, if you have a large RV, it can be a real time saver, and the outcome is usually a little prettier.

On my own coach, I have done a couple of other things while I’m under there. First, I redo each of the chassis grounds. On trailers, there’s probably only a couple, but there are a bunch on a motorhome. I clean the terminals completely, reattach and coat with undercoating.

Another thing I like to do is maintain the step carefully, especially if it is an electric model. I like to make sure it’s rust-free, and well painted with a good tread. I make sure it remains well lubricated and all the attachments are tight.

Painting under the RV gives you the opportunity to also look around for any other damage or problems. Sometimes things will be knocked loose or otherwise damaged while driving down the road. I have seen several RVs whose floors had been chewed through by rodents’ intent on making a nest inside. Finding these, and sealing them up, is essential… but that’s another article. But at the least, you’ll be keeping your RV looking new much longer, and helping to prevent premature failure of your frame.

Chris Dougherty wrote this when he was the technical editor of He is currently the technical editor of Trailer Life and Motorhomes magazines.


Chuck Woodbury
Chuck Woodbury
I'm the founder and publisher of I've been a writer and publisher for most of my adult life, and spent a total of at least a half-dozen years of that time traveling the USA and Canada in a motorhome.


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2 years ago

I use Rustoleum Bright Galvanizing #7584 and also Stainless Steel #7519. Be sure to clean up as best you can first – laying on your back with limited arm space to move around. Both of these products hold up well. Also, if you have a spare tire-wheel hanging underneath check it out for rust and consider spraying it too. Be sure to wear suitable eye protection and a face mask – a lot of what goes up comes down in fine particles!

As a side note – while under there you might add some ID to your catalytic converter – if you have an engraving tool – add the serial number or the VIN number or both – and paint a mark on it with “High Temperature” paint – capable of 1,200 to 2,000 deg’s. F.. Converters are a hot item (pun intended) for theft because of the exotic metals inside. (Your local police Dept. may do it free!)

Tom Carsten
3 years ago

Chris Dougherty’s article on maintaining your RV frame is good advice. Crawling under your rig and painting all exposed metal surfaces is a major task but, to me, worth protecting my investment. A couple of suggestions are to purchase disposable painter’s coveralls since you will undoubtedly bump up against wet paint surfaces and have drips to contend with. I also opted to invest in a higher quality product for greater longevity and rust conversion / encapsulation. I have had great results with Eastwood’s Black Rust Encapsulation (matte black). It took 1-1/2 quarts to do my 36′ motorhome chassis and body supporting framework. It also works great on hitch receivers that are prone to rusting from use and safety chain / cable attachment points.

Bob P
2 years ago
Reply to  Tom Carsten

Just a note, if you bought your RV as an investment you’ve been fooled. RVs are losing money every day you own it. Just as a boat is a hole in the water you throw money into, a RV is a whole in the road you throw money into that you’ll never see again, but ain’t it fun. Just had to comment on your statement about an “investment “ sorry if it offended you.

Al Kemp
2 years ago
Reply to  Bob P

“Investment.” One word 2 meanings.
the action or process of investing money for profit or material result.” I am with Tom on this one.

Gordy B
2 years ago
Reply to  Bob P

I would have to disagree. It is an investment in your future place to stay (especially if you are full time) the more you take care of this “investment” the longer it will last and hopefully give you happy memories. It would not normally be the type of investment you would expect to make money on. Of course the better care taken of this investment, the higher the resale value when the comes to sell. Happy Trails.

3 years ago

If you’re not going to paint, you should power wash the chassis from time to time-especially if you’ve driven through snow and mud. Debris is hard on rubber and nylon parts- like bushings. Keeping springs clean will also help prevent squeaks.

3 years ago

I get my motorhome treated with Krown rust control every year. Keeps the complete chassis in tip top shape.

2 years ago
Reply to  Dave

Being this is a pleasure investment not a monetary investment then WHY not the manufactures offer long term Rust Protection Coating not just paint as the coating products used in pickup boxes as they could offer as an option and let the future buyer decide if he/she want to protect their investment for long term..Manufactures offer a long list of options but none that I know have to protect the framework..shame on the manufactures as these is additional income for those of us who care for our pleasure investments..wake up folks and demand a coating for your investment.. I am looking at a new Grand Design trailer and will demand the frame be coated with a quality product or no deal..

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