6 Best RV Roof Cleaners Before Coating Nomads Swear By

You’ve spent the money on a top-tier RV roof coating and cleared a weekend for the job, picturing a pristine, waterproof seal that will last for years. But the success of that expensive liquid rubber has almost nothing to do with how you apply it. The entire project hinges on what you do in the hours before you even open the can.

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Why Proper Roof Prep is Key to Coating

A roof coating is essentially a thick, specialized paint. Like any paint, it needs a clean, stable surface to grab onto. Your RV roof is constantly shedding its top layer (that chalky white stuff), collecting dirt, and accumulating oils from tree sap and road grime.

Think of it like trying to put a sticker on a dusty, greasy surface. It won’t stick. A new coating applied over that contamination will just bond to the dirt, not the roof membrane itself. The first time the temperature changes dramatically, that coating will start to peel and bubble, and you’ll be right back where you started, only with a much bigger mess to fix.

This isn’t just about performance; it’s about protecting your investment of time and money. A gallon of quality coating can cost over $100, and the job takes hours of hard, physical labor. Taking the time to prep the surface properly is the cheapest insurance you can buy to guarantee all that effort isn’t wasted. A meticulously cleaned roof is the foundation for a long-lasting, leak-free seal.

Dicor RP-RC-1GL: The Industry Standard Prep

When you think of RV roofs, you probably think of Dicor. They are the dominant name in the industry for a reason, and their two-part roof preparation system is the textbook example of how to do it right. This isn’t just a cleaner; it’s a dedicated surface preparation treatment.

The first part is the cleaner, which is designed to strip away wax, oils, and embedded dirt. The second part, the "Activator," is what sets it apart. It’s a chemical agent that essentially micro-etches the surface of the EPDM or TPO membrane, creating a more porous and receptive surface for their coating to mechanically bond to.

The main consideration here is system synergy. If you’re using a Dicor brand coating, using their specific prep cleaner is a no-brainer. It eliminates any guesswork and ensures you are following the manufacturer’s exact recommendations for maximum adhesion. While it might seem like an extra expense and step, it’s a small price for the peace of mind that comes from knowing you did the job exactly as the chemists intended.

Thetford Rubber Roof Cleaner & Conditioner

Thetford is another trusted name you’ll see in any RV supply aisle. Their Rubber Roof Cleaner & Conditioner is a fantastic product that straddles the line between routine maintenance and pre-coating preparation. It’s a bit less aggressive than dedicated prep solutions, which can be a good thing for older, more delicate roof membranes.

This product is formulated to remove the tough grime and oxidation you need to get rid of before coating. It also contains a conditioner with UV-blocking agents. While the conditioning aspect is irrelevant when you’re about to cover it with a new coating, it speaks to the product’s gentle nature. It cleans effectively without harshly stripping the material.

Choose Thetford if your roof is in decent shape but needs a thorough, deep cleaning. It’s a great option if you want to buy one product that can serve as both your pre-coat cleaner and your go-to for annual roof washing afterward. You may need a bit more elbow grease to remove heavy chalking compared to a more potent stripper, but its performance is reliable and safe.

Simple Green Pro HD for Heavy-Duty Cleaning

Don’t confuse this with the classic green stuff under your sink. Simple Green Pro HD is a purple, heavy-duty cleaner and degreaser specifically formulated to be non-corrosive and safe on surfaces like aluminum, which is critical for RVs. This is the product you bring in when the roof has been seriously neglected.

If you’ve just acquired a used rig with a roof that’s black with mildew, caked in tree sap, and stained from years of sitting, this is your starting point. It’s a concentrate, so you can custom-mix its strength to match the severity of the job. It excels at cutting through the greasy, oily road film and biological growth that other cleaners struggle with.

The power of this cleaner comes with a critical responsibility: you must rinse it meticulously. As a degreaser, any residue left behind will act as a bond-breaker for your new coating. This isn’t a "rinse and go" product. You need to wash, scrub, and then rinse repeatedly until the water running off the sides is perfectly clear and free of any suds. It’s a powerful tool, but it demands a thorough process.

EPDM Coatings Pro-Clean Roof Prep Cleaner

This one is for the specialists. EPDM Coatings is the company behind popular products like Liquid Roof and Liquid Rubber, which are true liquid EPDM coatings. If you’ve chosen to use one of their high-performance products, it only makes sense to use the cleaner they designed to work with it.

Pro-Clean Roof Prep is engineered to target and eliminate the worst enemies of coating adhesion: silicones, waxes, oils, and grease. Many RV owners use silicone-based sealants or polishes containing silicone, which leaves an invisible film that is notoriously difficult for coatings to stick to. This cleaner is formulated to remove that film effectively.

Making the decision here is simple. If you’re using an EPDM Coatings product, use their cleaner. You’re not just washing off dirt; you’re creating the specific surface profile their coating chemistry is designed to bond with. Using a different cleaner might work, but it introduces a variable that could compromise the result. Stick with the system.

Camco Pro-Tec: A Trusted RV Roof Cleaner

Camco products are everywhere in the RV world, from sewer hoses to leveling blocks, and their Pro-Tec RV Roof Cleaner is a solid, reliable choice. It’s a purpose-built formula that’s widely available and has a long track record of getting the job done without any fuss.

Pro-Tec is particularly effective at lifting and removing the chalky oxidation that forms on EPDM roofs as they age. It’s a biodegradable formula that’s strong enough to deep clean but gentle enough that it won’t harm the roof membrane or the RV’s sidewalls as it runs off. It strikes a great balance between power and safety.

Think of Camco Pro-Tec as the dependable workhorse. It’s not a specialty degreaser or a chemical activator, but it’s a fantastic all-around pre-coat cleaner for a roof that’s been reasonably maintained. If you need to get your roof from "kind of dirty" to "squeaky clean and ready for coating," this is a safe and effective bet.

Spic and Span for a Residue-Free Surface

Sometimes the old ways are the best ways. For decades, a legion of seasoned RVers have sworn by a simple, cheap, and incredibly effective product for roof prep: powdered Spic and Span. It’s a classic choice for a very specific and important reason.

The magic of powdered Spic and Span is what it doesn’t have. Unlike many modern liquid cleaners, it contains no softeners, scents, or additives that can leave behind a residue. Its job is to clean, and it rinses away completely, leaving a perfectly neutral surface for your coating to adhere to. This residue-free quality is the holy grail of pre-coat cleaning.

To be clear, you must use the powdered formula, not the liquid version. Mix it with water according to the box directions, scrub your roof in sections with a medium-bristle brush, and rinse thoroughly. It’s a simple, no-frills approach that delivers a surgically clean surface that many expensive, specialized cleaners struggle to achieve. It requires more manual effort, but the results speak for themselves.

Final Rinse: The Most Critical Pre-Coat Step

You can use the most expensive, scientifically-formulated cleaner on this list, but if you fail at this last step, the entire job is compromised. The final rinse is not just about getting the soap off; it’s about returning the roof to a completely neutral state, free of any foreign contaminants.

Your process should be methodical. Rinse the entire roof until you no longer see any visible suds. Then, get your brush out again and lightly agitate the surface in a small area while running water over it. If you see even the slightest hint of new bubbles or foam, there is still cleaner residue present. You must continue rinsing until you can scrub any part of the roof and see only clear water running off.

This step cannot be rushed. That final, lingering, invisible film of cleaner is just as effective at preventing adhesion as the dirt you just washed away. Give it an extra 15 minutes. Let the roof dry completely, and then do one last "dry" check by wiping a small area with a clean, dark-colored rag. If it comes up clean, you are finally ready to coat. This meticulous finish is what separates a 2-year job from a 10-year solution.

Ultimately, the specific bottle you choose matters less than your commitment to the process. Whether it’s a high-tech system prep or a simple box of Spic and Span, the goal is the same: to create a surgically clean, residue-free surface. That diligence is what ensures your new coating will perform as promised, giving you a leak-free roof and the peace of mind to focus on the road ahead.