Cleaning a fiberglass RV takes a gentle rinse, pH-neutral soap, soft tools, a thorough rinse, and immediate drying to protect the gel coat and seals.
One wrong cleaner or a dirty mitt can leave permanent hazing, lift decals, or let water into seams. The good news: a fast, methodical wash keeps your RV’s fiberglass panels glossy for years without any specialty gear.
What You Need to Clean Fiberglass
Stick with soft, non-abrasive tools and a neutral soap. Everything else risks dulling the gel coat or damaging seals.
- Soap: pH-neutral RV wash or mild liquid detergent.
- Wash mitt: Microfiber wash mitt or a natural boar’s-hair brush.
- Drying tools: Clean microfiber towels or a leaf blower / air dryer for seams.
- Optional: A separate mitt for tires and lower rocker panels to reduce swirl marks.
Use the two-bucket method (one soapy, one rinse) to keep grit from re-contacting the finish. Avoid dish soap, ammonia, harsh degreasers, and abrasive pads —
How to Wash a Fiberglass RV Correctly
Work from the roof down so dirty water never runs over an already-cleaned section. Close all windows and vents before you start.
- Pre-rinse. Flood the entire rig with a hose or low-pressure spray (1,200 PSI max if using a pressure washer). Knock off loose dirt and wet the surface to soften grime.
- Wash in sections. Dip your mitt in soapy water, clean one panel at a time (roof first, then sides, top to bottom), and rinse that section before moving on. Never let soap dry on the surface — it leaves water spots and a cloudy haze.
- Rinse thoroughly. Use a hose nozzle on a gentle spray pattern. Keep the pressure-washer tip at least 12 inches from the surface and avoid blasting directly at seals, vents, roof edges, decals, or graphics. A misaimed jet lifts decals and forces water into openings.
- Dry immediately. Wipe down flat panels with a clean microfiber towel. Use a leaf blower or air dryer around windows, seams, and badge edges where trapped moisture causes problems. Dry fabric absorbs residue — don’t let the towel drag dirt.
- Inspect and address stains. If black streaks or diesel grime remain, use a fiberglass-specific stain remover after washing, not an abrasive cleaner. For oxidized or faded gel coat, compounding and waxing restores shine — but keep machine polishing to small areas and away from decals.
If you are ready to buy a specialty product, our tested roundup of the best fiberglass camper cleaners covers what works and what wastes money.
Mistakes to Avoid When Cleaning Fiberglass
Most gel-coat damage happens not from weather but from the wrong wash technique. Here are the common errors and their fixes.
- Using dish soap or degreasers. They strip wax, dry out gel coat, and cause chalking. Use only pH-neutral RV wash.
- Scrubbing with abrasive pads, steel wool, or hard bristles. These create micro-scratches that attract dirt and dull the finish. Stick with soft microfiber or boar’s-hair.
- Letting soap or wash water dry on the surface. Even pH-neutral soap leaves a water-spot film if it dries. Rinse and dry each section before moving to the next.
- Neglecting decals, graphics, and seals. Pressure washers and aggressive scrubbing at edges lift graphics. Wash around decals by hand with a light spray pattern.
- Using a dirty mitt across the whole RV. One gritty mitt re-deposits sand and road film over the entire rig. Use a separate bucket for rinsing and separate mitts for lower, dirtier panels.
When and How to Wax Your Fiberglass RV
Waxing after a wash protects the gel coat from UV rays and makes future cleaning faster. Apply wax only after the RV is thoroughly washed, rinsed, and dried. Avoid waxing in direct sun or over hot panels — the wax hardens before you can buff it off.
Not every fiberglass RV needs wax after every wash. If the surface still beads water and feels smooth, a wax every three to four washes is sufficient. If water sheets flat or the finish feels chalky, it is time to compound and wax.
FAQs
FAQs
Can I use a pressure washer on a fiberglass RV?
Yes, but keep the pressure at or below 1,200 PSI and hold the tip at least 12 inches from the surface. Never spray directly at seals, vents, roof edges, or decal edges, because forced water can leak inside and lift graphics.
Is dish soap safe for washing a fiberglass RV?
No. Dish soap strips wax and can dry out or etch gel coat over time. Use a pH-neutral RV wash or a mild liquid detergent that does not contain ammonia, acids, or caustic (high-pH) ingredients.
How do I remove black streaks from a fiberglass RV?
Black streaks are usually caused by roof runoff. A fiberglass-specific stain remover applied after washing handles them without damaging the gel coat. Avoid abrasive scouring pads or heavy solvents, which can haze the finish around decals.
References & Sources
- Crane Composites (Forest River). “Fiberglass Care & Maintenance Guide.” Specifies monthly washing with mild detergent, on a clean soft cotton cloth, and avoiding ammonia or caustic cleaners.