Illustration for Pressure Washing an RV

It’s a common question. In an RV owners’ community last year, someone asked what to wash a rubber roof with. The replies split between dish soap, car wash soap and roof-specific cleaners. This summer, one owner of a new trailer with a TPO roof asked how to wash it and touch up the seals. The trailer had likely sat outside for two years before the sale. Another owner was washing to get ready for resealing. That owner found the old sealant cracked and peeling away in spots.

The checklist, surface by surface

No roof maker’s guide we read gives a safe psi for the roof itself. The only firm pressure numbers came from a graphics maker’s care sheet. One RV builder includes it in its owner documents.

Surface What the maker’s guide says Pressure washer?
EPDM rubber roof (Dicor) Wash 3 to 4 times a year; non-abrasive cleaner, medium plastic bristle brush, garden hose rinse No psi given; brush and hose
Roof membrane (Alpha Systems) Clean 3 to 4 times a year; dish soap, medium-bristled brush; no acetone or petroleum distillates No psi given; brush and rinse
Polypropylene skylights (Alpha Systems) No pressure washer; force can damage seals and push water under flashing No
Vinyl graphics (3M sheet in Brinkley RV’s owner documents) Under 2,000 psi, under 140°F, 40° fan tip, at least 1 ft away, square to the surface Yes, within limits
Fiberglass gel coat sides (Talon sheet hosted by Forest River) Mild detergent monthly, soft cloth; nothing abrasive, high-pH or ammonia-based No psi given; go gentle
Sealant at roof edges, vents, doors (Jayco manual) Inspect at least every six months; reseal at least once a year Not addressed; we’d keep the jet off it
Underbody (Jayco manual) In road-salt areas, spray with a high-pressure hose every wash Maker says a high-pressure hose

Brush the roof, don’t blast it

Both membrane makers describe the same routine. Use a mild cleaner and a medium-bristle brush, then rinse well, three or four times a year. Neither gives a pressure setting, so a garden hose is the safe rinse. One maker warns that acetone and anything with petroleum distillates will damage its membrane. Both care sheets come from suppliers with addresses in Elkhart, Indiana. If your roof paperwork names one of them, follow that maker’s sheet rather than a generic guide.

If mildew has set in, one maker’s guide says not to rush. Work in small 2-by-2-foot patches with a bathroom mildew cleaner. Let it sit 3 to 10 minutes, then scrub. Rinse the windows and sidewalls too. That cleaner shouldn’t touch painted or aluminum surfaces, so wipe any drips off the sides right away.

Decals have firm limits

The graphics care sheet says hand washing is better. If you do use a pressure washer, it sets limits:

  • below 2,000 psi and 140°F
  • a 40-degree tip
  • held at least a foot away and pointed straight at the panel

The key warning is about edges. Never aim the stream at a low angle (0 to 60 degrees) toward a decal’s edge. That can lift the film. Brush-style car washes can also dull graphics or lift edges.

Check your own machine’s rating against that limit. Our electric or gas pressure washer guide explains what to look for.

Sides, seals and skylights

Gel coat sides want gentle soap and a soft cloth, not stiff bristles. The skylight maker is blunt: no pressure washer at all. Its reason is that force can damage seals. That applies to other seams, vent caps and window gaskets too. Our advice is to spray across them from a distance, never into them. Our list of what to cover before pressure washing applies here too. That’s especially true for outdoor outlets and the shore-power inlet.

Washing is also your inspection

One trailer maker’s manual says you or your dealer must inspect all sealants at least every six months. Check the roof and all four sides, including moldings, doors and vents. Reseal at least once a year with the same type of sealant that was removed. The manual also says its warranty doesn’t cover water damage from failing to maintain or reseal.

Some motorhome warranties go further. One maker’s 2021 warranty guide requires annual inspections to keep its structural and lamination coverage. An authorized RV dealer or an RV repair service it approves must do them. The owner must keep proof, and the first one is due by the first purchase anniversary. In an RV owners’ thread last fall, an owner posted that checklist. They wondered what it would all cost and whether a dealer would even do it. This isn’t legal advice. Read your own warranty guide. Ask the maker who counts as an approved inspector.

Before it goes into storage

The same trailer manual has a storage list:

  • Wash the outside thoroughly.
  • Check the roof for damage or leaks that might otherwise go unnoticed.
  • Close the roof vents.
  • Cover the air conditioner.

It also warns that 8 inches or more of snow, or 2 inches of ice, puts excessive weight on the roof.

Then put your own machine away properly. Our winterizing routine for pressure washers shows how. If you also wash the house this fall, follow what to do before, during and after a pressure wash. Our methodology page explains how we check sources.

Sources

Based on 9 sources · How we price

Checked 2026-10-09. Makers’ guides are cited for what they say about their own products. No maker endorses or is endorsed by this site.