Some used RVs I’m looking at have a ‘303 roof.’ What is that?

Dear Dave,
I am currently shopping for a Class A Phaeton 36 GH, and I see a lot for sale with comments about a 303 roof. The factory brochure for the Phaeton states that it has a fiberglass roof. I looked up 303 and it appears to be a UV treatment for rubber roofs. Is there an advantage to 303 on a fiberglass roof, or would it cause damage? Thanks. —Mark, Tiffin Phaeton 36 GH 

Dear Mark,
There are several materials used for the outer skin of the roof in RVs including EPDM, TPO, PVC, Alpha, and many more. However, there is no 303 roof material. It never ceases to amaze me what people try to pass off in sales “lingo” or as a hook.

I often get accused of not answering the question right away, but rather taking readers on a “Route 66” journey. So, yes, there is a slight advantage to using 303 on fiberglass and, no, it will not cause damage.

History of 303 Protectant

303 Aerospace Protectant was introduced in 1980 and developed by Dennis Praegitzer for the aerospace industry as a protective treatment for rubber, vinyl, and plastic. According to the website, Dennis worked for more than two years with a top polymer chemist trying 50 different formulas until they came across the first product that actually screened against UV and ozone degradation.

I believe it started out as 303 Protectant originally, and was renamed 303 Aerospace Protectant a little while later. When I worked at Winnebago Industries, we recommended the 303 product to protect not only the fiberglass outer skin, but the dash material, bumpers, and anything that was exposed to the sun. We even got the company to furnish us with 3 oz. spray bottles that went into every owner’s packet.

Fiberglass material on sidewall

We used a beige fiberglass sidewall skin that would turn almost pink due to harsh exposure to the sun. There were thin clear coat outer layers, called “gel coat,” as the gloss would highlight every bump, dimple, and wave in the sidewall. If you look at the older units, you will see a dull finish with the fiberglass strands visible. This fiberglass material would start to fade very quickly as there was no UV protection in the resin that binds the fibers. With little gel coat, nothing was added to that, as well.

Back then, 303 would help somewhat, but not much. There was nothing else on the market that would help, other than to repaint it. 303 was good for treating the dash that would get exposed to the sun, plastic bumpers, wheel well linings, and rubber seals. I remember seeing units that had originally started as beige in color and after only one year, the plastic around the wheels was almost white, the sidewall was pink, and the dash was hazelnut. That is not my term—rather, my wife told me that!

Don’t let 303 freeze

One tip: Do not let 303 freeze. I had some extra product that I kept in the garage over the winter. The next spring I applied it to the dash of my car and the entire dash cracked like dirt in the desert! I couldn’t figure out what happened, since 303 is 75% water and figured that it should thaw without an issue. But my contact at 303 stated that the “proprietary chemicals” break down when frozen. He wouldn’t tell me what those were.

Today, most RV manufacturers use a Filon product that has a very high gloss finish and does have some UV protection built in on the sidewall. If you look at the roof fiberglass, it has less “shine” to it due to cost—and the fact that it is out of sight, out of mind. Crane Composites recommends using Meguiar’s 59 Boat and RV Wax; however, they do not specify sidewall or roof. This wax has additional UV protection.

I prefer using 303 Protectant as it is much easier to apply with a mop. The advantage is it will provide UV protection, which will not only keep it from fading, but also from developing spider cracks. These can eventually allow moisture penetration and problems down the road. And the 303 will not ruin your fiberglass.

 You might also enjoy this from Dave 

Is UV protection required on all RV roof materials?

Dear Dave,
Are you aware if Crossflex membrane requires application of UV protectant solution? There is no info in Dicor’s specs about that. In fact, the specs only contain cleaning info! I’ve found on the web that Camco recommends against using UV protectant for TPO membrane but I’ve found nothing about Crossflex. Many thanks. —Mark, 2023 Coachmen Cross Trail 23XG

Read Dave’s answer.

Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”

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