Friday, June 2, 2023


What’s the best RV roof material?

Dear Dave,
My wife and I want to trade up to a small (25 feet or under) Class C motorhome. We looked at two, one made by Thor and the other by Coachmen, that had Crossflex roofs. Can you tell me what a Crossflex roof is made of and whether it is equal to or better than a TPO or EPDM rubber roof, or just a product that is less expensive? What maintenance is required with that type of roof? The salespeople were no help at all and didn’t seem to know much about them. We initially looked at a Winnebago Class C with a fiberglass roof, but that seems to reduce the cargo-carrying capacity substantially, due to the weight of the roof. Thank you. —Steve, Flagstaff Microlite 21FBRS

Dear Steve,
The roof material market has exploded since the late 1980s, when the first rubber roofs started showing up on RVs.

RV roof materials: The invention of EPDM and TPO

I was working at Winnebago at the time, and most manufacturers were using a two-piece aluminum roof material. This was very expensive, so someone decided to use ethylene propylene diene terpolymer (EPDM) instead. At the time, EPDM was being used on industrial buildings and flat-roof houses. The rubber membrane was cheap and very easy to apply just by rolling on adhesive and stretching the membrane over the roof, then adding trim to the edges.

Over the years, the EPDM started to lose its popularity due to the chalking and bubbling. It even had problems where it would detach from the roof. So thermoplastic olefin (TPO) came on the market, which was marketed as a superior material from EPDM and needed less maintenance and conditioning. Over the past few years, there has been an explosion of new materials marketed as “Plastic” and “PVC” and other fancy names such as Diflex, and Tuff-Flex, Alpha Systems Xtreme, and others, all designed to get away from the bad vibes of a rubber membrane.

RV roof materials: Dicor Crossflex

I did some research on the Dicor Crossflex and it seems to be a good product with nylon fibers cross-webbed throughout the material. In one of the info sheets I came across, it is described as the first synthetic thermoplastic material on the market, which makes me believe it is a TPO material with nylon reinforcement. They claim it is three times stronger, puncture- and tear-resistant, and has superior UV resistance, as well. So I don’t believe it is a cheaper product than the others on the market. According to the marketing material, it only requires occasional cleaning with Dicor cleaner, 409, or mild detergent.

An rv roof to look at the best RV roofing materials

What’s the best RV roof material?

In my opinion, fiberglass is the best RV roof material on the market as it adds to the structural integrity, is UV resistant, and needs very little maintenance. It also does not expand and contract with temperature changes and road abuse, so there is less sealing required over time at the roof to the sidewall, backwall, and front cap seams. It also does not pull away from opening cuts in the roof like skylights, vents, and air conditioners.


I believe someone that did not have a fiberglass roof told you it added weight and that is why the Winnebago has less cargo-carrying capacity. I have a 4” square of fiberglass material that weighs no more than a 4” square of EPDM and Alpha Systems. Therefore, a 25’ unit would not have substantially more weight with fiberglass.

I know that Winnebago uses superior fabrics, heavier-weight carpets, and superior cabinetry that will add weight to the dry weight of the unit and reduce cargo-carrying capacity (CCC). Plus, you need to make sure you are comparing like units that are on the same chassis. The Mercedes cutaway chassis will have less CCC than the Ford E-450, which can both be available on a 25’ unit.

More on weights of roofing materials

If you Google search “fiberglass vs. rubber membrane” you will find several websites that claim rubber is lighter, while just as many state the opposite, all without any actual testing or facts. According to Amazon, a 25’ x 8’ roll of Dicor DiFlex II weighs 48 lbs. I assume the Crossflex would be similar. I contacted Crane Composites and they sent the Technical Data Sheet that lists the .04″ thickness, which Winnebago uses, at 0.28 lbs/ft2. The same 8′ x 25′ measurement is 200 SF, which is 56. Keep in mind if the unit is 25′ there most likely wouldn’t be 25′ of material as the roof would stop short of the cutaway cab, so the difference would be even less. Sounds like a sales line?

Even though I feel fiberglass is the superior roof material, I would not say that TPO brand materials can’t be used. They just require more inspection and maintenance, and the true test is what the material looks like 10 years later compared to what the fiberglass material looks like. It is a cost factor, but we all know how looks affect resale value.

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Dave Solberg
Dave Solberg
Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club. He has been in the RV Industry since 1983 and conducts over 15 seminars at RV shows throughout the country.


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Bob Mac
23 days ago

Way back in 2001 I bought a new Winnebago Chieftain with a fiberglass roof. I asked the service manager about the reliability and he said he didn’t know much about them because they had never had a customer come back with a problem. Sold it after 9 years and zero roof maintenance and it still looked good as new.

23 days ago

I’d pick aluminum 1st, like my Itasca Sunflyer 22′ class A and my 2002 Lance 1120. Fiberglass a close 2nd as on My BT Cruiser. My dog lives under the same roof as I, so I don’t need a doghouse.

23 days ago

PVC is an awful product for roofing. EPDM same thing, bad products. In the single ply r product lines, TPO is currently the best on the market.

Nothing in the RV industry comes even close to fiberglass though. Without question, if you are on the fence about fiberglass roofing, get off the fence and never ever have an issue with the roof again if you choose a fiberglass roof. TPO is a distant 2nd but is the best of the plastic, rubber roll roof lines.

23 days ago

Dave, I couldn’t agree more that fiberglass is the premium RV roofing material.

Having owned numerous RVs over more than 40 years, I’ve had aluminum, various “rubber” roofs, and fiberglass. Earlier this year I inspected an Alliance 5er with a PVC fabric type material (almost like canvas) that I wouldn’t put on the roof of a dog house!

I am meticulous on keeping an RV roof clean and maintained. By far, fiberglass is my roofing material of choice. Definitely the easiest to maintain and it lasts. Whatever it costs, it is worth it!

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