RV Tech Q&A: Aluminum Siding Versus Fiberglass

Q. We’ve been looking for a new trailer and have a question regarding the relative merits of aluminum siding versus fiberglass. It appears, from the salesmen we’ve talked to, that aluminum has the advantages of overall trailer weight, the ability to repair easily and cost. Gelcoat fiberglass presents a seamless appearance and claims of increased durability as compared with aluminum. We don’t want to have to purchase a new larger truck at the moment, so weight of the trailer is a factor, as is cost. Can you discuss the pros and cons of each material to help with our decision, please?
R/J. M., Saratoga, California

A. First of all, you should remember that any salesman you’re talking to is going to promote the positive aspects of his company’s product, no matter what it is, at the expense of the competition’s product. That said, both side wall materials are popular and durable and can offer long-term cost-effective benefits for the RV buyer.

Corrugated-style aluminum is often used on lower-cost RVs because it’s inexpensive, and
repairing it is normally a simple process of replacing panels rather than repairing the
existing panels. Smooth aluminum of the type used on higher-priced RVs can be costlier to
repair because the shop is dealing with larger pieces of material. Smooth fiberglass can
often be repaired in the same fashion as an auto-body panel, using filler and a fiberglass
patch kit, so replacement of large body sections isn’t always necessary. The costs
associated vary greatly depending on the size and location of the damage.

As for durability, each material has its good points and will deliver good service. A
bicycle handle that accidentally bangs lightly against the side of an RV may bounce off
fiberglass, leaving it unscathed, whereas corrugated aluminum may be somewhat dented. A puncture in a fiberglass side wall or molded end cap, after a heavier impact, may call for
a major hole repair, while the aluminum panel, similarly damaged, may need to be completely replaced at a widely-varying cost. There’re good points to each siding material.

The weight question is a toss up. Fiberglass that’s manufactured with a lauan plywood
backer can be pretty heavy, and doesn’t necessarily provide much, if any, weight advantage. Better to look at size and options when you’re looking at the lower-weight aspect of your prospective trailer. — Jeff Johnston


  1. Over the years I have owned many travel trailers. I have noticed many alluminum older trailers are still on the road. The fiberglass trailers with age on them delaminate thus the value becomes zero.

  2. We are the company handling with RV trailer, Carava accessories such as GRP boart, Corrugated-style of Aluminum boart, Stabilizer Jack,Caravan door, lithium battory, 12V refrigerator and air conditioner for caravan in China. According to our experience as supplier of the caravans and RV trailer factory, we suggest you use GRP boart as wall, Corrugated-style of Aluminum boart as floor, it will be light and strong with the caravan. If you need more information, pls contact us as [email protected].

  3. Our first fifth-wheel was used and had aluminum siding. We had to replace some siding and repair the wood frame. We found it was more prone to leaks due to all the joints and the siding was simply fastened with a staple gun, which also created a corrosion between steel and aluminum. Fiberglass only from now on.


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