Here's an image of our frame to give you a good idea as to what we're building...as you can see it is all-aluminum, all-tube...full cage frame for maximum strength. (read below image for more information and details).
This image shows the bubble foil insulation. The insulation is mounted to the side walls before they are installed, this give full coverage and in most areas isolates the wood from the aluminum tubing...we do this for full coverage, not to purposely keep the wood from touching the aluminum. We have been building aluminum trailers since 2010 without any issues resulting from condensation or mold. In an interior aluminum skinned trailer you will/can get condensation to form on the interior walls with big temperature differences, but it is not forming inside the walls. I have never heard of the issue that you're describing but would think it's a sales tactic to explain why their method of building is better. I think it would be difficult to argue that a full cage frame isn't the best way to go, especially if you plan on encountering rough terrain. I don't necessarily believe that the way typical RV's are built is a bad thing or wrong, they build them that way to keep costs down, speed up production and maximize profits. The majority (and I mean over 95% of the manufacturers) build their RV's in a much different way than inTech RV. Companies whose focus is quantity over quality try to build their RV's for the lowest price possible, as quickly as possible and then compete in a market flooded with "me too" products. Most of the time these are large companies producing enormous numbers of RV's every year. For inTech, we focus our efforts on a smaller niche market...one where the customer is actually willing to pay a little more to have a very high quality product. I've always believed it's easier to explain my price one time rather than make excuses for my poor quality repeatedly. Our goal is never to be the biggest...our focus is on trying to be the best.
In the above picture you can see how we isolate the 3/4" premium plywood from the frame and outside elements...we use a layer of corrugated plastic above the frame, but below the wood. This layer provides protection from water and road debris. We use untreated premium 3/4" plywood because it is able to absorb the glues that we use to adhere the interior flooring. If we used a treated wood or a product like Adventech which would have much better rot resistance, the glues would not hold the flooring down...it's already to saturated with the chemicals that protect the wood from rotting. You read right above...we use 3/4" plywood...even in our products that you simply crawl into and sleep. I don't know of any RV's out there (including big Class A Motorhomes) that use 3/4" plywood...they all use 5/8" plywood on a framing system that is closer to 24" on center rather than 16"...and with spans that large on a thinner plywood the floor will feel very spongy. Go down to your local RV dealer and see for yourself, you'll be amazed at just how mushy the floors are when you walk across them. There's a right way to do things...and then there's the wrong way to do things...unfortunately, far too often our industry chooses the less expensive wrong way to do things. I don't mean to be picking on the industry in general, but the competition in each segment where RV manufacturers are battling for customers has gotten very tight...and that competition is driving quality and price down. On the surface the consumer loves the idea of getting into a 24' camper for under $15,000...that is until they own for a year, then they start to realize that their $15,000 didn't really get them what they thought they were buying.
I've always loved this saying..."There is hardly anything in this world that some man cannot make a little worse and sell a little cheaper...and the people who consider price only are his legitimate prey." I know your question wasn't really revolving around price or quality, but it's hard to delve into how and why we build what we build without touching on it. We like to think that what we're building is a lifetime product that you can either hand down or when you choose to sell it, it's actually worth something. I hope this explained a little bit of what you were asking, but please let me know if you have any other questions, I appreciate the interest!!
Can you expand on the metal frame a little more? When talking teardrops with some companies in trying to decide on a trailer several of them said they do not recommend a metal frame with wood or insulation tied to it as when temperatures go from cold to warm or warm to cold that condensation forms on the metal parts including the frame. When the condensation melts off it seeps into the wood and insulation and can cause mold after some time. They said this is why teardrops and other similar sized units don't use metal frames. No idea of this is a bunch of BS or not. Can you shed some light on this Rich?