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What You Need to Know About RV Frames

The frame of an RV is the interior structure of your home on wheels. In other words, it’s your RV’s skeleton. It’s one of the first pieces of your RV the manufacturer put together to provide the groundwork for your walls, windows, and doors. Frame design and construction vary but greatly impact how the RV performs and how well it will withstand road abuse. We personally have had 4 RVs and driven and rented many more testing out many of the frame types. Today were going to share what you need to know about them.

Chassis Vs Frame

Before we dive too far into frames, let’s clarify one thing. The frame we are going to talk about is mainly the part that makes up the “house” of the RV. The chassis is the part that includes axles, wheels, drivelines, and an engine if it’s a motorhome. Almost all RV’s are built on a chassis that they purchase from another manufacturer. While the chassis strength and design have a huge impact on the performance of the RV, when we say frame, we will be talking about walls and roof.

Class A motorhome chassis
This Class A motorhome chassis is what the RV frame will be built on.

What Is the Frame of an RV Made Of?

RV frames are usually steel for the chassis and aluminum or wood for the house structure. However, some manufacturers use steel, and even others use fiberglass for the structure of the RV. Each type has its advantages and disadvantages.

Many refer to RVs with wooden frames as “sticks and tin” campers. They consist of a wooden frame, plywood walls, and an aluminum outer wall. They’re usually affordable and easier to repair, but they also tend to be more flexible and more vulnerable to water damage

In contrast, RVs with metal frames typically have aluminum and/or steel tubing for their structure (although aluminum is more common). The walls consist of laminated fiberglass, styrofoam board insulation, and thin plywood—all laminated together. This type of RV is generally a little more expensive and but can suffer from delamination if water seeps in, but they are also very durable, lightweight, and less likely to dent. 

Like mentioned above the RV frame is different from the chassis. The chassis is the platform your RV is on, and in motorhomes, it typically includes the engine and transmission. The chassis is usually carbon steel or aluminum alloy and isn’t usually a part of the actual RV’s house frame. 

Many times the frame is actually multiple different materials. For example the chassis is steel, walls are aluminum and roof is wood in the photo below.

wooden roof on an RV at factory
This RV has a steel frame, aluminum walls and wooden roof

Pro Tip ➡ No RVer wants to find delamination on their camper, but unfortunately, it happens. If you suspect a water leak, learn How to Stop and Fix Delamination on Your RV before it gets worse.

Custom Frames vs. RV Supplier Frames

Even if two RVs use the same materials for their frame, it doesn’t mean they’re the same. Some camper manufacturers make custom frames designed specifically for the RV’s intended use. For example, a manufacturer that makes heavy-duty, off-grid travel trailers may choose to make their own frames to ensure they’re up to the task. 

Most trailer and motorhome manufacturers produce their own frames so they can customize layouts but some use frames from other suppliers. These frames are usually mass-produced and are a “one-size-fits-all” approach. With these you’ll receive the benefits of tried and true building methods. These are usually van conversion builds and high-end motorhome bus conversions.

van camper retrofit at midwest automotive
Van based RV’s usually just use the frame from the manufacture

How Are Camper Frames Held Together?

What keeps these frames from falling apart? That depends on the type of frame you have. Wooden frames are usually held together with screws, staples, or both, while metal frames are welded, huck bolted, riveted or screwed and glued together.

At first glance, you may think that one type of frame is obviously better than another, but this depends entirely on the quality of the building process. Wood frames can be better than metal in lots of ways.

Benifits and Drawbacks of Different Frame Types

Lets take a look at the different types of frames and a few of their major benefits or problems.

Wood

In a camper frame, wood is far less thermally conductive and tends to help insulate a camper better than steel or aluminum frames. Its a cheap building material and can be very strong when properly constructed. Wood frames can also flex more than metal without breaking, which can actually be a good thing. A properly built frame with some flex can “bend” instead of breaking. Cracked welds can be catastrophic.

Wood however has its limits and is not as strong as other frame types. In an accident wooden trailers tend to disintegrate. Wood is also susceptible to rot and insect or rodent damage. Water damage can not only rot the wood but rust screws and cause it to come apart. Wooden frames can be good but its critical to keep water out.

wood frame

Aluminum

Aluminum is very strong for its weight capabilities and tends to hold up well to a leak with minimal to no structural damage. It can allow for large specialized shape RV’s while keeping weight down significantly.

Aluminum is very heat conductive and can transmit alot of heat into or out of an RV. Its easy to see the aluminum frame on a cool dewy morning because of the heat loss through the walls. Aluminum is also strong until it bends as it tends to crack. Cracking welds on aluminum frames are common. Some manufacturers get around this by using rivets or screwing and gluing aluminum together. (ever noticed this is how airplanes are built) This allows for some movement without breaking.

Tom looking at aluminum frames

Steel

Steel is the strongest frame type available. Its almost always huck bolted or welded together and can support lots of weight. Big heavy motorhomes frequently have steel frames.

Steel like aluminum is a good conductor of heat (slightly less than aluminum) and will lessen the insulation of an RV. Steel also holds up well to water but is subject to corrosion (rust) if left wet. Steel is more bending tolerant and less likely to crack than aluminum. Steel almost always ends up being the heaviest frame type, but also the strongest.

Steel RV Frame
This is the frame of our motorhome, its completely steel and while strong its very heavy.

Fiberglass

Fiberglass is a less common building material and is usally used on smaller trailers, fifth wheels and truck campers. It can be a fantastic option in between wood and metal. It’s lighter than steel but stronger than wood and is not as thermally conductive, making them better in hot and cold weather. Fiberglass also stands up well to water and is not as likely to be damaged.

Fiberglass needs to be formed into special shapes to produce its strength and can be challenging to work with. This tends to make fiberglass RV’s very expensive. Because of its challenges, there are also more design constraints and you are less likely to see as many layout options or slides.

fiberglass rv frame
This RV has a fiberglass Frame

Potential Problems to Look Out For

It can be hard to know if your RV’s frame has potential problems. After all, it’s behind the walls. Nevertheless, if you’re able to set eyes on a portion of the frame (maybe during some repair work), take a look at the quality of the materials. Do you see any cracks in the wood? Does it seem like only a few staples are holding it up? Do the boards seem warped or hastily put together? These are all signs of a poor-quality wooden frame.

RV wood frame
If you have a wood frame, look for cracks and damage or screws and staples that might be separating from the wood.

As for metal frames, you’ll want to take a look at the weld quality. Is there any cracking, incomplete fusion, or excessive globules of metal? These are also signs of poor construction, and you’ll most likely see other signs of low-quality materials elsewhere in your camper.

How Do You Know What Frame Your Camper Has?

Sometimes its hard to tell what type of frame an RV has, but there is a general rule of thumb. Simply look at the outside. Does it have smooth sides made of fiberglass? If so, your RV likely has an aluminum frame. Does it have wavey sides made of aluminum? If so, your RV probably has a wooden frame. This does not always hold true, however. Kingstar and Rugged Mountain have smooth sides but use wooden frames for their flexibility and delamination advantages.

Moreover, if you have an Airstream or molded fiberglass RV (such as a Casita), your RV is in a league of its own. These manufacturers broke the mold to produce higher-quality RVs, and for their specific building processes, we recommend visiting their websites. 

Casita travel trailer
Molded fiberglass RVs are some of the longest lasting campers on the market.

How to Know if an RV Frame Is ‘Good?’

Many factors influence whether or not your RV frame is of good quality. And while most RVers have their preferences when it comes to wood or metal frames, it really depends on the manufacturer.

For example, many people automatically believe that aluminum frames are better. But, if the manufacturer heedlessly assembled your RV with little care and poor welding, a carefully constructed wooden frame will likely outlast it any day. 

Ultimately, you’ll want to ensure that you’re purchasing your RV from a reputable manufacturer with a satisfied customer base. Unfortunately, the price of the RV will usually determine the quality. Was your RV mass-produced and priced to sell quickly? If so, this could be a potential red flag. 

➡ While price often determines quality, you can still find amazing RVs at reasonable prices if you know how to search and negotiate. Check out our top buying tips: How to Buy an Awesome RV Without Breaking the Bank.

Make Sure Your RV’s Frame Is Up to the Task

All RV frames aren’t the same. Depending on the type of RV, they can be wood or metal, and they can either be custom-made or supplier-made. These factors all influence your RV’s quality, price, and resale value.

Regardless of what you choose, it’s important to understand the construction of an RV and the care the manufacturer took to make a good quality rig that’s ready for all of your future adventures. 

RV assembly

Besides the overall construction, make sure you’re aware of the Top 10 Easily Missed Things to Look for When Buying an RV.

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About Tom and Caitlin Morton

Tom & Caitlin Morton of Mortons on the Move gave up the stationary life for one where they are constantly on the move. They are full-time travelers, television hosts, and digital media producers.
They left their jobs, sold their house and possessions, and hit the road in September 2015 in their full-time “home on wheels”. Since then they have traveled the US, Canada, and even internationally by RV.
Now, they are Discovery Channel & PBS TV Co-stars of “Go North” on Amazon Prime Video, co-founders and instructors of RV Masterclass, and contributing authors for Hwy.co and an Arizona travel guide.

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Jerry

Tuesday 27th of February 2024

What's your take on how Azdel stacks up to other frame materials?

Tom and Caitlin Morton

Thursday 14th of March 2024

I like composite materials in general as RVs's will eventually leak and they might stand up better. I think some of the claims are exaggerated about thermal and sound transmission. For the sake of lack of moisture damage however I think its a great choice for longevity.

Marcita Scharnhorst

Wednesday 14th of June 2023

Yes indeed frames are not built now how they were in times past. We have a 2017 Jayco fifth wheel camper with a collapsed frame. Both Jayco & Lippert frames refuses to accept responsibility.