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What is an Underbelly on an RV? (Motorhome FAQs)

What is an Underbelly on an RV? (Motorhome FAQs)

When you’re new to the world of recreational vehicles, dealing with all of the varied terminologies can be intimidating. After all, when flipping through your RV handbook, it’s important to know the official terms of the parts of your RV that you’re reading about.

For example, when it comes to the underpart of your RV, this area is most commonly referred to as the underbelly.

So, what exactly is an underbelly on an RV?

The underbelly on an RV is the enclosed space on the underside of the RV that provides protection for pipes and tanks. In winter, this area can be insulated and heated to protect water lines from freezing or bursting.

Overall, it is important to always make sure the underbelly of your RV is in tip-top shape since this barrier protects both the base and foundation upon which the rest of your RV design is built.

Continue reading to learn more about RV underbellies, including what the underbelly of an RV is, as well as the most common materials that RV underbellies are made of, and more.

Definition of Underbelly On An RV

The underbelly of an RV refers to the entire underpart of your RV. If you want to pinpoint what this is on your recreational vehicle, lay down on your back and slide your body under your RV. When you look directly up, you will see the underbelly. 

The underbelly of your RV is usually made with a protective sheet of coroplast or aluminum that covers the entire base of your RV.

Take note, that it is essential that you maintain the upkeep of this part of your RV as this protective barrier works as the main defense between the foundation of your RV and all the extreme terrain your RV experiences.

What Material is Used on the Underbelly of An RV?

Sheets of Coroplast

Sheets of Coroplast seem to be the most common material used by most RV makers when it comes to the construction of an RV underbelly. This material is not only able to be attached to the underbelly of most RVs quickly, but is also known to be a cheap, yet reliable material.

Chloroplast sheets are also a great material to use when performing at-home repairs to the underside of your RV since they can be secured in place by self-tapping screws as well.

These sheets are also designed to be handy when you need additional insulation below your RV, despite looking more like a cardboard box than any tougher material.


The newest underbelly material available on the market today is called AccessiBelly RV Underbelly. This material enables technicians to simply drop one panel and avoid cutting holes in the material during installation.

AccessiBelly, like Coroplast, is composed of corrugated plastic, but its design allows you simpler access to your components, hence the name. However, there is a significant disadvantage to this strategy.

While its design allows for simple access for a technician to perform repairs, it appears that it can also break without warning.

So, if your RV’s underbelly is made of this newer material, it is suggested that you only allow technicians with expertise dealing with AccessiBelly to do any work or repairs on your RV to avoid future complications.


Aluminum can also be used to construct the underbelly of an RV. For example, this material is most commonly known as the material that is used to make the underbelly on all Airstream trailers.

Aluminum is another common RV underbelly material.

Aluminum is also said to be more corrosion and dent resistant than other materials used for RV underbellies.

Can You Repair the Underbelly of An RV?

If you find that your RV is leaking from underneath, your vehicle may be suffering from underbelly damage.

While there are a variety of causes for this, including pipes becoming broken or just falling off due to corrosion, you must fix the underbelly of your RV as soon as possible. 

Unfortunately, if this problem is not fixed, the vehicle will continue to leak fluids while you are driving and potentially cause harm to other parts of your RV.

Fortunately, depending on the material used to make the underbelly of your RV, you should be able to perform any needed repairs at home. Take note, however, that all repairs will need to be done carefully and you should also have some help when you are doing this repair. 

For example, the material of the underbelly is often heavy and comes attached to your RV as a one-long piece. You should, therefore, have a friend help you to make sure the material doesn’t come crashing down on you during your repairs.

How to Repair the Underbelly of An RV

Depending on the material used to construct the underbelly of your RV, will determine how you go about performing repairs.

For example, given the seriousness of the problem, you may be able to get away with using tape designated for this area if the underbelly is made of a flexible tarp-like material.

Alternately, if you have sheets of Coroplast or other such materials, you may simply remove the damaged sheet and replace it with a new one. These sheets are often fastened with screws or nails, and to remove the old one, you just take out the screws or nails.

Take note that RV manufacturers may also cover the underbelly of your RV with a single, solid piece of corrugated plastic. If this applies to your RV, you may need to rebuild the underbelly and install smaller sheets there. 

Overall, considering there is a multitude of ways to repair the underbelly of your RV, it is always recommended to read your RV’s model’s manual before starting any home DIY repairs yourself to make sure you will be able to both start and finish the project yourself.


Closing Thoughts

The entire underside of your RV is referred to as the “underbelly” of an RV. The underbelly of your RV is usually made with a protective sheet of coroplast or aluminum that covers the entire base of your RV. If you notice that your RV is leaking from beneath, you must repair the undercarriage as quickly as possible.

Unfortunately, a variety of circumstances can cause underbelly damage, but if this problem is not rectified, the vehicle may continue to spill fluids while driving, which can negatively affect other components of your RV.

In conclusion, it is always advised to study your RV’s model handbook before beginning any home DIY repairs to ensure you will be able to start and finish the project yourself.

This is because there are several ways to fix the underbelly of your RV and you’ll want to make sure you don’t cause any further complications.


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