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Why R-Values Mean Practically Nothing for RV Insulation

RV manufacturers talk up R-value insulation ratings like a magical barrier from the Old Man Winter. Unfortunately, despite what they often lead you to believe, R-values are less effective than you’d think. Spend any time camping below freezing in even “4 season” rated RV’s and you will quickly learn for yourself that these units just don’t cut it. The same goes for high temps. But why is that?

Today, we’re looking at R-values and why you shouldn’t put too much stock in them. Let’s get to it!

Why R-Value Is Meaningless for Your RV

R-value is an industry-standard measure of how well a material can resist heat flow. The higher the R-value, the better the insulation’s effectiveness in preventing heat transfer. These numbers are typically used to describe insulation so you know how good it is. However, a huge catch is how the material is used and installed.

To calculate the R-value of an entire wall, it’s essential to look at how the insulation is installed and all the materials used to build it. Even if you have R20 insulation in the wall, framing materials will significantly reduce the effective insulation number if they contact the outside material. These materials significantly reduce the insulation value.

RV frame melting snow
Our fifth wheel is one of the “best” rated for insulation. However, in cold weather, the frame will melt snow just like every other RV.

Frame and Chassis Components Conduct Heat

Visit any campground on a cool, moist morning or a snowy day and see RV frames. You will easily see the metal skeleton of the RV’s outlined where they conduct heat to the outside that will evaporate moisture and melt snow and ice. This is because metal is the opposite of an insulator, its actually a conductor. Aluminum, which is the most common material used to build RV frames, particularly conducts heat well.

Manufacturers often install insulation in the gaps in the aluminum frame between the fiberglass exterior and interior walls. However, heat and cold can easily pass through the frame and walls and is the far larger means of heat transfer than in the voids.

The only way to prevent this is to use an R-value material over the top of the metal frame, which takes up valuable space that RV’s don’t have. So you end up with almost no insulation in the frame areas. There are very few RV’s that add any intentional layer of insulation between the frame and walls.

Actual insulation in RV wall
This is a set of typical RV walls at a factory. While there may be insulation in some sections of the walls, this is all the insulation you get where the frame is located.

Lack of Thermal Barriers

Numerous areas throughout most campers lack important thermal barriers. Depending on the season, these allow the cold or heat to transfer in and out of the structure. During extreme weather, they can make staying comfortable inside your camper very challenging.

We’ve also seen some areas in campers without any insulation or thermal barriers. Our friends had a four-season bunkhouse fifth wheel with an outside kitchen under one of the bunks. When you opened the kitchen and bedroom drawers, you could see through to the outside. Nothing was stopping the hot or cold air from coming in. 

Numerous Holes in Roof and Walls

While the walls and ceilings may have some insulation, they also have numerous holes. Vents, doors, and windows are weak points in the structure that allow hot and cold air to come and go.

These may not be a big deal during normal weather but can be a problem during extreme weather conditions. Your furnace and air conditioners will work harder and more often to keep the temperature in check.

rv vent
Roof vents are weak points in an RV when it comes to insulation.

Windows

Your RV salesperson will likely boast about how amazing the view will be outside the massive windows on your camper. However, they likely won’t mention that these windows often result in an enormous loss of heat in the winter. The cold air from the outside will easily pass through them and into your camper. Additionally, the opposite will be true during the summer.

The more windows you have, the harder it can be to control the climate in your RV. Luckily, there are some things you can do to insulate your rig and stay cozy.

Can You Effectively Insulate Your RV

Sadly there is no easy option for making an RV as comfortable as a home in hot or cold weather. The only true way is to cover all the inside walls of the RV in a continuous sheet of insulating material. While this is possible its not usually practical, however there are some things that can drastically help.

Identify Areas Needing Insulation

One of the first things you should do to insulate your RV is to identify the areas needing help. You’ll likely feel the warm or cold air penetrating your rig. However, a temperature gun can help you quickly identify the most significant problems.

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If you want to take things to the next level, you can purchase a thermographic camera. These devices can help you to see precisely where hot and cold air enters the RV. You can also check the results once you’ve made any necessary adjustments.

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Some of the most significant issues are behind drawers and inside cabinets. If you have an outside kitchen, it’s a good idea to beef up the insulation in these compartments, too. Many manufacturers overlook installing thermal barriers here.

Seal Gaps and Cracks

Our friends found that their outdoor kitchen had zero insulation. Hot and cold air from this area easily passed through the drawers and into the bunkhouse. This made it nearly impossible for their children to stay comfortable during hot and cold weather.

Look for any gaps or cracks that let in cold air. The thermographic camera can help identify smaller spaces where air enters your room. Use fiberglass or panels of insulation to seal off these areas.

rv skirting for winter camping
Skirting your RV and eliminating gaps or cracks that will let cold air in is beneficial for winter camping.

Insulate Windows, Roof Vents, and Skylights

Windows, roof vents and skylights can be the biggest culprits for letting in hot and cold air. Luckily, you can insulate them to reduce any negative impacts. You can notice a significant improvement, especially in extreme conditions.

For windows and skylights, insulated curtains or Reflectix can have a tremendous influence during the summer and winter. We love Reflectix because it’s easy to customize based on your rig. In addition, it’s lightweight and easy to store when you’re not using it.

Finally, it’s essential to pay attention to roof vents. You can find vent insulator pillows that fit these spaces to help you control the climate inside your rig. They do a fantastic job of keeping hot and cold air out.

Sale
Reflectix BP48010 Double Pack Insulation, 48 in. x...
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insulation in our motorhomes windshield
Our motorhome’s windshield is a HUGE heat loss. On cold days, we place some reflective insulation over the glass, and it helps a ton.

Invest in Skirting

Skirting can be extremely useful if you’re setting up in a spot for an extended period. These materials surround the bottom of your camper to keep the cold air from blowing under your unit. This protects your sensitive plumbing and other components and helps keep your floors warmer.

Unfortunately, skirting can be expensive and physically demanding to install. In addition, some RV parks and resorts have strict rules against their use. Before investing in skirting, it’s a good idea to ensure you’ll be able to use it. If not, you could end up wasting your time and money.

Pro Tip: If you’re looking for a truck camper, learn which ones are best for four-season camping.

The Best RV Winter Setup: How to RV in Winter and the Gear That Will Keep You Cozy Warm!

RV R-Value Isn’t All It’s Cracked Up to Be

So it mainly comes down to how an RV is built. The metal frame and limited space make effective insulation very difficult. Most manufacturers compensate for this with excessively large heating and AC systems. Cars are no different. The AC system in your vehicle might be almost as powerful as your home!!

Overall, every RV is a challenge when it comes to insulation, but with these tips, cold or hot weather RVing is possible. Just expect to spend more on heating and cooling costs per square foot than a home.

Have you experienced some of the issues we listed? Share your stories in the comments! 

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About Tom Morton

Tom, a Pacific Northwest native, is our technical genius. Born in Washington and raised in Alaska before settling in Michigan. He's the man who keeps our operation running, both figuratively and literally.

With a background in Electrical Engineering, Tom specializes in RV solar systems and lithium batteries. He made history as the first documented individual to use a Tesla battery module as an RV battery. Tom has personally assisted countless RVers with system installations and has educated thousands more through his videos and articles.

Cinematography is another of Tom's passions, showcased in his work on the Go North series. You can see his camera skills on display in The RVers TV show on Discovery Channel and PBS where he also stars as a co-host.

Tom's mechanical expertise extends beyond RVs to boats, planes, and all things mechanical. He's renowned for taking on maintenance and repair projects single-handedly and is often spotted underneath RVs, making him the technical backbone of our endeavors.

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Steve C

Wednesday 27th of December 2023

The BEST remedy I've found to escape harsh weather is to put your RV into storage and head to a tropical country. I do this every year as I hate the cold. Problem solved and it's cheaper and safer outside of the US.

The Mortons

Sunday 7th of January 2024

That does sound like the perfect way to escape the cold Steve! Hope you're enjoying whatever tropical country you're in this winter!

Steve

Wednesday 27th of December 2023

This is very interesting article as I presently have an Alto trailer from Safari Condo that has very poor insulation with lots of windows. We have been using the trailer in winter as it is parked for the season at a recreational park that has great facilities for washing and even cooking. Last year I add foil insulation to all the walls using two sided removable tape. I also added playroom padding to the floor. This greatly improved the interior comfort and we even felt ok at -30 celcius. We are now looking to sell the trailer partly due to the poor insulation but also becasue we want something a bit roomier. So it's very interesting to learn about your analysis of R factors and the hype around it by the manufacturers. This is making me think twice about which trailer to purchase and it's also disappointing to learn how we are deceived by the marketing hype. Thanks for your highly informative and practical articles.

Ray Davis

Wednesday 27th of December 2023

Nice to see an article on this subject. After over 4 decades in the energy efficient home building sector, the R values touted are likely true when applied to the insulation itself, but not when incorporated into a wall system. System refers to all components such as framing and glazing. Terms such as, double layer, mean nothing overall, but sound nice. My guess for a reasonably insulated TT as an ovarall structure, maybe an R-3. Even small gaps significantly reduce the wall or roof system as a whole. One summer or winter season will educate everyone in a hurry. But thats OK, because we are all adventurers, right?

Tom Saunders

Wednesday 27th of December 2023

Great blog on cold camping. Very well presented and articulated. You reminded me of having switched to lithium batteries,I can now enclose and insulate my battery compartment! You guys rock!