RV Construction Methods – Insulation

One thing missing in my research on fulltime RV planning is a one stop reference to compare RV construction methods.  So, I decided to start a page on the blog to park my notes in regarding anything construction related.

The first area I have researched to any degree of completeness are the methods used for insulation of what most would consider to be fulltime rigs.  Here is a link to all my notes if you are interested.

At this point Karen and I have decided a fifth wheel most meets our expectations in terms of our wants and needs when traveling and living in an RV.  Budget for the rig purchase will play a major role in what we end up purchasing.  Perhaps what we decide to be our favorite floor plan will dictate the size of the unit. In the end, we will narrow the selection down to a few different companies who build a rig matching what we want.  Which brings me to the main point related to RV construction methods.  Whatever RV manufacturer we end up buying from will have their own standard construction methods with maybe a few options. For the most part we will be stuck with those standards. I believe having a basic understanding of as many construction methods as possible will help us make an informed decision on which manufacturer to buy from.

At this years local RV show I noticed a few construction methods that others may have passed over unless they had done minimal research. I’ll spare you the details but will summarize this by writing some of the manufacturers may have been stripping down rigs to be more price competitive. A year ago I would not have known the difference.

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Summary of what I plan to do when selecting a rig after considering insulation methods.

I’ll be selecting a rig that has been tested for how long it will hold heat in a chamber during the test.  We will be getting a rig that has double-pane windows, has reasonably insulated slides and is setup to reduce noise coming from the mechanical systems (air conditioning) and from outside the rig.  We want a four seasons rig but don’t necessarily require the “best” insulation as we will avoid harsh climates. I know that we will be forced to except whatever insulation standards are available from whatever fifth wheel manufacturer we select to buy from.  That manufacturer will not necessarily have the best all around insulation methods.

I don’t want to repeat much of what you can find in my notes described within the insulation page under construction methods. However, as many rigs are using foam for insulation I felt okay to repeat what I believe to be a good comparison of types of foam. Perhaps this will spark a few comments from those more knowledgeable in the area than myself.

On a cost-per-R-value basis, rigid foam is more expensive than rolled fiberglass, and it’s definitely more difficult to install around obstacles or in odd-shaped spaces. Here are the three main types of rigid foam insulation:

  • Best – Polyisocyanurate (polyiso for short) foam has the highest R-value per inch (R-6.5 to R-6.8) of any rigid insulation. This type of rigid foam usually comes with a reflective foil facing on both sides, so it can also serve as a radiant barrier in some applications. Polyiso board is more expensive than other types of rigid foam.
  • Better – Extruded polystyrene (XPS) rigid foam is usually blue or pink in color, with a smooth plastic surface. XPS panels typically aren’t faced with other material. The R-value is about 5 per inch. This type of rigid foam won’t absorb water and is stronger and more durable than expanded polystyrene, so it’s probably the most versatile type of rigid foam. XPS falls between polyiso and expanded polystyrene in price.
  • Good – Expanded polystyrene (EPS) is the least-expensive type of rigid foam and has the lowest R-value (around R-3.8 per in.). It’s also more easily damaged than the other types of rigid foam.

One last thing I want to add. Seems like a fairly common practice is to use some type of radiant barrier insulation to deflect heat/cold and add R value. I’ve seen this listed as an option while watching videos during factory tours.

Thanks for reading and commenting.

4 thoughts on “RV Construction Methods – Insulation

  1. Mark, I’m also thinking of getting a 5er. Montana’s by Keystone seem like a good bet. But in the end we will buy used and will get what ever we find that is a good deal.


    • Bill, from what I’ve been reading so far, Montana by Keystone seems like a good all around rig. It’s a small detail but I saw one video where the entrance door would stay open in any position without having to open it all the way and hook it against the rig. I also like their ceiling design and their air conditioning setup. Lots more to like on a Montana. They would definitely be on our short list if we were to buy one today. I recall on your blog you mentioned the Montana which was the reason I kept a look out for them. At the Kansas City RV Show we spent a lot of time talking to their factory rep. Nice guy and he did not BS about anything. He even mentioned some construction methods are as good as the quality of the employee they hire to build them. He said everyone has issues with some employees so there can be problems with the rig. How true is that in about any business. I’m looking forward to taking a few factory tours. Thanks for always posting comments. I appreciate your feedback.


  2. Pingback: Heavier vs. Lighter Fifth Wheels | Our Future in an RV

  3. Pingback: Toured the Cedar Creek Fifth Wheel | Our Future in an RV

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