RV underbelly magic : Coroplast

A Plastic material that is very similar to cardboard

Many people wonder what the material is that covers the underbelly  of an RV.

The story is actually interesting, and certainly not consistent across the board.

Our first RV, Puma, was a bit of a wreck underneath. I’m pretty sure it was some insulation and then a thick plastic, like 6 mil. For something rolling down the road this doesn’t seem like a very good plan.

Our second RV, an Open Range 399BHS, marketed itself as a “four season” RV. Personally, that “four season” nomer seemed like a bit of a stretch to me, but maybe the four seasons were somewhere in Texas, Arizona, and Florida.

However, I do think that at that time Open Range DID do some extra thinking on how to make their towables withstand colder weather better. For example they did insulate spaces that might normally be ignored and they allowed heated airflow in those places. It has been a little while, but if memory serves me the heater would heat the area where the holding tanks were. While taking marginally more energy it would keep the holding tanks from freezing.

Sheri and I lived in the Open Range through three Texas Winters (please don’t make fun of us you Michigan RVers) and in one winter and I’m not kidding, we had 30 straight days of freezing temperatures. With the exception of the water hose between the RV and the shore water hydrant, the Open Range did very well.

Which brings me to Coroplast.

When I looked underneath the Open Range, it had a very strange material underneath it. This material covered the underneath in a very similar way to thin sheets of cardboard. What you would see is the big 4×8 sheets of this material and it would bow slightly in the middle where it wasn’t secured with any bolts.

All along the edges of this material you would see self tapping screws with large washers. While plastic never seems like the best material, I can see that this special plastic has many many positive attributes that you can’t quite get with any other material.

For example, while metal sheets seem like something superior, they too will bow if you use thin material and if you make them thick material, then metal is heavy. Plus you have the added disadvantage of rust.

Plastic rolled sheeting like the 6mil thick, I’m not going to spend time here since it should be obvious that one small stick in the road and you tore the coating completely off.

So honestly, from a RVer standpoint, I would have to really agree that the RV underbelly material like Coroplast is a wonderful thing to protect your RV.

Here are some the neat advantages of the corrugated plastic for RV underbelly:

• Very lightweight.
• For its weight, it is amazingly strong thanks to the corrugation.
• It is waterproof. It is plastic for crying out loud. Water is no problem. NOT TRUE with metal or wood.
• It is tough. Maybe not as tough as metal or wood, but it is pretty tough.
• It is economical to replace (you can buy online really easily – see below)
• You can cut it and shape it.
• You can use screws with washers to fasten it in place and it won’t tear out easily.
• You can remove it and put it back up – it is durable enough that you can use it over and over again.

If you look at this plastic cardboard, it looks exactly like cardboard. But it clearly is a material that is waterproof like plastic. Well, it IS plastic.

The material is called Coroplast and you can find a manufacturer of it here (  http://www.coroplast.com )

Check the RV52 RV Parts Database for coroplast if you ever want to replace or place on your RV underbelly: