I recently purchased a very well maintained 2002 5th wheel Mountaineer by Montana. I a going from a newer travel trailer (Jayco) tag 2007 but the Mountaineer is extremely well kept and passed RV friend's dealership maintenance checklist. Wanted a fiver but did not have the funds for a newer one. I love the unit and am looking forward to taking it for our first trip. The only thing that jumped out at me was the underside of the RV was not enclosed like my jayco and other newer models. I'm guessing the newer covered units if for insulation from cold weather or critters. Recently camped next to same model but a 2006 and it was completely covered underneath. I guess there is insulation between the metal/vinyl and the bottom of the trailer. Has anyone ever noticed this? I wonder if I could get someone to retrofit a cover for the bottom and what type of insulation should I use. Any reference sources would be appreciated.

The material used is Coroplast. That link will give you the distributors in your area. It's reportedly expensive. I've heard that Home Depot and probably Lowes can special order it. There is some special tape they use on it as well. Call Coroplast and get the product id for RV underbellies as well as the part number for the tape.The best insulation is rigid foam board, the 2 inch material. You can get that at Home Depot/Lowes as well. The RV manufacturers use fiberglass insulation which is fine until it gets wet when it is no longer and good. The rigid foam survives a water leak with no problems. BK

Most low end trailers dont have the bottom covered.

Seems strange to me that it was not enclosed. Look at the frame and see if you have any holes where screws may have been. That would indicate that it once had a cover but removed. I would be concerned traveling in wet conditions and water getting everything wet underneath.

Actually Coroplast is inexpensive, it is used for outdoor signs. Some yrs ago, I removed the factory plastic liner type underbelly and replaced it with 8mm thick Coroplast. Used 4x8 ft sheets and 'H' trim and installed one section at a time. Each sheet was about $10 as I recall.

Can't imagine any building material used on an RV being referred to as "expensive".B.O.

enclosed underneath of camper | Good Sam Community

Dayle1
Explorer II
Oct 23, 2013
agesilaus wrote:
blkdodge wrote:
Just called a deal here in Az and they sell it for $12.00 a 4X8 sheet.
Might be cheaper in other parts of the US.

Excellent, that's not a bad price.

On a typical 32 ft fiver you really only have about 24 ft of area to cover from the back of the storage compartment to the rear bumper. So that is just 6 sheets, but more likely 8 sheets if you want the joints to line up with the frame cross members. Most popular thickness is 4mm and what some RV manufacturers use, 8mm will cost a little more, but is more rigid and easier to use for DYI installation.
Vulcaneer
Explorer
Oct 23, 2013
Pretty sure that trailer had an enclosed underbelly when new. I had an 06 Copper Canyon. A Keystone lesser cousin to the Mountaineer. It had an enclosed underbelly. i'll bet you can find holes in the frame where the self-tappers were used.

And it should be enclosed, by all means. So get it done, as soon as possible. Keeps all the bad stuff out...mice, road water, bugs, etc.
Old-Biscuit
Explorer III
Oct 22, 2013
And a good friend to help hold in place while attaching screws.

Use some aluminum backed bubble insulation..Reflectix carried at Lowes.
laknox
Nomad
Oct 22, 2013
blkdodge wrote:
Just called a deal here in Az and they sell it for $12.00 a 4X8 sheet.
Might be cheaper in other parts of the US.

OP just needs a box of self-tapping sheet metal screws, a roll of Eternabond or Gorilla tape, a box cutter and straight edge, and he's good to go. :-)

Lyle
avvidclif1
Explorer
Oct 22, 2013
Dayle1 wrote:
Actually Coroplast is inexpensive, it is used for outdoor signs. Some yrs ago, I removed the factory plastic liner type underbelly and replaced it with 8mm thick Coroplast. Used 4x8 ft sheets and 'H' trim and installed one section at a time. Each sheet was about $10 as I recall.

What do they call that liner Crossroads uses????
agesilaus
Explorer III
Oct 22, 2013
blkdodge wrote:
Just called a deal here in Az and they sell it for $12.00 a 4X8 sheet.
Might be cheaper in other parts of the US.

Excellent, that's not a bad price.
blkdodge
Explorer
Oct 22, 2013
Just called a deal here in Az and they sell it for $12.00 a 4X8 sheet.
Might be cheaper in other parts of the US.
B_O__Plenty
Explorer II
Oct 22, 2013
Can't imagine any building material used on an RV being referred to as "expensive".

B.O.
Dayle1
Explorer II
Oct 22, 2013
Actually Coroplast is inexpensive, it is used for outdoor signs. Some yrs ago, I removed the factory plastic liner type underbelly and replaced it with 8mm thick Coroplast. Used 4x8 ft sheets and 'H' trim and installed one section at a time. Each sheet was about $10 as I recall.
Charlie_D_
Explorer
Oct 22, 2013
Seems strange to me that it was not enclosed. Look at the frame and see if you have any holes where screws may have been. That would indicate that it once had a cover but removed. I would be concerned traveling in wet conditions and water getting everything wet underneath.