RV Floor Replacement Project Part 4: Assembling the New Floor

RV Camper Floor Replacement Project by Rick Kessler Jr.

Author's note: I wish I could post all of the photos I took as I did this project. However, I took them with my iPhone and left it out in the rain. It completely fried the phone to the point two different stores couldn't even bring it back to working order, let alone retrieve all the photos. I'll do my best to describe everything, but I'm afraid I have no pictures. I created some diagrams in the Scribd file above and inset into the post below to further try to explain all that I did.

Click here to read Part 1: Admitting the Problem Exists
Click here to read Part 2:  Realizing the Scope of the Problem
Click here to read Part 3: Deconstruction

Figure 1; the break in the metal cross beam was located right on the trailer frame near the door

Part 4: Assembling the New Floor

You can see a video of the project, including the layout of our camper, by clicking here.

As I said in the last post, during demolition I discovered one of the metal cross beams had cracked near the door (see Figure 1). This caused the wall on the door side to sink about an inch or so, which meant the dinette and cabinet previously attached to that wall had separated from it.

Fixing this became my first priority.

A quick trip to the local big box home improvement store (Mr. Lowe's, if you want me to mention your store by name you'll have to pay me!), netted me a 3-foot length of angle iron along with some lag bolts. I used a jack from my TrailBlazer to lift the sagging wall so the cross beam was level. One foot of the angle iron covered the cross beam from the crack to the wall, and the remaining two feet extended out into the middle of the camper. Two bolts through the angle iron and cross bream on each side the crack secured the angle iron, and newly leveled cross beam, in place. Good as new!

With that repair over, it was time to make sure the rest of the camper was primed for the new floor. Utility knife cut away any leftover flooring.

Using Bill Debs' experience with his floor project as a guide (thanks again Bill!), I took my measurements, bought the materials and transferred my base of operations to my garage. Why? I needed the large level floor of my garage to make sure my new RV floor would be completely level. I couldn't be certain the floor would be level had I assembled it in the camper. Actually, I was fairly certain that had I done it that way, it would have been very un-level.

Figure 6

As for the actual floor assembly, here's what I did (see Figure 6):

1. Cut and laid the 1/4-inch luan plywood on the floor.
2. Cut and laid 2x4s on their widest side on top of the luan. The 2x4s would serve as additional cross beams since there was only the single metal cross beam for the entire interior floor space of the camper. 
3. Cut and laid 1 1/2-inch foam board in between the 2x4s.
4. After I was satisfied everything dry-fit well, I glued everything. Make sure you use glue that won't deteriorate the foam board.
5. Stacked anything and everything I could find on top of the assembled floor so there would be a solid bond after the glue dried.
6. The following day I flipped the assembled floor over and installed Owens-Corning Ice Guard on what would be the underside of the floor. The Ice Guard is basically rolled roofing material, with one side pre-glued so that it stuck to the underside of the camper floor. This would serve as my undercoating. I used screws to further secure the Ice Guard to the plywood, and the plywood to the 2x4s.

NOTE: While the plywood was cut so it would extend from one wall to the other, the 2x4s and foam board were not. These were cut short to leave room for a 2x2 on each end. The 2x2 was not part of the pre-assembly, however.

NOTE II: I had to assemble my floor in two pieces. One full piece would not have been able to slide under the door threshold and the kitchen cabinets. This ended up causing some issues during installation, but the end result is all good.

NOTE III: In hindsight I would not have used 1/4-inch luan plywood. I would have used 1/2-inch, or even 3/4-inch, treated plywood. I would have used thinner foam board to compensate for the difference so my new floor would be the same thickness as the old floor. I actually had bought 1/2-inch treated plywood but returned it and went with the luan instead. At the time, I figured that's what the factory used so I should do the same.

Next -- Part 5: Installing the New Floor.