Promaster Flooring Install

Insulation, Plywood, and Vinyl Floor Install in a DIY RV Van:

One of the first construction projects on our RV Promaster van was the flooring installation. We chose to install a floor consisting of one inch polyisocyanurate rigid foam insulation board (R-6), followed by 3/4 inch tongue and groove plywood, and then finished with a sheet of continuous vinyl flooring. Although we considered using sheep wool insulation, we decided this was not the best product for under a floor in an area that may gather moisture in some instances.

The first step was to create a full size patter of the van floor cargo area. We did this with a 36 inch wide roll of heavy brown kraft or construction paper. We cut and taped the paper until we had a large, one piece exact pattern of the floor bottom. This paper pattern was then laid over three sheets of the insulation board, and the pattern outline was traced onto the insulation board. We used a utility knife to cut the foam board to match the paper pattern.

Paper pattern placed on insulation boards

The foam insulation board was laid into the van floor cargo area and taped together with foil tape to secure it as one large piece. We marked the existing floor bolt threaded holes in the insulation. A second paper pattern was made to be the exact size of the top side of the insulation board. This second pattern was slightly larger than the first, since the plywood would be able to extend beyond the foam board, especially in the door entry areas. We also marked the factory bolt down holes in this second paper pattern.

Three piece insulation layer, taped with foil tape

We placed our three sheets of plywood tight against each other on a large open area and marked the outline of the second pattern and the bolt holes on the plywood. A jig saw was used to cut the plywood to match the pattern, and the bolt holes were drilled at the correct locations. All three sheets of the 3/4 inch plywood were primed on both sides and all edges with a quality primer. This would protect the wood from outside moisture.

The plywood pieces were placed on top of the foil insulation board in the van, and a few bolt were placed into the factory tie down holes to secure them in place. Extra holes were drilled in the middle area of the plywood floor and secured with countersunk M8 x 1.25 flat head bolts using washers and nuts below the metal van floor.

On the back entry door and side slider locations, a long piece of wood was cut to go in place of about 1 inch of foam board. This provided a solid exposed edge and protected the entry areas from flexing as people entered and exited the van.

Extra wood layer under the plywood on door entry edges

At this point, the plywood floor was nearly ready to install the sheet vinyl. The joints and any low spots, along with countersunk bolt heads, were filled and covered with a flexible filler product (see the list of products below). This was lightly sanded and the entire floor was wiped down with a damp rag and left to dry.

The plywood paper pattern was used again to mark and cut a large piece of sheet vinyl flooring that would be the finished floor in our DIY RV Promaster van. The flooring was test fit, and then 1/3 of the floor was covered in flooring adhesive with the proper sized trowel. Each section was smoothed out as it was glued to remove any air bubbles. After the entire sheet of vinyl was glued in place in the van floor, the edges were taped with painters tape and it was all left to dry.

Gluing the vinyl sheet flooring down 1/3 at at time

The final step to finish the RV Van Promaster floor was to cut and install vinyl stair edge on the side slider entry and rear door entry exposed edges. We decided the vinyl edge would be more forgiving and less slippery than an aluminum edge.

Vinyl stair edge glued and temporarily taped in place

We are quite pleased with the DIY RV floor finished look. It will provide a continuous water resistant surface under all tanks and cabinets as we finish the RV floor plan build out in our Promaster van.

Here is a list of the products and tools that were used for our RV flooring project:

We also have produced a Youtube video detailing the Promaster RV flooring install that provides more detail. Click the image below to view the video.

Happy trails…

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