What You Need to Know Before Starting

Replacing a camper floor is a project you can do yourself if the damage is limited to one section and you have basic carpentry skills. Most RV floors fail because water has rotted the plywood subfloor underneath the vinyl or carpet—the visible surface often looks fine while the structure underneath is soft. Before you tear anything out, you need to know how far the rot extends, what material the original floor is made of, and whether you can access the underside of the RV. If rot has spread to the frame or walls, or if your camper is a newer model with a glued-down floor, this becomes a job for an RV repair shop.

The basic process is the same whether you are patching a 2-by-3-foot section or replacing the entire floor: cut out the damaged area, remove any wet insulation underneath, install new plywood and insulation, seal everything against moisture, and install new flooring material on top. The whole job takes three to five days for a partial replacement, longer if you are doing the entire floor. You will need to work in dry weather and have the camper parked on level ground with good access underneath.

Key Takeaways

  • Water damage to camper floors usually starts underneath the visible surface, so probe the plywood with a screwdriver to find the true extent of rot before you start cutting.
  • You will need to remove the old flooring, cut out the damaged subfloor, replace the insulation, install new plywood, seal all seams, and install new flooring material—each step must dry completely before the next one begins.
  • Camper floors are typically 1-inch thick (½-inch plywood plus ½-inch insulation), so measure your original floor thickness and match it exactly to avoid creating low spots or high spots.
  • The most common mistake is skipping the moisture barrier or sealing step, which causes the new floor to rot in the same spot within two to three years.

Identifying How Much Floor Needs to Come Out

Start by finding the edges of the rot. Use a flathead screwdriver or awl to probe the plywood around the visible soft spot, pressing hard enough to puncture the surface. Solid plywood will resist; rotted plywood will feel spongy and the tool will sink in easily. Mark the perimeter of the soft area with a marker or tape, extending at least 6 inches beyond the last spongy spot in every direction. This margin matters because rot spreads invisibly through the wood grain, and leaving even a small pocket of wet plywood will cause the new floor to fail.

If the soft area is larger than 3 feet in any direction, or if it extends to within 12 inches of a wall or cabinet, consider whether you have the skill and time to do this yourself. Large patches require careful framing to support the edges of the new plywood, and patches near walls risk damaging plumbing or electrical lines that run underneath. If you are uncertain, take a photo and email it to a local RV repair shop—most will give you a rough assessment for free.

Removing the Old Flooring and Subfloor

Start by removing the flooring material (vinyl, carpet, or linoleum) from the damaged area. If the flooring is glued down, use a heat gun to soften the adhesive, then peel it back slowly. Work from the edges toward the center, and be patient—rushing will tear the material into small pieces that are harder to remove. Once the flooring is off, you will see the plywood subfloor. Mark your cut lines with a straightedge and pencil, making sure the edges fall on solid wood at least 6 inches beyond the rot.

Use a circular saw or jigsaw to cut out the damaged section. If you are cutting a rectangular patch, make your cuts perpendicular to the floor joists (the wooden beams underneath) so that the edges of the new plywood will rest on solid framing. Once you have cut through the plywood, pry out the damaged piece with a pry bar. You will likely find wet insulation underneath—remove all of it, even the parts that look dry. Wet insulation loses its R-value and traps moisture against the new plywood you are about to install.

Installing New Insulation and Plywood

Before you install anything new, let the cavity dry completely. If the wood underneath is wet, use a shop fan or hair dryer to dry it out. This step takes longer than you think—at least 24 hours in dry weather, longer if humidity is high. Do not skip this. Moisture trapped under new plywood will cause mold and rot to return within months.

Measure the thickness of your original floor. Most camper floors are 1 inch thick total: ½-inch plywood on top and ½-inch foam insulation underneath. Some older models use ¾-inch plywood. Match this thickness exactly. Install new foam insulation (XPS or polyiso foam board, ½-inch thick) in the cavity, cutting it to fit snugly. Then cut a piece of ½-inch exterior-grade plywood to fit the opening. The plywood should rest on the floor joists and sit flush with the surrounding floor—no gaps, no high spots. Screw the plywood down with 1¼-inch deck screws spaced 6 inches apart around the perimeter and every 12 inches in the middle.

Sealing Against Moisture

This step determines whether your repair lasts five years or fifteen. Once the new plywood is screwed down, seal all the seams and edges. Use a waterproof caulk (polyurethane or silicone) to seal where the new plywood meets the old floor and where it meets the walls or cabinets. Also seal the screw holes. Let the caulk cure for 24 hours before moving on.

Next, cover the entire patched area with a moisture barrier. The standard choice is 6-mil polyethylene sheeting, taped down with waterproof tape. Overlap the barrier 12 inches onto the surrounding floor and tape all seams. Some RV owners use a liquid moisture barrier instead (a paint-on product), which works well if you explore it in two coats and let it cure fully. Either way, this barrier stops water from reaching the new plywood if a leak happens above.

Installing New Flooring Material

Once the moisture barrier has cured (24 hours minimum), you can install new flooring. If the surrounding floor is vinyl, match it as closely as possible—take a sample to a flooring supplier and ask for a close match. Vinyl flooring for RVs comes in rolls or sheets; ask the supplier to cut a piece slightly larger than your patch. Use a vinyl adhesive recommended for RV use (not standard floor adhesive, which can off-gas in the heat of a camper). Spread the adhesive with a notched trowel, then lay the vinyl and roll it firmly with a hand roller or J-roller to remove air bubbles.

If the surrounding floor is carpet, you have two options: patch with matching carpet (difficult to blend seamlessly) or replace the entire floor covering. Many RV owners choose to replace the whole floor with vinyl when they repair a section, because a carpet patch is visible and traps moisture. Vinyl is easier to clean, more durable, and better for moisture control in an RV.

Common Mistakes to Avoid

The most frequent error is not removing all the wet insulation. Owners see that the plywood is soft and cut it out, but leave insulation that looks damp but not soaked. That insulation will trap moisture against the new plywood and cause rot to return. Remove every bit of the old insulation and let the cavity dry completely before installing new material.

The second mistake is skipping the moisture barrier or caulking step. A new floor installed directly on plywood without a barrier will absorb moisture from any leak above and fail within a few years. The barrier is not optional—it is the difference between a repair that lasts and one that fails. The third mistake is not matching the floor thickness. If your new floor is thinner or thicker than the original, it will create a lip or a dip that catches water and looks wrong. Measure twice and cut once.

Frequently Asked Questions

How do I know if the damage is too big for me to handle?

If the soft area is larger than 4 feet in any direction, or if it extends under cabinets or walls, take it to a shop. Large patches require temporary support structures while you work, and damage near walls risks hitting plumbing or wiring. A shop has the tools and experience to handle these safely.

Can I just cover the soft spot with new flooring instead of replacing the subfloor?

No. The rot will continue to spread underneath the new flooring, and the soft spot will collapse under your weight within weeks. You must remove the damaged plywood and replace it. Covering it is a temporary fix that makes the problem worse.

What if I find mold under the floor?

Mold indicates that moisture has been present for a long time. Remove all affected material, let everything dry completely, and treat the wood with a mold-killing primer before installing new insulation and plywood. If mold covers a large area or if you see it on the frame, call a professional—mold in an RV can be a health hazard and may indicate structural damage.

How long does the whole repair take?

A small patch (under 2 square feet) takes two to three days if weather is dry. A larger section takes four to five days. Most of the time is spent waiting for caulk, moisture barrier, and adhesive to cure. You cannot rush these steps without risking the repair.

What if water is coming from above, not from underneath?

Fix the leak first. If water is dripping through the floor from a roof leak or window seal failure, replacing the floor will not solve the problem—the new floor will rot the same way. Find and seal the source of the water before you start the floor repair.