RV Roof Replacement PART 4: Installation of New Roof Plywood

RV Roof Replacement Project

PART 4: Installation of new roof plywood

This was a big day for us. As I mentioned in Part 3, making the decision to replace the entire roof instead of the damaged areas was not a fun decision. We knew that it would require a lot of additional work, but we wanted to do it right as we had already come so far and really, REALLY did not want to do this again in a VERY long time. Since it would have taken a tremendous amount of effort to chisel away the entire roof from the Styrofoam insulation we decided to simply use liquid nails and screws to attach an additional 1/8" piece of plywood overtop the original 1/8" roof in the areas that were undamaged. We would then place TWO layers of 1/8" plywood over the areas that were completely removed. 

However, we ran into another hiccup: our local hardware store did not carry 1/8" plywood so we were forced to travel 3 hours roundtrip to one that did. We also purchased a product called "Great Stuff Pro Spray Foam Adhesive" that was recommended by someone on a YouTube video. It appears to only be available online, so we had to wait a bit for this one to come in before beginning the roof replacement.  Our plan was to use the great stuff to attach the new boards to the Styrofoam below (this product is Styrofoam safe!) and then use liquid nails for the rest. 

Great Stuff is kind of an expensive investment, as you not only need the product (roughly $17 a can and we used two for he two 4x8' plywood boards that were replaced) but you also need the gun ($50) and cleaner ($8). However, this product is absolutely terrific- you only have about a 10 minute window to apply the foam before needing to adhere the roof so you have to work quickly. 

Great Stuff foam being applied over the Styrofoam.

After placing the replacement board, we put some concrete blocks on top to press it down. We allowed the Great Stuff time to dry before starting the next layer. 

Using blocks to hold down board

We then moved onto the front of the RV. However, we unfortunately ran  into a MAJOR problem- because the original roof was so thin, when we were removing the damaged wood from the front of the RV the metal joist below gave way and the roof sunk about 3 inches down. Unfortunately, because the metal piece was attached to the inside of the ceiling, the only way we could fix it was by somehow gluing it from the top. This was the second time where we panicked, and almost gave up. However, after some time brainstorming ways to fix the collapsed roof we came up with an idea- we ended up spraying more of the amazing Great Stuff Pro (and no, I am not affiliated with this company but I cannot sing their praises enough!) by sticking the nozzle of the gun underneath the Styrofoam and then immediately running to the inside where we attempted to push up the roof from the inside by climbing onto the dropdown bed and pushing up with our legs. It was hilarious and was a LOT harder to hold to hold the position for 10 minutes than we thought, so we ended up rigging up a board to push it up.

Us, literally trying to raise the roof

A much easier solution

We left the board in place for several hours and hoped for the best. When we returned we discovered that it actually worked! The roof was no longer sagging and was now perfectly aligned on the top side. We then moved onto the new boards. 

After replacing the damaged areas, we began the process of replacing the wood on the rest of the roof. This process was actually fairly easy, because we simply laid the boards on top of the roof, drilled a hole, and then used a hand saw to cut out the openings. For the vents we used a special tool meant for cutting circles. 

Cutting out the new holes

We then covered the edges of the holes with aluminum foil tape- this was something we noticed was done on the original roof and since we didn't have a single leak to any of the fixtures we definitely wanted to do the same thing.

Foil tape on the new holes

We then added liquid nails to the old wood and quickly placed the new boards on top. We noticed that even though we were well under the 10-minute window of time that the manufacturer suggests, the glue was starting to form a skin very quickly. We did the best we could, but noticed that some of the areas did not feel like they were fully adhered to the wood below. For these spots we used a staple gun and placed as many staples as we could. We then added screws on each corner as a secondary measure. 

We then replaced the radius trim and used staples to securely attach to the sides, covering all seams with seam tape to soften the connection between the metal trim and the roofing below. 

Seam tape on edges

Roof is complete!

In hindsight I wish we had completed the entire roof with the Great Stuff  instead of the liquid nails. We were dismayed to find that the liquid nails did not adhere as well as the Great Stuff, and I believe that this was not necessarily the fault of the liquid nails. The Great Stuff, being a foam, sealed the gaps that were between the 2 layers of wood. Even though the 2 layers of wood were theoretically right on top of each other I feel like there was still a little bit of a gap between them. The liquid nails may have been too thin to grab onto both boards. As a result, we had to our a nail gun to staple the heck out of the boards, then used screws in every corner to hopefully keep the boards down. It wasn't what we wanted but in the end the roof felt a LOT more sturdy and we were incredibly proud of the result. 

Keep reading to see what was next!