When people talk with me about their greatest fear regarding the purchase of a vintage travel trailer, inevitably the sub-floor and water damage come up. And with good reason! This is the literal ground you walk upon, the foundation upon which the interior is built, and in the case of Airstreams, a structural component.
Rather uniquely, an Airstream is comprised of 4 main parts. You have the trailer frame to which the axels are attached, the subfloor, the ribs (arching frame), and the skins. You take away any one of these components and you have a structurally deficient trailer. The aluminum skins hold the ribs in place with rivets, the skin/ribs are attached to the frame, trapping the subfloor in between. Lost yet? Its ok. My point... the subfloor is important and unfortunately, rather susceptible to water damage.
As I've previously mentioned, in all three of our renovations, once we peeled back whatever carpet or wood flooring was in place, we found rotted subfloors. Although each Airstream varied in the extent of damage, they all had damage. So what are we to do? You can do what one of the previous owners of the 1985 34' Airstream did and just layer a fresh piece of plywood over the top...
Or you could frame out some supports that press directly on the belly pan (1 thin piece of metal away from the ground below) to fill in the rotted hole and lay some wood floors over top...
On second thought, let's not.
So... what's the solution?
I already know I will get some dissenting opinions out there on my methods and techniques, and that's alright. Regardless, I am going to show you a solution that has worked amazingly well to fix rotted sub-floor on a shoe-string budget. Here we go.
1. Locate the metal frame studs underneath the floor.
This can be accomplished several ways. If you rot is extensive enough, just look through the hole. Otherwise, pick yourself up a stud finder. If all else fails, work in small pieces and remove the rotted wood until the frame is viewable.
2. Map out of nearest framing that effectively surrounds around your rotted section.
Sometimes this can be a rather large area. Don't cut corners, remove all the degraded wood as possible. Use a straight edge to mark the underlying frame in the center of the stud. Framing is typically 2" wide so marking a 1" from the edge should put you dead center.
3. Cut back the sub-floor to obtain fresh edges over these supports.
Take a Skill Saw set to the depth of the flooring and follow the lines you previously drew. At this point you should have clean edges with good quality subfloor splitting a frame stud. It is very likely you will have decades worth of rotted insulation underneath. Grab yourself a shop-vac and clean it out. Oh, and wear a mask!
4. Fill in the voids with new insulation.
Especially here in Texas, it can get a little warm and cold. You want to maximize your Airstreams ability to stay in the fight, give it a little help with new insulation.
4. Measure and cut a new piece of treated plywood (5/8").
You'll want this to be cut a precise as possible. You are looking to get as much wood on the lip of the frame as possible, along every edge.
5. Secure with self-tapping metal/wood screws.
Pretty self explanatory. Just go around and secure in your new subfloor pieces to the frame. I prefer Everbilt #10 Self-Drilling Wafer Head Screws, but to each their own.
And that's that. You'll find that in place to completely removing the shell, hoisting the shell and replacing the subfloor as a single unit, this is a fairly practical solution to those smaller rot areas.
Feel free to contact me with any questions or problems you may encounter on your own renovation! Thanks for reading.
'Beard' is an adventurous spirit who renovated his first Airstream in 2016 and has since renovated 2 more. He has a love for travel, science, music and his dogs. Beard is a drummer, Game of Thrones fanatic, Ph.D., outdoorsman, loving husband and neighbor.