Question: What kind of floors do submariners walk on?
Answer: The subfloor, of course?
OK, to be honest I had no idea what a subfloor was when we started this whole extravaganza. Stef probably did, but unlike me she’s a real engineer :). I mean, as the name implies, I figured it had something to do with the floor, duh! For those of you who share my lack of understanding of construction lexicon, the subfloor is the floor that sits right on top of the frame and forms the support structure for putting down tile.
As it turns out, the subfloor also has a very important structural function in 1963 Airstreams. It’s kinda like the glue that holds everything together. The axle attaches to the frame. The frame attaches to the subfloor, and the shell attaches to the sub-floor.
I know what you’re thinking . . . “Hmmm . . . why doesn’t the frame attach to the shell?” (at least that’s what I was thinking). I’m not quite sure, but I think a partial reason was to minimize the effects of galvanic corrosion.
In nerd-eze, galvanic corrosion is the corrosion damage which occurs when two dissimilar are brought into electrical contact and the metal with the higher affinity for electrons takes them from the metal with the lower affinity. In this case, steel is a more noble metal compared to aluminum which means aluminum will give up its electrons which will travel through the steel preferentially looking for a place to oxidize a surrounding chemical.
Follow this link to learn a little more about the corrosion we found and what we’re doing about it:
The super awesome drawing below shows how that connection was made on this trailer, while the “as found” picture gives you a feel for what we found when we started looking at the screws holding everything together. The third photo shows most of the connection depicted in the drawing (missing the subfloor and shell). Nearly every one of the “fasteners” thoroughly corroded. Some simply snapped off when we started working them with vice grips. (Side note: I’m glad we made it to TX from Northern NM without anything really big coming off.)
Now, I know what you’re thinking. “Pete, what about the belly pan? That’s aluminum right? And it contacts the steel frame directly, right?” Good question. As it happens, belly pan aluminum is a more corrosion resistant (5052 H32 Aluminum in case you are taking notes.)
The subfloor came out relatively easily once we found all of the fasteners and neutralized them with extreme prejudice. The most challenging part was that original subfloor was replaced piecemeal and somebody had used a ton (I mean a s-load) of sheet metal screws to connect the “after-market, non OEM” subfloor to the frame. About 1 in 10 actually connected to something and the rest were safety hazards. (OEM = Original Equipment Manufacturer).
Under the subfloor we found another former rodent habitat. This one was more akin to a country villa complete with lounging areas and extra living space.
It’s interesting to note that since the trailer was permanently affixed as an apartment previously, it was hard piped to a septic tank. The “toilet” picture above shows where the toilet used to sit and the hole is where it connected to the septic tank piping. For a fleeting moment we contemplated going back with the “straight pipe” design and relying, instead, of parking over pre-dug holes or flowing bodies of water. 🙂 J/K.
Pete and Stef's 1963 Airstream rebuild 