Airstream Shell On Floor Replacement: Part Two

When we last left off, my Airstream was floorless and, admittedly, looking rather sad. So, in this post, I will show you how to complete that Airstream shell on floor replacement.

Step One: Repair the Frame

After removing the floor, we discovered several locations where the frame required repair. I wouldn’t say the frame was about to disintegrate before my very eyes, but it was pretty clear some sections needed to be replaced,  primarily in the front and rear of the trailer. (The same areas where the subfloor was in poor condition.)

If your frame is in simular condition, purchase some new steel, pay a welder if necessary, and bing-bang-boom new frame!

In reality, the process more complicated than that. But now our frame is in much better condition.

Step Two: Prevent Further Rust Development

The rest of the frame was in good condition, but we wanted to prevent further deterioration. To do this, wire brush the frame to remove loose rust then apply a coat of POR-15 or simular product.

POR-15, which we lovingly refer to as tar, is a product which chemically bonds to the rust and prevents further rust development. Fair warning, it’s strong stuff so avoid getting it on your skin (it will be there for weeks) or the lip of the paint can (you won’t get it open again).

I also recommend giving the ground a squirt or two with the hose after painting POR-15 if you live in a dry climate like me as moisture helps POR-15 cure.

Then, since any new steel (hopefully) won’t be rusted, paint that with a coat of rust-preventative paint like Rustoleum.

Ultimately, this is the very fun step when you’ll realize just how many surfaces the frame has.

Step Three: draw a subfloorplan

Each Airstream model and size will have a slightly different subfloor layout. To make sure you know yours, draw a plan of the pieces. To determine the correct layout, you can either reference the original floor pieces or measure the frame. Wood is generally sold in 4′ by 8′ sheets, so any frame members 4′ apart will require one sheet of plywood.

For our airstream, we bought 7 sheets of 1/2″ ACX plywood. Our layout required two 2′ wide pieces, which we chose to cut from the same sheet, and one 3′ piece. Some Airstreamers recommend marine grade plywood for the subfloor, which is superior to ACX, but it was more than double the cost. Therefore, we opted for ACX.

Step Four: Cut and waterproof Wood

With your plan in hand, cut the wood to size. This is a relatively simple step, with the exception of the rounded pieces. If your floor was in good enough condition, you can use the old pieces as templates. If not, you’ll have to employ some educated guessing.

Our trailer’s wood was in moderate condition. Thankfully some of the curved edge was intact and so I essentially played connect the dots and verified my educated guesses with some measurements from inside the trailer.

After cutting the wood, give it a good coat of a waterproofing solution. Don’t forget the edges!

Step Five: Insert Floor

Fair warning, the photo you are about to see is rather disturbing. Viewer discretion advised.

Remember how I advised you to insert shims into the c-channel to prevent it from bowing out? This is the reason I said that.

For some unknown reason, the streetside of the Airstream remained solidly on the frame, but the curbside wanted to bow out. We tried multiple times to force it back onto the frame, but eventually it would pop back out. So, we chose to use this problem to our advantage.

There are two ways to reinsert the wood. The first, which is more common, involves cutting each panel down the middle and inserting each half into the c-channel. Some force may be required to make the two panels lie flat on the frame if you make them rather tight. This is an adequate method if you don’t have any other options, but I was a little hesitant about it.

I’m not an engineer by any stretch of the imagination, but I was concerned that piecemealing the floor like that could cause problems down the road. So, we took advantage of the bowing problem. To insert the floor our way, you will have to let (or force) one side of the Airstream shell  to bow out. Then, slide one side of a full sheet of wood into the side of the c-channel which isn’t bowed out. (The last piece will likely be the hardest to insert and may require more fanangaling.) When all the floor is in, enlist a team of friends to help push the bowed c-channel back onto the frame, inserting the wood at the same time. It will be necessary to insert some of the bolts (see next step) while deadlifting the Airstream.

Step Six: Secure the shell to the frame

Next, secure the shell to the frame through the c-channel. Once more, there are two ways to do this.

As you might have noticed, we ultimately chose to remove the underbelly skin. Our underbelly was not in the best condition. In addition to large holes which could be patched, we noticed small pinholes. Since these would only expand over time, so we chose to remove and replace the aluminum. Without the underbelly skin, we could bolt the floor through the c-channel like the factory did. If you would like to use bolts like the factory, it is not difficult to drop just the sides of the underbelly for access. They’re held on with pop rivets.

If you removed the underbelly, purchase stainless steel bolts and lock/stop nuts. We bought a pack of 50 each and had plenty left over. We chose to drill holes up through the wood using the existing holes in the frame as a guide. Then, with a partner, insert the bolt from the bottom and screw on the nut from the top.

If you did not remove the underbelly, purchase stainless steel lag screws and use those to secure the shell to the frame through the c-channel. Because we replaced the rear frame with new, closed steel tubing, we had to use lag screws to secure the rear of the trailer.

Step Seven: secure the subfloor to the frame

To secure the subfloor to the frame, you will be replacing the screws you removed. I purchased 125 floor repair screws from Vintage Trailer Supply. These are self-tapping screws, which will help them stay secure as the Airstream rattles down the road. Originally, I tried to use the same holes because I didn’t want to drill more holes in the frame. But, I discovered that the old holes were slightly too big to properly secure the screw.

So, predrill new holes evenly spaced between the old ones, slightly smaller than the screw. If you have a fancy countersinking bit, use that to countersink the screws and ignore my next instructions. (Free tip: the high speed setting on the drill is best for drilling through the metal frame.)

If you don’t have a countersink bit, then use a drill bit the same size as the screw head next. This will allow the screw head to sit flush with the floor. Drilling to the right depth may take some trial and error. Although the Vintage Trailer Supply website says the screw will countersink itself, I found they needed some help.

Finally, change to a driving bit and the high torque setting, which will make it easier to tighten the self-tapping screw.

Just 124 left to go.

Step Eight: Walk around like a normal person again

I honestly had no idea how nice floors were until we didn’t have one. We were either balancing on the frame or clambering over it for months while doing this project.

The official Airstream inspector was also ecstatic about our progress.

Now, dust off your hands and take a moment to lay down on your new and improved subfloor. You deserve it.

More updates and how tos coming, so stay tuned!

Airstream Shell On Floor Replacement: Part One

In this post and the next, I’ll show you how to complete an Airstream shell on floor replacement. While a shell off floor replacement makes the labor of removing and replacing the floorboards easier, it can be difficult for DIY-ers with limited space or experience. So, here’s a step-by-step explanation of how we removed the floor before replacing it.

Step One: find an airstream with a rotten floor

This step isn’t too hard. I promise you. I tried to avoid buying an Airstream without rot, but somehow managed to do it anyway.

Your rot might be obvious, like this hole in our floor. (For the record, the previous owners screwed plywood over it when we purchased Nellie. Plus, I made the hole bigger. You know, for fun. So, it wasn’t as obvious when we bought her as it is now.)

But, you also might have sneaky rot. This is the stuff I found when I removed the interior furniture.

This is the rot that hides in the c-channel.

This is the rot that warps boards, eating them from the inside.

Beware the rot.

Step two: cut around the screw

To do this, I obtained a corded drill with a hole saw attachment. My father removed the pilot bit so that I would not drill out the head of the screw. However, without the pilot bit, the drill had difficulty staying centered. Therefore, I recommend taking a wide stance, squatting, and bracing your elbows on your knees. This will help control the drill, especially if you’re small like me.

If the wood is rotten, the drill goes straight through the wood like butter, but, if it’s not, the drill might want to migrate elsewhere.

In this second case, it is even more important to brace yourself to get a cut and prevent the drill from harming you or anything around you.

Finally, I found bracing myself was also important in case the saw struck the frame. The drill would twist out of my hands. Alternatively, you can mark the plywood depth on the side of the hole saw to prevent striking the frame.

Step three: Break the wood around the screw

Technically, you could do this after drilling around all the screws, cutting the bolts, and removing the wood; but, I found it useful to lever the flathead screwdriver against the side of the hole.

Your goal here is to break away most or all of the wood. Essentially, you need to clear the head enough to grip it.

Step Four: use vise grips to remove the screw

If you don’t have a pair of vise grips, get them. They’re great. They are a combination between pliers and a vise, which means they increase the force of your grip. Great for rusty screws.

I accidentally broke the head off one or two screws instead of completely removing them.

Step Five: Take a break to pet the dog

You won’t be able to continue if you don’t.

Step six: do the rest of the trailer

All 120 screws…

Step seven: Cut the elevator bolts

Ah…the elevator bolts. These are the most difficult part of this project and the aspect which waylaid our progress for months.

The elevator bolts are situated inside the c-channel and they bolt the frame to the shell through the wood. They are difficult to remove for several reasons. First, they were bent over in the factory to prevent them from coming loose during travel. Spencer actually managed to break off the top of a few bolts and unscrew the nut using vice grips. Ultimately though, that method was difficult, slow, and eventually abandoned.

Secondly, the lip of the c-channel prevents the bolts from being cut directly underneath the nut, as is the normal strategy for cutting bolts. Instead, we ended up making plunge cuts into the wood using a grinder or a cut-off wheel attachment.

This is where you might have to get creative, root through your tools, and find something that will work for you. Don’t forget to cut the screws/bolts in the door threshold.

Step Eight: Cut the wood in half

This step isn’t too bad compared to that last one. Grab a circular saw and set the blade depth to the depth of the wood, maybe a little bit less so you don’t hit the frame. Some Airstreams have a 5/8” floor. Ours had a ½” floor. Make sure you measure on a visible opening before cutting.

Then, make a plunge cut down the center of your first board. I started with a smaller, 2’ one.

Step nine: attempt to remove the wood, realize you missed some screws

After you’ve made your cut, you can lift out one half. Because I set the circular saw slightly shy of the wood’s depth, I needed a crow bar to lever one side and break it loose. The screw holes came in handy here.

At this point, my dad tried to manhandle the wood and yank it from the c-channel. Turned out there were still several small wood screws holding the wood in, so he accidentally bent the c-channel upward. So, you know, maybe don’t do that.

Instead, revisit the entire c-channel and use the same tools to cut those tiny screws as well. They might be more difficult to find than the bolts. In our trailer, the heads were practically melted by rust.

Repeat these steps for all the panels throughout the Airstream. You may be able to slide out the rounded end pieces intact with some fancy maneuvering, allowing you to use them as templates.

And that’s pretty much how you remove the floor from an Airstream with the shell on. But, before I go, one last piece of advice. I recommend inserting small pieces of wood throughout the c-channel as shims. They’re best placed at locations where the frame meets the c-channel. This will help the c-channel remain uncrushed by the weight of the shell and prevent it from slipping off the frame as it becomes untethered.

So, there you go, that’s how to remove the floor for an Airstream shell on floor replacement. Next week, I’ll show you how to replace it.