New guy here needs floor advice.

[brian.christopher]

I just bought a 1978 28j that is rotten half way through the back bedroom. Does anyone have any info on rebuilding the floor? I want to see how everyone else is doing it but cant find info online.
Thanks.

[Razorback]

Welcome to the forum, Brian.

Someone will chime in here soon..... but I don’t have any experience there.

From what I know of the floors (and I need to look at a brochure for your year to see if they are the plywood/foam/plywood sandwich) and what I have heard others say, our Avions don’t require the shell to be removed to accomplish a floor replacement. It’s surely a tedious job, but not impossible.

Looking forward to hearing more about this.

[Rostam]

I have a 1978 26' Avion. It had floor rot in front (minimal) and rear (major). I thought about fixing the floor myself, but I neither had the tools nor the time for this job. So, I decided to contract it out. Initially, thought about taking my trailer to Cayo, but they are 12 hours drive away each way. So, I decided to find a local shop to do the work. I researched floor repair and wrote a document. I spent some time with Chuck Cayo on the phone verifying my approach, and then provided the document to a local shop which fixed my floor. I'm happy with the results. I am attaching the document below. I would not say the instructions are complete or 100% correct, but they should get you started. I would contact Chuck Cayo and Dr Gradeless with any questions. They are both very very helpful. Good luck!

Fixing the floor

There are 2 soft spots in the front and rear of the trailer.
The front soft spot is on the street side, under the dinette seat.
The rear soft spot is under the beds (both sides) and around the water heater.
You must remove the dinette seat to fix the front soft spot.
You probably must remove the rear beds, the night stand, water pump, and water heater to fix the rear floor soft spot.
Trailer floor is constructed in 3 layers: plywood, hard Styrofoam insulator, and then plywood.
Front soft spot is most likely top plywood layer only. Need to verify this.
Rear soft spot is most likely rotten down to the bottom plywood layer. Need to verify this.
The trailer frame and its cross members are under the plywood subfloor (see photo attached).
After removing the front dinette seat, carefully cut ONLY the top plywood layer around the soft spot.
Make sure you do not hit the frame or its cross members as your saw will be damaged.
Make sure you do not hit the 2 by 2 which supports the sub floor, as subfloor support will be damaged.
If the damage is top plywood only, replace the top plywood using exterior plywood – Please read the attached instructions.
The rear floor rot may be more severe; the bottom plywood may also be rotten.
Must verify this. If it is indeed fully rotten, the whole subfloor must be removed (top plywood, hard insulator, and bottom plywood). This exposes the frame. Please apply POR-15 anti-rust to frame and its cross members, per instructions provided. Also please use a shop vacuum to clean what is between the subfloor and the belly pan.
If the floor rot is deep, i.e. the bottom plywood is also rotten, there is no need to reconstruct the layered Avion floor (i.e. plywood, insulation foam, plywood). Just use enough layers of plywood (place them on top of each other) to form a thick enough floor. Use glue in between different layers of plywood sheets.
If completely replacing the floor (i.e. not just the top layer plywood, but the bottom as well), plywood must be attached to the frame.
Use screws to attach plywood to the frame or its cross members. Use glue to attach multiple plywood sheets you lay on each other to form a thick enough floor.
The floor patch should go under the wall. The old floor under the wall must first be cleaned up.

From Avion forum: There is a channel between the outer and inner skin fastened to the floor with staples and a bolt through the floor to the frame every other rib. The floor is solid plywood under the wall then changes over to a plywood/foam sandwich. If you are lucky the rot will be localized however I suspect you will find substantial rot around the perimeter. It all has to come out even the fasteners so the new floor can go under the wall to support the shell. If you don't pull the interior skin to replace the fasteners holding the shell to the floor you will have to fasten a piece of angle along the wall into each rib and through the floor to the frame.

[KYAvion]

From what I've seen of my own Avion and prior Airstream, the floor of an AVION is not an integral part of the shell to frame connection like is the case with an Airstream. That is, the subfloor of an Airstream sits BETWEEN the shell and frame, and therefore the shell has to be lifted slightly to install and secure a new subfloor.

However, I wonder if earlier years of Avions are like this?

Also, when redoing the floor, I'd recommend extruded polystyrene (not expanded polystyrene) for the foam inside layers of plywood to achieve the highest R value possible.

[brian.christopher]

Thanks guys.
Rostam you saved me a bunch of time. I had my theories from the old stuff that I’ve seen while cutting out the floor. We have the same rot in the same places.
I saw the staples, while I removed the old bolts. Do these need to be beaten back or replaced before the new floor goes in? It would make sliding the floor under the wall a lot easier.
Also the c channel thing is important. I saw the flat floor bolt, but wasn’t sure if they were holding the wall up or the floor down.
Also the top plywood looked to be 3/4” but online I see they’re saying it’s 1/2” what’s the deal with that?
Thanks again.

[Sawmiller]

I removed and replaced the entire floor on my 68. I milled solid wood boards with a deep toung on the outside edge to attach the plywood sheets. These were placed under the walls then bolted and screwed to the frame. Next I slid in the bottom plywood and screwed it in from the top of the tongue pulling it up. Added wood strips over the bottom ply, the same thickness as the insulation, and used large self tapping screws to attach to the frame members. Then the top ply was added.

I then used a heavy 1.5 X 1.5 aluminum angle around the entire interior wall area, except for the wheel wells. Pre drilled holes then screwed it to the walls and floor.

I also put multiple coats of tan oil based paint on the solid wood members that fit under the walls.

Put about 2000 miles on it so far seems solid as a rock.

[brian.christopher]

That’s awesome. So the angle screwed to the walls and floor takes the place of the bolts that are under the walls?

[brian.christopher]

Saw Miller, did you bang the staples back or remove and reinstall them?

[Sawmiller]

Yes. The stainless steel screws attach low on the walls and go into the the floor rib, wall ribs, and wall sheeting . I cut the staples with a dremel and a right angle grinder with a thin blade. I also removed the belt line trim. The trim, at least on mine, screws to the side of the floor from the outside. Had to jack up the shell a bit with t posts because all of the interior support was removed. It made it easy to slide the solid wood pieces under the walls. If most of the interior is intact jacking will probably not be necessary.

Also had to notch the cabinetry and bulkhead walls to go over the aluminum angle. 95 percent of the angle is covered by cabinetry etc.

[osullivan]

Are you saying in order to deal with the rotten wood under the exterior walls you have to remove the exterior rub rail and then all the staples also? And when you say jacked up what and how did you jack up?

Thanks ds