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Old 05-05-2017, 08:17 AM   #1
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1968 26' Overlander
Bonnington , British Columbia
Join Date: Mar 2017
Posts: 10
HELP! Replacing the sub floor leaving the shell on

We're about to replace the sub floor of our '68 Overlander, leaving the shell on and just wedging under the shell and the C channel ( or is it called the U channel?)
Any tips or advice would be so appreciated. I've done some research and I came up with two posts, one the job stopped half way through and the other one is informative but slightly confusing.
Thanks in advance!

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Old 05-05-2017, 08:29 AM   #2
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1973 21' Globetrotter
Houston , Texas
Join Date: Sep 2009
Posts: 2,563
Try doing a google search from outside the forums using search terms like "airforums shell on floor replacement"--I just tried this and got half a dozen hits.

So my thoughts are that doing a floor replacement with the shell on is the hard way to do it. The things that make it especially difficult is wedging the plywood under the wall with the shell not fastened to the frame. You run the risk of knocking the edge of the shell off the outriggers, and if the whole thing comes off, this could be disastrous. Many people who do a shell-on floor replacement split the sheets of plywood down the middle and then scab them back together once both pieces are in place.

I always recommend building the standard wooden gantries, and lifting the shell. Once the shell is off, the gantries can be used to flip the frame during all the frame repair and painting. The under floor insulation, bellypan, new axles, and any retrofit tanks can be installed with the frame upside down, then flip it back over and set the shell back in position. Later, you can use the gantry frames as the basis for scaffolding while you replace an air conditioner, or reseal roof penetrations.

good luck!

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Old 05-05-2017, 09:21 AM   #3
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1973 23' Safari
1970 27' Overlander
Boerne , Texas
Join Date: Jun 2015
Posts: 185
I did a shell on subfloor replacement. I admit, the best way to do this is shell off - but I did not have any help but had time. I was able to do it without getting the plywood in sections by getting a lot of tips on this site. One can clamp on some "extenders" to the outriggers to keep the shell from falling off as you wedge the plywood into the C-channel. For the back piece of subfloor, I did jack up the shell a couple inches and slide in the piece from the rear. There are some description of this in the forums. Straps with ratchets worked well to draw the lower shell back in once the subfloor was in place. All in all, turned out well and was not that bad.
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Old 05-05-2017, 09:57 AM   #4
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1967 26' Overlander
Bugtussle , Oklahoma
Join Date: May 2014
Posts: 220
Here's the method I used: I lifted the shell from the inside by extending a 2x4 across the inside of the trailer about 12 inches above the frame and then fastened the 2x4 to the corresponding right and left ribs with (2) 1/4 inch bolts on each end. Next, I rested a section of 2x6 on the frame below the 2x4 and placed a bottle jack under each end of the 2x4 near the ribs making sure the jacks were firmly supported by the 2x6 on the frame. All I had to do was jack up the bottle jacks a little bit at time on each side and I was easily able to lift the shell a couple of inches allowing me to slide the new plywood into place as a single section from the inside. After finishing a section, I just moved my bottle jack rigging down to the next section. Getting the plywood into place was the hard part. Big hammers, prybars, ratcheting straps, and strong backs are a must. Sorry I don't have any pics handy.
1967 Overlander International 26ft
2006 Porsche Cayenne Turbo S 520hp 530ft-lbs torque 7700lb towing capacity
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Old 05-07-2017, 09:26 AM   #5
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Bend , Oregon
Join Date: Mar 2013
Posts: 5
You Need A Really Good Reason To Do A Shell-on Restoration

I am restoring a 1964 28 foot long streamline empress trailer. Very similar in construction to an airstream of that era.

75% of the plywood subfloor had water damage and needed to be replaced. I decided to leave the Shell on to replace the subfloor. I just finished doing that, and I think I regret it. My primary reason for leaving the Shell on was concern about the gold anodized aluminum trim on the outside of the trailer down at the bottom of the exterior walls. I would've had to drill out many many gold anodized rivets, and I was concerned about being able to get replacement rivets of the same color. Also, I was going to do this part of the work In the midst of a very cold winter, and I thought it expedient to work inside the warmth of a heated trailer.

I ended up getting all the floor replaced and I am happy with the outcome however Ended up spending many many hours on my hands and knees, getting up and down and that in itself was exhausting. Also there were many hours of frustration removing the floor in tight spaces, I definitely should have removed the cabinets, which I stubbornly left installed out of fear of disturbing their fit and alignment on re-installation.

I think you can expect to find Rust on parts of the frame, and by removing The shell and all of the subfloor it will be much easier to identify and remediate the rust damage. I recommend you purchase or fabricate a gray water tank system and embed it within the frame. Having the frame completely opened that job will be much easier.

If I were to do it all over again I think I would figure out a way to get some new gold anodized rivets and do a shell off restoration.
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Old 05-10-2017, 09:02 AM   #6
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1964 26' Overlander
1974 31' Sovereign
Milton , ON
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Either way will work

Floor replacement can be done shell-on or shell-off, and each has their plusses and minuses. We did it shell on. If I had had a big enough indoor space I would have removed the shell.

I started at the rear and as I removed sections of floor I left small pieces where the shell was connected to the frame. I had to do a lot of welding, which would have been easier with the shell off. I didn't find it a problem to get the new plywood into the C-channel. The first section (rear most) I cut in half, but after seeing how easily the rest of the floor went in I think I could have installed it in one piece.

Here's a photo as I was getting started. After replacing the floor I decided to removed all interior skins to re-insulate and rewire. If I'd known from the beginning I was going to do that I would have removed the interior skins before replacing the floor.

Grant Davidson
Milton, ON

1946 Spartan Manor
1954 Va-Ka-Shun-Ette
1964 Overlander
1965 Avion C-10 Truck Camper (
1974 Sovereign
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Old 05-11-2017, 08:27 AM   #7
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1986 25' Sovereign
2008 F350, 6.4L diesel , Oak Harbor, WA
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It has likely been pointed out:
Shell on works well for specific areas, such as a rear bathroom floor. Most trailer only have small areas that need to be fixed.

If you want to replace the interior including the skins then shell off is the way to go.

The trick is to know how far you want to go,
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Old 05-11-2017, 08:38 AM   #8
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1972 31' Sovereign
Lexington , Minnesota
Join Date: Feb 2009
Posts: 3,548
We did shell on floor replacement. It's in our thread "Little Girl Refurb" in the '70's section. It took us a weekend and 2 of us to do a 31 ft trailer. Shell off would have been easier in hind sight, but we're NOT going to re-do it now!
It's do-able.

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Old 05-11-2017, 10:30 AM   #9
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1967 17' Caravel
Cadillac , Michigan
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I did a shell on because of mostly working alone.
There is a lot of crawling around, banged up shins and numerous scrapes.
But I survived and the trailer is now nearing completion.
If I had help I'd have done a shell off.
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Old 05-11-2017, 12:57 PM   #10
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1971 21' Globetrotter
Arvada , Colorado
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I did mine shell on also. Only problem I had was the front sheet at the "C" channel due to the hidden fasteners. It was easily overcome with a Saws All.

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