Help Please. Perimeter C-channel bolts and sub-flooring questions?

[Re-Pete]

In doing a total sub-floor replacement does removing all of the perimeter bolts essentially disconnect the shell from the frame? If so, should I only do sections or sides at a time? What are the do's and don'ts to follow.




Also, since what I'm replacing is essentially one solid sheet of OSB and I'll be using 4' x 8' material, what is the best type of sub-flooring material and what's the best way to prep and install it, regarding direction, staggering, etc.?
Thanks

[Coloradobus]

Don’t use OSB. Use marine grade or out door rated. Don’t put flooring seam at entry door, this eliminates high traffic flex when two wood pieces meet at entry door.

[68 TWind]

I would seal all the edges with several coats of a good poly spar varnish or better (which is what I did) use West System epoxy (or any good brand) and put a couple of coats along the edges and top and bottom about 6 inch band. The edges are where most of the water damage is, especially in the rear. I would not use OSB. I would install the new floor in the same pattern as the original in regard to stagger and layout.

[Re-Pete]

I definitely agree. NO OSB! OSB is a terrible idea for sub-flooring. My current sub-floor is OSB and it's flaking, plus I believe the rot is even worse as a result of the OSB's composition. As far as re-installation... the old floor was practically one massive sheet. I'm guessing originally at least 22' x 8' as there is only one seam that runs crosswise just 3' back from the front curve. From there it's one solid sheet all the way to the rear bulkhead. I've never seen sheets this big. Anyway, now that I've pulled up 75% of the floor I see that 4' x 8' sheets of material laid crosswise are going to work out great with very little waste, totally supported with cross beams on the long edges and the frame in the middle and at each end. I also agree that it must be a water rated plywood or one of the newer closed cell materials made for boats. The synthetic material is VERY expensive, but most of it is half the weight of plywood which reduces weight and allows for something else to weigh more. Gonna take some thinking.

Anyone care to comment on my perimeter bolt question?

[Belegedhel]

For your perimeter bolt question, yes, if you remove all the bolts that connect the C-channel to the wood, and all of the bolts that connect the ends of the outriggers to the C-channel through the subfloor, then yes, you have almost completely disconnected the upper shell from the frame. The exception would be if your model of trailer has metal plates buck-riveted from the shell directly to the frame in the front and back. At any rate, It probably isn't necessary to do it in sections (in fact the clamping force from the unreleased sections will make it all harder to do). That being said, if you live in an area that experiences high winds or tornadoes, you will want to fasten down the shell so that it doesn't catch a good side-wind and take off (and definitely don't tow it anywhere with the shell released).

As to materials, it is easy to over-think it. Many-many-many trailers were built using plain old plywood, and lasted for 40 years before there was significant rot. Had that plywood been treated with even the most basic polyurethane around the perimeter and at the edges, the wood would have outlasted the frame (which is also usually in need of significant repair after rusting away for 40 years). So for a good combination of utility, cost and quality, I would recommend a cabinet grade of plywood (ie., think a minimum of surface voids), treated with 2-3 coats of plain-jane polyurethane on and near the edges. Marine grade is way overkill--not really any more liquid resistant despite the name. The engineered materials are all fine and well, but they will likely outlast the frame, so what's the point.

good luck!

[skyguyscott]

Since you asked, the consensus here on the best subfloor material seems to be a product called Coosa Board.

This remarkable composite material is virtually waterproof, an important consideration since among the most common and costly repairs necessary in an Airstream is the floor due to water damage/rot. And it is important to remember that no mater how leakproof you think your airstream is, water will eventually, inevitably get to your floor somehow, someway, someday -- weither through leaks, condensation, spills, plumbing failures, open windows, cracked seals, rear bumper storage area etc. The main problem areas seem to be around the door, the front and rear sections, around the shower, toilet, and wheel wells, and so on.

And so, since you are aready this deep into it, and likely don't ever want to have to do this again, either in whole part or in sections, some of us spend the extra $$ to do Coosa Board, which is:

• virtually water proof
• insect and critter resistant
• mold and mildew resistant
• just as strong as plywood of the same thickness
• just as easy to work with as plywood
• Actually 30% lighter than plywood (!!!)

The main downside? It's more expensive that plywood. But you'll have to weigh that cost against the value of knowing you will never have to worry about the floor again EVER for the life of your trailer, nor will the next owner nor the next. It will remain solid and strong, never mushy, even after the leaks/spills/wetness etc.

[toastie]

Re-Pete

Don't waste your money on marine grade plywood, you're not building a boat. Go with 3/4" AC plywood and apply a good sealer. I would also recommend no insulation under the floor. If you're doing a shell off make sure you brace the shell before lift-off. Should be good to go for many years.

toastie

[Re-Pete]

Thanks everyone for you input and counsel.

Belegedhel, Thanks for the help on my perimeter bolt question. Smart and helpful.

Everyone's flooring advice was also Smart very Helpful. I enjoyed reading everyone's different point of view. My main take away on the flooring is make sure it can withstand repeated run ins with moisture, especially in the spots mentioned, because, as I am already painfully aware, it will get WET.
I'll do my best to post a followup when I make my final decision.

Best wishes,
Pete

[toastie]

I would do a shell off restoration, por 15 the frame.....much easier.

https://www.por15.com/Rust-Preventive-Coating_c_11.html

toastie

[Dingo Girl]

As you remove the old floor from the edges save some scraps of the old floor & clamp the pieces between the C channel & outriggers. This will keep the shell from bowing out.

[Re-Pete]

Originally Posted by toastie

I would do a shell off restoration, por 15 the frame.....much easier.

https://www.por15.com/Rust-Preventive-Coating_c_11.html
toastie

Thanks toastie, Not sure yet on the shell off, but the Por 15 is already part of the plan.

Originally Posted by Dingo Girl

As you remove the old floor from the edges save some scraps of the old floor & clamp the pieces between the C channel & outriggers. This will keep the shell from bowing out.

Thank You Dingo Girl, I'm not sure I'm following you. Sorry I'm a bit slow here. Would you mind providing more explanation. Someone else suggested that I leave small blocks of the floor inside the C-channel spaced out around the the perimeter to prevent the weight of the shell from crushing the channel while the frame restoration is in progress. They also restored their frame with the shell on. I'm still on the fence on doing a shell off. It's kind of tight in my back yard.

[Dingo Girl]

I'll get some pictures together of how I did it and post them soon.

[Dingo Girl]

Sorry the pic is not so clear.
You can see the clamp (I prefer Kant-Twist clamps) the C-Channel and the outrigger.
I took the all floor all the way out and clamped as I went along.

[Re-Pete]

Originally Posted by Dingo Girl

Sorry the pic is not so clear.
You can see the clamp (I prefer Kant-Twist clamps) the C-Channel and the outrigger.
I took the all floor all the way out and clamped as I went along.Attachment 317666

Thanks for this. What I believe I'm seeing is the C-channel is clamped from the inside to the outrigger. Doing this would maintain the proper relationship of the shell to the frame. This is a very helpful tip. Thank you very much.

Is the small section of the old floor used as a filler for the channel, to prevent the clamp from crushing it?

Pete

[Dingo Girl]

Yes. It holds the shell in place as you remove the old floor.
1.Outrigger
2.Piece of old floor
3.C channel
The clamp holds it all together .

When you put the new floor in do the ends sections first, then the middle.
It worked out great for me.
I learned this from Aerowood an extremely knowledgeable forum member.

[Re-Pete]

Originally Posted by Dingo Girl

Yes. It holds the shell in place as you remove the old floor.
1.Outrigger
2.Piece of old floor
3.C channel
The clamp holds it all together .

When you put the new floor in do the ends sections first, then the middle.
It worked out great for me.
I learned this from Aerowood an extremely knowledgeable forum member.

Dingo Girl, Thank you I appreciate all of your help. The help I'm receiving from you and others will certainly help me avoid some potentially punishing mistakes. It's really great how we all get to give and receive on this forum, lots of good karma.

[Dingo Girl]

Best forum out there.