Repairing sub-sub floor

[FlyingChops]

So, I'm well down the path of replacing all of the flooring in our coach. What appeared to be a leak that effected about 6 tiles worth of flooring is actually 3 different leaks with extensive water damage.

I've removed a substantial amount of the front half of the coach's sub-floor, insulation and what I'm calling the "sub-sub floor".

I'm hoping that someone has done a similar repair and has some tips.

Underneath the tile/carpet is the sub-floor, which sits on top of a 1.5" x 1.5" aluminum frame which is filled with insulation. Under the insulation and the frame there is another layer of plywood. That plywood that is underneath where the insulation goes, is sandwiched between the aluminum floor frame and another aluminum "shelf" underneath that supports it.

How do I go about replacing that lower layer of plywood once I get the old piece out? The old layer in a couple of areas is completely saturated with water, it pulls out like wet dirt.

Can I get any better access from underneath?
Do I work a piece the width of the framing member underneath and then just rest my new piece on the lower "shelf"?

Anyone done this before?

Any thoughts/help/tips/etc. appreciated!

[Ernie Ekberg]

I do flooring for a living. Your situation is pretty unique. I'd like to help, but I need to see some photos, please.

[Algoma]

That piece of plywood (OSB) below the insulation actually sits on the chassis and outriggers. The aluminum frame bolts through this layer to the chassis. The lower sheathing is covered in a waterproof material and unfortunately this traps any moisture that gets in to the wood and it does not dry out and rots. If it is not completely rotted out you could try drying it out and then using an epoxy wood hardener to saturate the wood and firm it up. I did this on a small area close to our lift door and it worked well.

[FlyingChops]

Originally Posted by Ernie Ekberg

I do flooring for a living. Your situation is pretty unique. I'd like to help, but I need to see some photos, please.

I'll post a few this afternoon, I've been taking them along the way.

Algoma:

I'd LOVE to be able to take your suggestion everywhere - and I will for a couple of the smaller areas where it isn't feasible to get to that lower layer (near the sides, at the corner of one of our slides) but I'm talking about an area the size of 2 sheets of plywood that I need to replace. They were saturated with moisture, I've already removed a ton of what was the equivalent of wet sawdust.

I have a quart of wood hardener here that I plan to use at the edges, everywhere I remove material.

Thanks for the help, guys!

[FlyingChops]

Originally Posted by FlyingChops

I'll post a few this afternoon, I've been taking them along the way.

Okay, a few pictures of my first coach "mod" :-)...

This one is what it looked like after I removed the top layer of subfloor and the insulation:


These next three are after I removed the bottom layer. You can see the black plastic that is under the bottom layer. If you go into the basement storage and look up, you see the underside of this black plastic.





Because there is essentially an aluminum ridge/shelf along the bottom of the aluminum frame, at least where it is running the length of the coach, my plan is to put new plywood on that shelf, filling in the gaps that are left after what I've removed. I'll coat everything that is exposed with wood hardener first, install the plywood, install new insulation and then install the new subfloor.

If you guys have any suggestions on how better to do this, please share!

A couple of more pedestrian questions while I'm at it...

1) I noticed that the existing subfloor isn't screwed down at all, just copious amounts of glue. Should I just glue as well? Screw/glue as if it was a house? What kind of glue should I use?

2) Any reason NOT to toss a 1/4" layer of luan/birch plywood on top of this whole thing once I'm done/before I install my new glue-down wood floor? It appears that I'll have plenty of clearance for the slides (there is 1 1/8" above the subfloor, my flooring is only 3/8" thick) and I think I'll get a flatter floor taking into consideration the OSB chips that I've sanded down, the areas I'll fill, the repairs I'm talking about above.

Thanks for the help - it's always nice to add a hobby - I can tell this one is going to be fun (this is our first coach, had it <60 days).

[Algoma]

This is the area where I had some water damage, but only the top OSB layer.
After gluing down the new piece I then added a second sheet of 1/2" plywood across the whole kitchen area to take the weight of the lift and screwed this to the OSB. So you shouldn't have any problems if you want to add some luan sheeting.
You have to glue the OSB to the insulation but you can put some sheet metal screws in to the framing although it is very thin. I think I used "Power Grab", but it was some while ago.
On the older coaches like mine the extrusion that the bay doors hangs from is screwed directly in to the side of the lower wood sheet. If yours has rotted out there may be nothing holding that extrusion on.

[Ernie Ekberg]

under the black plastic, is there any metal joists? If so- you will be good to go with your reconstruction. I would use the Styrofoam boards for your insulation. Screw the top floor down on the aluminum then you can add your wood floor on top of that. If you sue urethane adhesive, your new floor and old will be solid.

[EngineerMike]

You should be able to piece the lower osb back in working the pieces in under the tube so then screwing them in up to the aluminum tube thru the plastic sheet using some sort of strip, say aluminum.
Then you can bind the osb pieces together with 1/4" hobby plywood & structural glue on top of the osb.
Then place 1.5" foam routed for relief where the hobby plywood socks up. Then glue & screw down top osb patches.