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Old 10-30-2006, 06:48 AM   #1
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Tore up floor - How do I seal the metal ? (Holes, etc)

I started to tear up the floor and found soggy 3/4 plywood and a lot of small screws rotted away that I had to drive down thru the floor. I now have rust that needs to be stoped. The real question is what to put down over that to fill all the holes. I'm thinking some kind of thin sealant (roofing tar maybee) then roll out tar paper over it. This would give me a clean surface to lay my new wood down on. Next question, how have you guys be attaching your plywood to the floor ? From top down with screws ? or bottom up with screws? Any other ideas. Thanks[/b]

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Old 11-01-2006, 02:56 PM   #2
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We used small squares of sheet metal, glued in place with silicone. First, we sanded any rusty areas, swept/vacuumed, wiped w/mineral spirits, and painted the whole floor with rust-inhibiting paint...then patched the holes.

We screwed the plywood to the steel floor, after pre-drilling and countersinking the holes. Between the metal floor and the plywood is 1/2" rigid foam insulation and a 6-mil vapor barrier. If you plan to be in cold weather, and can afford to lose some headroom, I recommend insulating the floor as much as possible. Ours gets quite chilly.

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Old 11-01-2006, 05:20 PM   #3
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Sean, the little metal squares sounds good, I'll cut some and see how it works.


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Old 11-01-2006, 09:47 PM   #4
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My holes are all just sealed with an outdoor rated Liquid Nails. Yeah, it's booty fab, but it was quick and easy. After that, all the rust was sanded off, the floor was swept, and hosed out with TSP. We then painted it with two THICK coats of an outdoor metal primer that is absolutely fantastic. To secure the furring strips, we put a good thick bead of Liquid Nails on them, held them in place, predrill, and screwed them in with 10 year stainless screws. The screws were really just to hold it down until the liquid nails dried. The idea behind using the adhesive was that it would prevent squeaks.
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Old 11-02-2006, 08:22 AM   #5
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For dealing with the rust, I recommend a product called Ospho, it'a a rust converter you brush onto rusted (but CLEAN) steel.
Then paint it.

For sealing the holes, I think the best way is galvy sheet metal, secured/sealed in place with butyl caulk. Silicone caulks contain acid, used in the curing process, and it may attack the metal long-term.
Then place a vapor barrier over the sheet metal (heavy poly sheet works well), and then your underlayment/finish flooring.

The poly sheeting acts as a vapor barrier, reducing/eliminating moisture from migrating to the floor from the interior of the bus, causing rust.
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Old 11-02-2006, 08:40 AM   #6
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I used the exterior quality liquid nails caulk stuff and then layered over it with 30# roofing paper. Followed by 1" pink foam board and 3/4" tongue and groove plywood. Just put my heater in the bus last night, 33* outside and it was 75* inside the bus.

I also have 3.5" of insulation on the walls with 3/8" beadboard and whatever the bus came with in the ceiling.
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Old 04-07-2020, 04:36 PM   #7
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Roofing tacs over floor holes

I used galvanized roofing tacs to fill the floor as they are only half inch long nails but have a flat wide head. Fit perfectly over most of the holes. I dipped the heads in a bit of jb weld and went back later and patched with liquid rubber once they set. Absolute overkill i'm sure, but my floor hasn't leaked once!
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Old 04-10-2020, 11:43 AM   #8
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I was lucky in that my floor is aluminum, but unlucky in that I ripped huge holes in it for the same reason. I opted to use fiberglass/epoxy to cover most of the holes. I put a single coat of metal primer on, then 1" of rigid insulation, then 3/4" plywood. I through-bolted this plywood to the floor, putting the washer/locking washer/nut underneath.
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Old 05-15-2020, 02:07 PM   #9
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What about Ice and water shield stick down rook membrane?
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Old 05-15-2020, 06:05 PM   #10
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We did something uncommon here, but it turned out pretty well. We used KBS rust seal (moisture-cured 1K urethane) to paint/coat the floor. In the process, we used fiberglass mesh patches over all the bolt holes, using the paint itself as you would a fiberglass resin. Once cured these patches are hard as a rock. You could literally set screws in them if you wanted to (though I wouldn't test them with much force). For the intended purpose - sealing what will become a subfloor - it worked great. The only downside is that you need at least 3-4 coats over the patches themselves, and sometimes even then you find pinholes in ones that looked solid during application. On these we just resealed w/ a 2-component epoxy. See here for more:

FYI: Since that post we've been working in the bus for weeks, dropping tools, dripping solvents, scraping ladders... & the kbs rust seal remains bulletproof.
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Old 05-15-2020, 07:18 PM   #11
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