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Post by wisconsinjoe on Mar 13, 2016 11:32:38 GMT -8
I'm getting ready to start my scratch build project and wondering about the best kind of plywood to use for the floor. Planning on 3/4 inch material, something tongue and groove. I will not be using floor joists or any flooring insulation, just attaching the plywood to the steel framing. Should I be using special marine grade or will AC or BC do the trick? Also, what can I use to paint on the underside of the plywood? How should the edges and butt joints be treated to protect from water caused rot? The original floor had some kind of black painted coating. Although the camper had been thoroughly ruined and rain soaked for years, the only really rotten parts of the floor were where they were covered underside with aluminum flashing.
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ladywendolyn
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Post by ladywendolyn on Mar 13, 2016 13:42:28 GMT -8
Interesting that it only rotted where covered. The temptation is to cover things but it seems to trap moisture.
One of the experts will chime in on best plywood..
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Lola53
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Post by Lola53 on Mar 13, 2016 22:28:11 GMT -8
Interesting that it only rotted where covered. The temptation is to cover things but it seems to trap moisture. One of the experts will chime in on best plywood.. I bet $0.02 that the wise ones will advise Not to use Chinese plywood -"I don't know what they use for glue, but it's not glue." :-) |
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Post by danrhodes on Mar 14, 2016 6:33:35 GMT -8
My only wisdom is gained from failure. I bought the Chinese interior grade sanded plywood that's often prominently displayed at the front of the lumber area at Home Depot. I had it all cut, undercoated and ready to install when a few folks here told me that was a dumb idea. I did some soak tests and it seemed OK, but when I tapped the test board on the floor, it just fell apart and could be torn apart with my bare hands. I replaced it all with exterior grade plywood from a local lumberyard and haven't looked back.  |
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Lola53
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Post by Lola53 on Mar 14, 2016 16:35:02 GMT -8
I'm a believer. No Chinese plywood for Lola. Not only the issue of falling apart, but they seem to be dumping hazardous waste into any product they can (drywall is an example).
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Post by vikx on Mar 14, 2016 20:01:10 GMT -8
I use a black coating product called Damp Proofer. It is water clean up and takes a while to dry but does add some protection.  |
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Post by wisconsinjoe on Mar 15, 2016 11:32:17 GMT -8
Thanks Vikx. What kind of plywood do you use for the floor? I'm considering a 3/4 inch T&G Sturdifoor plywood. The original was 5/8. Marine grade seems excessive and expensive. Don't want to use CDX.
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Post by vikx on Mar 15, 2016 20:54:04 GMT -8
On the trailer above, I used 1/8 masonite coated underneath for the belly. After insulation, regular grade 1/2 plywood bolted thru the joists and frame, along with field screws. Top subfloor is better quality 3/16 luan sheets, air stapled. Perfect for vinyl flooring.
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chriss
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Post by chriss on Mar 18, 2016 17:58:02 GMT -8
There's also MDO and HDO plywood. It's supposed to have similar qualities to marine plywood. It's the same material used for signage and concrete firm boards. I haven't heard of anybody using it in vintage trailers, but we have a utility trailer with an MDO floor and it's holding up well to the weather and use.
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edbrown
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Post by edbrown on Mar 20, 2016 7:05:47 GMT -8
There's also MDO and HDO plywood. It's supposed to have similar qualities to marine plywood. It's the same material used for signage and concrete firm boards. I haven't heard of anybody using it in vintage trailers, but we have a utility trailer with an MDO floor and it's holding up well to the weather and use. There are three things special about Marine plywood: No voids and fewer defects, absolutely waterproof glueline, and thinner veneers. The last is so defects reduce the strength less. Of those three advantages, MDO and HDO have the waterproof glue line. The advantage of MDO and HDO is that one surface is really smooth and takes paint well. Important if you're going to paint the floor and walk on it. Not a big advantage otherwise. I'm not an expert, but I just got a good quality AC Exterior plywood from a lumber yard I trust. It had this on it.  which I think is good. On the other hand I'm going to have an insulation space and another layer below it. That layer will be similar quality but well with an epoxy layer on the bottom. If I were going to have a single plywood layer without protection I'd go with a Lloyd's approved marine ply. That's what I used when rebuilding an old fiberglass boat. Meranti plywood. Heavy, pricey, and very strong. |
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Post by wisconsinjoe on Dec 30, 2019 15:50:46 GMT -8
There's also MDO and HDO plywood. It's supposed to have similar qualities to marine plywood. It's the same material used for signage and concrete firm boards. I haven't heard of anybody using it in vintage trailers, but we have a utility trailer with an MDO floor and it's holding up well to the weather and use. Is the MDO surface exposed to weather, on the bottom, roadside surface? If so, is it coated with anything? |
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Post by vikx on Dec 30, 2019 21:24:03 GMT -8
I'm not a ply expert, Joe, but the coating has changed to Black Beauty fence paint sold at Tractor Supply. Same goopy stuff, water clean up. Home Depot quit carrying the damp proofer product.
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roadtripper
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Post by roadtripper on Jan 1, 2020 7:13:04 GMT -8
Back in my younger concrete days we used mdo for formwork on walls often. With the smooth surface it could be oiled after use an re used many times leaving a smooth concrete wall surface and was easy to strip. I don’t see any real advantage to using it on your floor. My opinion is use quality plywood and coat the bottom and all the cut edges before assembly. That black stuff from tractor supply is good and inexpensive. I used a floor paint made for exterior floors on the bottom of mine. But maybe mdo coated would be extra nice and worth the few extra bucks.
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