A better plywood floor

Darkspeed · September 21, 2015, 10:27:21 AM

So I have been doing a lot of research and getting scraps and testing them and have settled on AdvanTech waterproof plywood. Anyone use it before?

Locally it is $22 for 3/4 T&G sheet which is cheap!

My plan is to use 3/4 on the bottom then a couple inches of closed cell foam board then a 1/2 on top. > http://www.rmax.com/products/wall-products/thermasheath-3/#tabs-2

Any advice from anyone who has done a plywood foam sandwich floor?

https://www.youtube.com/playlist?list=PLD4DABC7254437F2D

something like this > http://winterfarmbus.blogspot.com/2011/01/insulation-and-sub-floor.html

TomC · September 21, 2015, 10:59:52 AM

I lucked out, my transit has 1" plywood with 1/4" rubber mat bonded to it. No additional insulation. Plywood in itself insulates well. I would stay away from a sandwich floor. If you want insulation, spray foam from underneath. Good Luck, TomC

chessie4905 · September 21, 2015, 11:01:43 AM

http://www.bobvila.com/articles/526-enhanced-plywood-and-subfloor-products/#.VgBKpsrD8v4

Iceni John · September 21, 2015, 11:52:30 AM

I second Tom on this. There shouldn't be any need for additional insulation if you have an inch or more of good plywood, unless you live somewhere really really cold. However, good is the operative word here - crap plywood probably won't hold up or will be so knotty as to be worthless. FYI, I have 3/4" of marine ply, a layer of what looks like tar or bitumen, another 3/4" of marine ply, and 1/8" Armstrong rubber flooring, and it insulates just fine. You'll also lose headroom with unnecessary floor thickness.

John

Scott & Heather · September 21, 2015, 11:55:40 AM

Plytanium here. Waterproof coating on the luggage bay side and we coated thick with poly on floor side

Sent from my iPhone using Tapatalk

Darkspeed · September 21, 2015, 12:14:34 PM

Well part of the reason I dropped the floor in my 4106 8" is to allow more room for serious insulation ( as well as I like the feeling of the taller ceiling and I have tall relatives)

The two rear bays will be insulated the rest will be uninsulated. I have allowed for 3" of closed cell E85 icynene spray foam ceiling , walls, which will give me around R19.5

Plywood only has 0.95 R per inch on a good day so it could be a big loss of heat/cool without something isolating it especially conducting to the metal floor supports.

luvrbus · September 21, 2015, 12:41:05 PM

I sandwiched 1 inch blue board between 2- 5/8 pieces of plywood it made a lot warmer floor in Wy and Idaho,I was told it had a R value of around 9 the floors can get pretty damn cold in a bus.

The next bus had a Nuheat floor heating system I loved that gadget

Darkspeed · September 21, 2015, 12:42:55 PM

Quote from: luvrbus on September 21, 2015, 12:41:05 PM
I sandwiched 1 inch blue board between 2- 5/8 pieces of plywood it made a lot warmer floor in Wy and Idaho,I was told it had a R value of around 9 the floors can get pretty damn cold in a bus.

The next bus had a Nuheat floor heating system I loved that gadget

+++Clifford, That is what i was hoping to hear. I should be at 14 R with my current plan.

Jeremy · September 21, 2015, 03:17:10 PM

The stuff shown in those photos isn't plywood - OSB is cheap and has it's uses but I'd never use it as an alternative to proper plywood for a floor myself, except perhaps if I was just sheeting-out a domestic loft or something

Jeremy

chessie4905 · September 21, 2015, 03:24:34 PM

I would only use marine plywood.That stuff is basically flake board and moisture "resistant". Don't cheap out now with all the work you're doing. Plywood retains fasteners better also. jmo

luvrbus · September 21, 2015, 03:34:21 PM

If you sandwich I was told you need the screws long enough to go through both pieces of plywood and the foam to what ever you were attaching to that is what I did I had no squeaks and was rock solid

belfert · September 21, 2015, 03:51:10 PM

I like AdvanTech. I want some for a project, but I can't find anyone locally who seems to carry it. I would compare weight between AdvanTech and plywood subfloor. Plywood might be lighter.

You seem like you are totally re-engineering and rebuilding your bus. I hope you don't end up spending 10 years on it and never get it done like some.

Darkspeed · September 21, 2015, 04:07:22 PM

Quote from: belfert on September 21, 2015, 03:51:10 PM
I like AdvanTech. I want some for a project, but I can't find anyone locally who seems to carry it. I would compare weight between AdvanTech and plywood subfloor. Plywood might be lighter.

You seem like you are totally re-engineering and rebuilding your bus. I hope you don't end up spending 10 years on it and never get it done like some.

These guys have it in your area> http://www.shawstewartlumberco.com/about-shaw-stewart

Regular plywood absorbs water and supports mold, no way I would use it as a floor with out several coats of sealer = too much work

Im doing my best to finish it, I am in the process of ebaying my previous lifestyle to buy materials to build the bus.

Jeremy · September 21, 2015, 04:53:19 PM

If by 'regular plywood' you mean cheap interior grade stuff then yes it does, but that's obviously not what you'd use for a floor. I don't know about the American market but here 'flooring and roofing' grade plywood is widely and commonly available and would be much better (stiffer, stronger and more durable for a given thickness) than OSB. The reason that OSB is cheap is that it's basically bits of scrap wood squashed together with glue - but lots of joins and no long fibres mean poor structural properties

Not to labour the point, but if cheap OSB was satisfactory for a bus floor then the manufacturer would fit them as standard. But they don't, they use plywood

Jeremy

Darkspeed · September 21, 2015, 05:16:19 PM

The AdvanTech is more like plywood than OSB and from what i have seen it is stiffer than plywood. I refuse to use regular OSB for anything. The AdvanTech also is formaldehyde free which i think is important for indoor use. https://www.youtube.com/watch?v=ceFc-02r9J8