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Discussion Starter #1
I'm hoping to install my floor tomorrow (159 regular). My plan with questions:

1. Cut a template from builders paper, leaving a 1/4 inch gap along each wall. How do I make the template out of builders paper? I'm assuming I just cut and tape pieces together-is there a way to press it into the edges instead to directly copy a line? Apologies if this seems trivial/silly.

2. Cut 1/2" poly and 3/4" hardwood ply to the size of the template, polyurethane ply

3. Countersink bolts using existing holes and adding 4-5 new bolts. The D ring bolts are self tightening. Should I just use these same bolts but longer ones or should I use true washer/nut hex bolts? What about for the others-members often talk about bolting through the floor. I assume this is literally just right through the van body without a rivnut/fitting and then securing a hex or lag with a nut from below?

4. Use foam dowel on the two sides to close the gap/prevent squeaks. Should I be using any glue anywhere?
 

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I just lay heavy paper called rosin paper on the floor and cut the edges with a mat knife/scissors. I cut a few V shaped cuts randomly in the paper sheet and fold the paper back and use tape to hold it down. Then overlap another sheet of paper and do the same and tape it to the first one and then the next till done. When the pattern is all done I roll it up from one end removing the taped down places and transfer it to the polyiso sheets and cut the perimeter and then test them laid un loosely. If all is well I cut the plywood with the same pattern and lay it in loosely on top and drill the hold down holes. I used 1/2 inch polyiso and 1/2 inch hardwood plywood and am happy with the results. I did then cut out the shapes of the bases of my cabinets so the cabinets extend to the metal floor and are surrounded by the plywood floor. That way the cabinets cannot slide. I used the D rings to hold cabinets so some were replaced with longer bolts some were replaced by fender washers and bolts. No Glue Needed!
IIRC I used a hole saw to cut the holes for the D ring bases but I am old enough I CRS.
 

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MMXVI - L2H2 in IN
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1. I took 3 x 1/2" polyiso 4x8 sheets cut to the width of the floor and scribbled the front indent and wheel wells, didn't sweat the nooks and crannies, I filled those with can spray foam.

2. Used the polyiso as templates for the plywood, didn't worry about the nooks and crannies left by the plywood. I used 1 small mending plate between 2 sheets that didn't level up, because I didn't use biscuits, dowels or a scarf to joint the sheets. I used left over house paint on all sides.

3. I countersunk and used pan head bolt 50mm long to the plywood down.

4. I used gaps and crack foam to fill imperfection around the edge. The edges of the plywood will have stuff covering them up anyway. I used no glue. I don't have squeaks.

I spent more time staring at the project than working on it.
 

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2014, 138WB, High Roof, Gas, SW MT
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Hi,
I did not use a paper template, and it seems like the shapes are simple enough that you really don't need one. This photo shows how I fitted the polyiso sheets:




I glued the polyiso to the floor with Great Stuff and the plywood to the polyiso with Great Stuff. Minimal use of fasteners to hold it down.

The approach I took was that the things like the galley cabinet and the two bed pedestal cabinets (which had all the heavy stuff in them) needed to be anchored through the van floor with large through bolts that go through the floor and with reinforcing plates under the floor to keep the bolts from pulling through. The idea being that in case of a crash you won't have hundred lb items (like batteries and water tanks) joining you in the cab at 50 mph.


This is a view from under the floor (looking up at the bottom of the floor).

If you use this philosophy, then its not so important how well the floor is attached to the van -- what matters is how well the larger items are anchored through the van metal floor with bolts.
In my case, the Great Stuff does a great job of holding the floor together with no shifting or squeaks.

More details here: http://www.buildagreenrv.com/our-conversion/our-conversion-flooring/
One thing I'd say in hindsight is that the 1/4 inch strips to fill in the corrugations in the floor are probably not necessary.

I guess I'd just say that from a safety point of view you really want to emphasize anchoring the big items well enough to protect you in a crash.

Gary
 

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I'm about three weeks or more behind kifo4713, and have similar questions.

How important is the quality of the plywood? When you look at the reviews on HD and Lowes, you get the impression that most hardware store plywood is of poor quality with voids and such. For me this is effectively underlayment. Can I get by with "whitewood" or poplar rather than birch and save the good stuff for the cabinets?

RD, doesn't your approach of locking in your cabinets mean that the floor beneath them isn't insulated? If so, are there any downsides to this?
 

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MMXVI - L2H2 in IN
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I used $16 1/2" sanded one side plywood. I had 1 spot where I had to put a mending plate (3/4" x 4") between 2 sheets. My logic is once I start putting stuff around the perimeter it will all level out. I'm glad I didn't buy $40 plywood since since I screwed up 1 cut. I covered the plywood with eva interlocking foam tiles, I'm not sure why I would use expensive plywood for the floor.
 

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I'm about three weeks or more behind kifo4713, and have similar questions.
How important is the quality of the plywood? When you look at the reviews on HD and Lowes, you get the impression that most hardware store plywood is of poor quality with voids and such. For me this is effectively underlayment. Can I get by with "whitewood" or poplar rather than birch and save the good stuff for the cabinets?
RD, doesn't your approach of locking in your cabinets mean that the floor beneath them isn't insulated? If so, are there any downsides to this?
Go look at the plywood. You want sheets that lay flat and stay that way. For me that meant hardwood plywood and birch was a few dollars more than popular and had a much harder veneer surface. YMMV but this is not an area to cheap out on. H-D and Lowes have poorer ply than most lumber yards we used building homes. They should not be saying anything.
Most of my cabinets have the polyiso dropped inside the bottoms under the drawers etc. so they are insulated.
 

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Discussion Starter #8
Today I almost bought some nice 3/4" hardwood birch ply and I noticed it's 70 lbs/sheet.

That's a ton of weight! The problem with 1/2", I've read, is that if you're countersinking bolts the 3/4" is better. Additionally, securing some (not all) items to the floor is a bit better with 3/4".

Curious to see what everyone thinks about the floor weight. I'm assuming a solid, strong floor is very important, and thus perhaps it is okay to splurge in weight here.
 

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The weight is not an issue. I used 1/2 but my cabinets extend down through the floor so attaching to it wasn’t a big deal. 3/4 would be MUCH better to hold screws or bolts.
 

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Curious to see what everyone thinks about the floor weight. I'm assuming a solid, strong floor is very important, and thus perhaps it is okay to splurge in weight here.
We agree with RD that you're obsessing too much over the weight. However, having said that, we went with 1/2" birch plywood . . . not because of the weight, but because, at 6'4", we wanted to minimize the thickness of the floor and ceiling. Our plywood, which lays on a 1/2" polyiso sub-floor (with no insulation between the floor ribs) seems quite solid.
 

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Would I be wrong in assuming if you have the OEM Mat in the back you can remove that to use as a template for floor fitting, I don't actually have my van yet but it is coming with the load space mat.
 

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I'm about three weeks or more behind kifo4713, and have similar questions.

How important is the quality of the plywood? When you look at the reviews on HD and Lowes, you get the impression that most hardware store plywood is of poor quality with voids and such. For me this is effectively underlayment. Can I get by with "whitewood" or poplar rather than birch and save the good stuff for the cabinets?

RD, doesn't your approach of locking in your cabinets mean that the floor beneath them isn't insulated? If so, are there any downsides to this?
Floor plywood is very important. Spend a bit more on the plywood for the floor and use marine plywood. The floor is a real pain in the butt to replace after your build is in if it starts de-laminating from moisture down the road. The issue isn't the wood type it's the glue. Cheap bigbox plywood uses glue that's not at all waterproof. Look for WBP (Water Boil Proof) resin plywood which is completely imperious to water. The bonus is since this type of plywood is generally stronger and has more plys you can use thinner plywood and still have a solid floor.
 

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2014, 138WB, High Roof, Gas, SW MT
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Hi,
If you are looking for a floor that will stand up to difficult conditions (wet or high loads), I'd consider MDO (Medium Density Overlay) plywood. Its a high quality plywood that is laminated with water resistant glue and then overlaid with a resin impregnated fiber face sheet. It is used for things like freeway signs and chemical tanks. In my experience, it is flat when you get it, and stays that way for many years.
Its pretty readily available -- two lumber yards in our town of 30K people stock it.
About $50 a sheet.
http://bluelinxco.com/files/IndustrialDecorativePanels/APA HDO and MDO Plywood.pdf

If you want a bomb proof floor, then HDO (High Density Overlay) plywood, which is a grade tougher than MDO, but probably overkill.

I think that half inch MDO would be fine -- don't think you need 3/4 inch.

Gary
 

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I had a bad experience wit MDO from the lumberyard for my cabinets. I ended up replacing it with Baltic Birch.

Hi MS,
I remember you mentioning this before, but I think you got a bad batch. I've used MDO since 2000 and always been very pleased with it -- even for projects that lived outdoors.

Gary
 

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Hi,
I'd consider MDO (Medium Density Overlay) plywood. Its a high quality plywood that is laminated with water resistant glue and then overlaid with a resin impregnated fiber face sheet.
This sounds a bit like phenolic plywood which I read about. IIRC, phenolic plywood was hard to find in the US, but more common in Europe. Comes in colors and such, so you don't have to finish it.

Ran across it looking into thin phenolic panels for cladding/paneling. Seems they make bathroom stalls out of the stuff mainly.
 

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I see the phenolic ply at woodworking stores for making tool table tops. Frightful prices for small heavy pieces. It would indeed be a phenomenal floor.
 

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Found this stuff on Menards' site which is semi-affordable:

https://www.menards.com/main/buildi...7-c-13341.htm?tid=-5154104427189079133&ipos=3

It's got some layers of poplar and birch so seems better than the softwoods used in the MDO that I've seen. Its intended primary use is for concrete forms.

I'm nowhere near a Menards :( Poked my head in one while traveling in South Dakota and I feel regionally challenged. I have to go on a road-trip for 1" Polyiso if I end up using that on my ceiling, so you never know.
 

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Not a bad price considering what it is. I have to laugh tho they say good for 7 or 8 pours. I don’t know of a single foundation contractor that would discard a plywood form after 7 or 8 uses more like a few hundred minimum ;)
 
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