Uneven floors... Leveling compound?

[kbeefy]

I'm building a work van into a camper van. (2004 E350) It's obvious that it had some heavy loads in the back.
There are some depressions in the rear floor.... No dents or creases, but some 1/2" depressions.


I'm planning on floating 1" poly-iso foam insulation (pink foam boards) covered with 1/2 or 3/4 plywood for flooring. I would like to level (at least somewhat) the depressions with something.


Any (easy) suggestions? Painted metal floor. Probably decent temp swings. Likely eventual water intrusion. I just want the subfloor to be mostly level and not creak or move a lot. The whole floor doesn't need correction, just a couple areas where I plan a walkway.

[N147JK]

Can you pound them out from underneath? No fill necessary.

[The_Vermonster]

I used a 2x4 and a jack to get a lot of the dents out of my floor. Just round the corners off a little bit with some 80 grit sandpaper so you don't add any sharp dents.

If you're putting an inch of foam and 3/4 ply then you won't notice much of anything of the original floor unless it's in really bad condition.

[doublevan2]

Certainly not an expert in anything - but can't envision anything "leveling" related that you could pour onto metal that would "stick" in place ? Tninking eventually due to moisture - bouncing around on roads and van flexing that would stay in place ? Vermontmonster seems to come closest to a possible solution --

[posplayr]

I bought a 2002 E-250 work van, and the floors sound similarly beat up.
PL300 is specifically formulated for the pink foam board which is easily cut and sanded (flap wheel) into shape. Glue the pieces in place and put a section of plywood and weight over the top so the adhesive can dry.

I have used the PL300 to glue rigid foam to the van roof using a similar technique but used PVC pipe and a floor jack to pressure the plywood into the curvature of the roof.

https://www.homedepot.com/p/Loctite-...1941/202020476

I have debated the next recommendation myself, so just take it as an option. But after reading that you can put 3/4" T&G Ply right over 4" rigid foam board no batting) I don't see why this would not work out.

Rather than put 1" of rigid foam down on the metal floor, with perhaps one layer of radiant barrier on top (with batten boards in the floor grooves), you could instead

0.) cleaned prepped (foam filled dents) and painted floor
1.) install precut 5/8"x1/2" BedRug VanTred Cargo Van (Rubber)
2.) 1/2 R-tech foam board with metalized side facing down
3.) Radiant barrier glued down to top face
4.) 3/4" T&G Ply

BedRug VanTred Cargo Van Mat 1992-2013 Ford E-Series
Part Number: 124-VTRF92X

https://www.homedepot.com/p/R-Tech-1...0810/202533656

The rubber mat will give a good R-value perhaps as good as the 1" foam by itself (due to air pockets; solid rubber has a lower R-value than foam). The 1/2" R-tech could be increased to 1" but more importantly you have an opportunity for double metalized radiant barriers that are separated from the metal floor.

Total stack height

OP Proposed:

1" Ridgid foam
3/4" Ply
----------
1 3/4"


Pos Proposed

1/2" Rubber Mat
1/2" (or 1" Rtex with double radiant barrier)
3/4" Ply
-----------------
1 3/4" (2 1/4" with 1" rigid foam)


I assume you need 3/4" ply to screw cabinets into the floor and the 3/4 ply is bolted to the floor with large washers to keep the whole thing from ever lifting.

[1der]

I like the 2x4 and jack idea.

I probably would not address any depressions I could not easily get to from underneath. 1" poly-iso will require some layer between it and the metal floor to deal with the squeak potential. A layer of 1/2" or 3/4" multi-ply should do a good job of spanning some unevenness.

What you might want to consider is and check is the "levelness" of the floor from the cab area to the rear doors and side to side. Using a 5ft and 8ft long stiff flat edge with a level will show just how non-flat the metal floors really are! I expect you will find it is arched in the middle.

If you want a truly flat floor to start with, consider shimming under or over the polyiso using pieces of various thicknesses of plywood. I have found the need for about 3/4" of shim across the rear door threshold and side to side near the walls to have a flat surface.

A truly flat floor makes the build out of the cabinets and counters more precise and square. Once the shimming is done all the depressions will have been resolved in that process.

If you get a chance to post up some pics of what you find regarding level of the metal floor, I think it would be helpful for others. I realize I did not do this the last time I totally re-built Beastie's interior. I was trying to figure out why my five foot long counter was arched after I had been very careful about the height of the supporting cabinet panels. I was really surprised at how much arch was in the metal floor of a well cared for van!

[1der]

Posplayr's recommendation for the bed rug is a really good one. No need for "battens" or fillers in the grooves, still air is a fantastic insulator.

For clarity, never lay any aluminumized material directly onto the van metal floor. Any moisture that gets in there (and it will) creates an electrolysis that will eat through the floor paint and into the metal. Rust will then eat away at the exposed metal.

And regarding bolting/screwing the plywood floor to the metal floor - remember every fastener is a potential sound and thermal conduit. Additionally, the rigs flex and twist. A plywood floor that is bolted to the metal floor will be unable to flex. A cabinet that is fastened to both the walls and a hard fastened to the hard fastened floor will have to take all of the stress and flex which in time will cause the cabinets to squeak or loosen.

My approach (if doing cabinets) is to tie all the plywood floor pieces together horizontally with plates and use wedges at the pinch seam to hold the edges down. The cabinets bolt/screw into the floating plywood floor and bolted ledgers running along the walls at proper heights. This allows for very secure cabinets that use the walls as the single connection to the van body and, the cabinets hold the "floating" plywood floor in place. As the van flexes the floor will be free to absorb that flex with minimal stress on the cabinet joints.

If you are installing seats with seat belts, motorcycle or other hold downs, then you will be fastening those through the plywood to backing plates below the metal floor. That in itself will hold the plywood down.

[posplayr]

Originally Posted by 1der

If you want a truly flat floor to start with, consider shimming under or over the polyiso using pieces of various thicknesses of plywood. I have found the need for about 3/4" of shim across the rear door threshold and side to side near the walls to have a flat surface.

A truly flat floor makes the build out of the cabinets and counters more precise and square. Once the shimming is done all the depressions will have been resolved in that process.

It would seem that a 3/4" shim at the rear doors might be equivalent to a 1/2" (or less) shim under one of the cabinet feet. In other words, shimming a cabinet will require less shim and certainly preserve more headroom in the process.

The walkway between cabinets is probably only 20" wide and the longest cabinet might be 5 feet long.

The point is that a truly flat floor is not necessary and would only be noticeable in reducing the floor-ceiling height.

[1der]

Originally Posted by posplayr

It would seem that a 3/4" shim at the rear doors might be equivalent to a 1/2" (or less) shim under one of the cabinet feet. In other words, shimming a cabinet will require less shim and certainly preserve more headroom in the process.

The walkway between cabinets is probably only 20" wide and the longest cabinet might be 5 feet long.

The point is that a truly flat floor is not necessary and would only be noticeable in reducing the floor-ceiling height.

One could also measure and cut cabinet walls to plane out for a level counter and compensate for the non square angle between a non flat floor and cabinet walls which want to be plumb and parallel. Going to deal with flat and level somewhere in the build. Always compromises! The 3/4" on the floor helped provide a bit more insulation there. In our build we do not miss the 3/4" of height right at the back doors. I did appreciate the 52" tall cabinet being plumb though! ymmv!

[kbeefy]

I will probably use a jack to try and flatten it out as best as I can then shim the floor flat. Thanks for the tip on a long straight edge @1der.



I had seen the bedrug before... does it actually add any R value? I wasn't planning on using any battens on the floor, but just let the foam bridge the floor ridges. Maybe some butyl sound deadening in the troughs, though I think in that area it's probably a waste of time. If the bedrug is beneficial that would make things easier.


I had planned on gluing the poly to the floor and the gluing the subfloor to that, using PL300. I assume the bedrug would not fit well with that plan? Will the PL300 stick to rubber as well?