Van Floor Insulation XPS and Dacron

[BinDerSmokDat]

I've been giving a lot of thought to what I will use on my floor for my van build.
I'm planning on the coldest camping being fall and spring nights, no overwintering in sub 40F temps.
I also have an 8-10 year plan for this vehicle so I want to do it once and done. No going back and ripping shtuff out later.

I am currently leaning towards the following in the order they are installed....

Stock steel painted floor, some minor surface rust sanded away, etching primer, painted and scuff sanded with 60-grit.

Durabak polyurethane bedliner in several coats applied up walls as high as wheel wells (two gallons for whole van floor firewall to rear cargo doors).

1/2" to 3/4" Bonded Dacron Batting (have to see depth of channels formed by floor ribs after Durabak is applied)

3/4" Dow Formular aka XPS aka pink board

15/32" BC fir plywood, all edges and faces urethane sealed.

My rationale is thus...

The steel floor will conduct sound and temperature to some degree.
To provide the maximum wear and rust resistance as well as some acoustic dampening, I'm applying Durabak.
The Dacron will insulate between the floor ribs where it can expand somewhat, compress on top of the floor ribs to provide a barrier to XPS squeaking. In addition Dacron is non-wicking and breathable. It shouldn't wick moisture in and it's breathable to allow any condensation that forms the opportunity to escape at the ends of the van ribs, which will have some breathing space. Also by filling the ribs with Dacron, this should prevent dirt and dust from migrating it's way down the channels.
3/4" XPS provides the bulk of the insulation power and also some sound damping. 
1/2" ply is sealed to prevent moisture absorption and improve dimensional stability, while being thick enough to support loads and strong enough to tie into walls via batten blocks attached by screws form the underside. I have a floor plan in mind that will minimize seams in the bare areas of the floor (including a local source for 10' length ply!)

Since the batting will compress on top of the ribs, the Durabak will add somewhere between 3/32" to 1/8" I'm figuring that this will eat about 1.33" of height.
I can go down to 1/2" XPS if need be to gain height but I don't think it will be an issue.

I've thought about doing the same exact thing WITHOUT the Dacron, but I like the idea of the added insulation/sound dampening, as well as preventing dirt from entering the channels created by the ribs.

Comments? Advice?

 

[Almost There]

My opinion - If you're not planning on any nights below 40 F then there is no point in spending all that money on various methods of insulating the floor.

I have 3/4" plywood in the floor covered by vinyl laminate flooring. Throw rugs and either my shoes or slippers provide adequate warmth down to about 40, the heater provides warmth whenever needed. I used 3/4" so that I could get a firm grip with the screws that hold all the cabinetry to the floor and for no other reason.

The bigger problem is excessive heat - either because of residual heat from the exhaust system or being parked on hot pavement in a parking lot. Once parked, the pavement is shaded and cools down and residual heat goes away. Neither are problematic enough to cause me to wish I had done the floor differently.

I just googled Dacron batting and IMO, it's going to collect dust and dirt like crazy. I realized I've used it before in upholstery uses and it's not really useful as anything but a comfort addition in seating. A couple of years down the road it's going to be so compressed as to render it useless.

Sound deadening is controversial...my opinion - it's a van, it's not a BMW, it's going to be noisy to some extent. Sound deadening the floor without going to the same measures 360 degrees just means that it's a different sound coming in from somewhere else.

Practice turning up the stereo...

Once you've got an interior built in there will always be noise from contents of your cabinets, wood squeaking etc. anyways so don't expect a luxury sedan quiet ride!

If you've got rust spots on the inside of the van, by all means treat them with your pick of rust treatment but putting in 2 gallons of bed liner might be taking it beyond what's necessary.

If you're going to be putting pink board in the floor, then I'd lay down 1x2 laid on it's wide side on 24" at least, (closer would be better in high traffic aisles) centers and lay the board between the framing. This will prevent the deterioration of the pink board caused by weight, particularly human weight.

Advice - put that money in to something else you  need more!

 

[John61CT]

I think that insulation is very important, and the lighter the better. Therefore I don't like plywood for anchoring purposes.

Rather than raw screws, I prefer PlusNuts, bedded with butyl and holes sealed with galv paint.

I would use bolts into those to lock down loads from shifting, maybe L-track if that location flexibility is desired.

I think any thin foam will do if you think something really is needed between the ribs.

For sanitation purposes, again, if you think that's important, I would prefer to be able to just pull everything out and up and give the steel floor all nooks and crannies a good clean.

Ability to check for rust issues is a major plus.

 

[grandpa pete]

save your money and use rustoleum rusty metal primer coverer with rustoleum paint ; no peeling later .

 

[BinDerSmokDat]

Thanks everyone!

Sound deadening IS important to me!
My daily driver is a 2016 CX9 that Mazda went to great lengths (53 pounds more sound deadening material than the previous generation and thicker windshield and window glass) to make it quiet.
I know that the van will never be as quiet as that, but sound, rattles and squeaks have a deleterious effect on your well-being whether you realize it or not.
I ride motorcycles and wear earplugs. People think it's "dangerous because you won't hear traffic."
In reality it screens out a lot of the loud wind buffeting and droning engine and tire noises and lets you hear other traffic better.
It's also less fatiguing on long rides; continuous sound wears you down mentally.
When I drove my van 4.5 hours back from VA non-stop, I definitely felt more worn out and jittery from all of the noise.
Turning the radio on masks some of the distracting sounds but it is also increasing the overall noise levels.
Also when the van is parked I want to minimizes outside noises (car doors slamming, rain on the roof, generators) as well as minimize interior noises being heard outside (watching TV, talking).

I bought Noico sound dampening material for walls and ceilings (possibly interior wheelwells), but I'm not sure how it would hold up on the floor so that is part of the reason I'm using the Durabak bedliner on the floor.
I know from my experiences with Jeeps, where I've permanently removed carpet for easy of cleaning, that bedliner makes a difference in interior sound levels.
And that is in a soft-top/open-top vehicle with all-terrain/mud tires. I also want a floor solution that lasts 8-10 years with no worries about rust or ripping up the floor.
The floor had just paint on it and has held up decently but with the back of the van currently stripped, noise is a big issue, even with a layer of double corrugated cardboard taped down.
So I'm pretty sure the Durabak component of my floor system is staying.

As for the Dacron batting I'm not married to it, it's just another layer of possible sound and thermal barrier.
I know it will compress along the tops of the ribs of the floor, but it won't compress with time in the channels.
It is pretty resilient stuff and I've used it before.
I've recovered items I've upholstered that were under tension from the vinyl covering plus sat on for years and the batting is still standing tall.
I wouldn't think it would accumulate a lot of dirt as I hope to have a near seamless floor in the traffic areas. But definitely something to think about.
XPS is also pretty resilient to compression, especially when you consider that it is used on the back of many floating floor systems to provide both a thermal and sound break.
On the 6-8" centers of a van floor, it should hold up OK. The use of 1x2 furring strips means holes in van floor, something I'd like to avoid entirely.

I like what John61Ct was saying about being able to give the floor a good clean.
I was already going to use Plusnuts on the walls and ceiling for anchoring and holding heavy loads.
Maybe I will rethink my anchoring system so that all furnishings tie into the walls and I can remove the flooring for cleaning/inspection.
That changes my "seamless" floor idea I mentioned above, but gives me the option of seeing what is going on.
It also allows me to try the Dacron, see how it holds up and remove it later.

Not using plywood at all...that means either an all-foam floor or a bare ribbed floor with possibly rugs/carpet or foam in ribs to get a flat layer and thin foam then carpet.
All ideas I had not considered. I'm kind of thinking I want a hard, sweepable surface. Also it has to look nice, I have a wife after all.
Though if everything is anchored to walls, then floor sections made of XPS foam and 1/4" Luan bonded together become an option.
I could use vinyl flooring on them and make them like large removable floor tiles.

I don't like the idea of a full-time piece of carpet/rug, even though they are cheap and easy for adding sound dampening and comfort.
First, they are dirt magnets. Better to just give the van a quick sweep every day or so.
So far my short trips camping in the NJ Pines (read: sand everywhere!) have taught me to use a small carpet as a welcome mat/porch outside the van for minimizing dirt and sand intrusion.
Currently I can also use a small wisk broom to sweep out the van front to back in just a few minutes.


I will also rethink my insulation needs considering my expected temperature ranges. I had already given a thought to heat from the exhaust . I've noticed the floor can get quite warm over the exhaust. I'm considering some heat shielding on the underside of the van. I'm thinking thin aluminum flashing supported by, but standing off of the frame/body rail. I'd use existing holes in frame and body flanges. And I like my summer camping but need to be cool to get to sleep. I frequent a few places with hook-ups so a small AC is not out of the question at this point of the design process. More insulation means it will run less plus as it will be outside of the van, more insulation and sound deadening mean I will hear it less.

Thanks again everyone! All good ideas to think about.

 

[John61CT]

You're more detail oriented than most of course, but it all makes sense to me.

There's no problem tying in cabinets to walls or roof rather than the floor where that makes sense, just note if it makes more sense to do so to the floor, e.g. a big lead battery bank between the wheel wells, don't worry so much about putting holes in the floor, treat edges with zinc galv paint, properly bed down the PlusNuts in butyl - there really is no downside, everything is water / gas tight.

Same with mounting even structural heavy stuff to the roof or side body panels, that's exactly what they're designed for, going back to WWII, originally in military aircraft.

The first time you cut out a big old hole in a nice shiny roof for a vent fan it seems heresy, but really, no biggie, for the best.