Floor Composition & Construction for Camper Van Build 

I don’t fully agree with the second point at all, yes if you’re an idiot but if you’ve got to this point and you’re dinging it up to the point of sanding it back down then you’ve got no hope, towels, plastic sheets and a little care and I think like when fitting a kitchen getting the floor done like this is perfect

@@Twink_Twins And I would disagree with both. What is the point of sheet flooring underneath a cabinet with drawers installed? Decorative flooring last. You'll still want to seal around any cabinets so that errant water spills can't get under them. And it isn't only idiots that mar floors during construction, otherwise the flooring contractor in any home build would be happy to have to not cut in around any cabinets and would expect the "non-idiots" to keep his flooring nice for the new owners. There's a logical order to construction that has been proven over hundreds of years. For anyone TALL trying to preserve van height, no reason to give up 1/2" for XPS foam board at only R3 to say nothing about it being a horrible idea as support below a subfloor. Instead, use sticky backed Duct Insulation from Home Depot, which at only 1/8" thick, is ALSO R3. Cut strips to fit in all the low valleys of the floor, then roll a 2nd layer out over the entire floor, which means that around 50% of the floor will be R6 with its TWO layers of it, and about R1 for the single layer, which averages out to >R3 overall, while only yielding about 1/16" of vertical when compressed. Now you have both a vapor barrier and insulation value in the floor. Then, under cabinets and optionally in the garage area you can do another layer of insulation if planning to spend significant amounts of time in cold climates where obviously anyone would be planning to have some form of heat, starting minimally with a Chinese diesel heater for $130. There just is no reason to ever build a subfloor supported ONLY by XPS insulation. And by instead putting 1/2" plywood directly onto the 2nd layer of duct insulation and using rivnuts to fasten it down located barely off the edges of trafficked areas to not impact the vinyl flooring, you preserve maximum floor to ceiling height and avoid inevitable compression of a foam board under traffic areas risking flexing or squeaking. The absolute best way to cut foam insulation board is with a hot knife (about $26 on Amazon). This can then also be used when insulating the walls with foam board to do instantaneous cut and fit trials until you match each area the best. No cutting dust going into the environment at all. As mentioned, a spline or other method should be used to achieve a solid connection between edges of sheet goods in a subfloor. That can be achieved without the special tool requirements for a spline by being as simple as a 2" wide strip of 1/2" plywood fit so that 1" reaches under each sheet and gets glued to them. Then simply open a 2" channel in the XPS board to allow for the double thickness. Put down 1 side of the plywood to be joined, lift and slide the 2" strip under and into place and trace the necessary cutout to the XPS board for the exposed area and lift the plywood sheet to trace the other half. This would have also eliminated the problem of learning that XPS board is not solid enough to support a foot traffic area, particularly where two plywood sheets meet.

@@gianttravelsbyvan9670 hi, I just wanted to jump in on all the disagreeing going on and mention that compressible foam before a floor is going to be more like R-0. Also, what's with 1/2 inch plywood if we're so concerned about height and - I assume - weight?

Biscuits in 1/2 inch ply worked great for me. Just make sure it is over 7-8 ply and you will be fine. Baltic Birch is best. Cheers

That isn't necessary as the plywood is not touching any metal surfaces. The plywood strips however could use some sealer as they are touching metal.

I was thinking the same thing! A natural teacher.

Retired college professor here: I concur! Wouldn't building out a van be a great course? 😁

Absolutely! I've seen so many good van build videos, but never one showing a side view, diagramming the "strata" of the floor. So creative!

"Instid". Interesting dialect on certain words.

i know right

He stated near the start of the video that the strips are just under half inch (15/32") - quite thin as you say. I would be using something closer to 3/4". But he was also trying to have them level with the metal floor ribs; I can see the logic in his approach.

I think it would have to.

@@MAXIMUSMINIMALIST that was a late reply... But still thanks! One year later I agree with what you said. We opted to make sure everything can breath as good as possible! Didn't like sealing of anything either.

wondering the same thing

I read this and decided to use TRIMFINITY 1-3/4-in x 8-ft Polystyrene Lattice Moulding for faring instead of wood for the first layer of the floor in my E350. I am going to hold it all down with bolts that fasten to the floor through the vinyl, plywood, and rigid foam insulation using the threaded holes where the seat base brackets went. With the price of lumber right now, these are cheaper, more moisture resistant, and last longer.

@@MoserMakes Agreed on both thoughts Sam.. When it comes time for me to do a van build, I definitely use your floor ideal with wood slats, just ingenious! OK, another question.. Why Thinsolate Insolation instead of like WoolWorx (Rockwool Acoustic Insolation by Roxul)? Mark...

Mineral wool / rock wool is not environmentally friendly and can be hazardous to your health. Be careful. Actual sheep's wool is being used on some vans, though, for insulation.

Depending on the quality of the plywood, clear coat or stain and sealer would be options Link. Some ply is made with football shaped inserts that replace part of the wood layer where knots were and left holes in the layer. A finished floor of engineered wood would be an option here as well, however I would strongly recommend a brand with a really good integrated foam backer to avoid transmitted noise, to act as a thermal break and to maximize the floor's life with the subfloor moving and vibrating.

Be careful with spray foam. It is open cell foam, which means it will absorb or wick water thru it. It does make reasonable insulation but its primary purpose is to stop air movement. It will have little to no effect on sound beyond perhaps stiffening sheet metal to dampen vibrations. For that it is better to use "mass loaded vinyl" or the normal sound deadening materials used in car audio.

Sylvan Butler I was originally attracted to it because I read that it’s a excellent vapor barrier. I’m very concerned about mold/mildew under floors or in my walls. Especially since I will be drilling a lot of holes. Got any advice about that?

@@abigailv5347 I just tried and failed to find a reference on 'Great Stuff' foam being open vs. closed cell. In fact, one post on reddit vanlife showed good results after peeling off Great Stuff as opposed to other places without it. Great Stuff looks like it would be fine. The key is you want a closed cell polyurethane foam. (not open cell, not latex)

Sylvan Butler thanks for the tips 🤙🏻

@@Sylvan_dB All foams absorb water. Single part foams do not cure in the middle & have large non-insulating bubbles inside. As a test, I filled a cardboard carton with single part foam & sawed it in half a month later. It was hollow & the uncured foam inside stuck to my saw 'forever'. When we renovate flat roofs & boats, the closed cell foam is always heavy as it is full of water.

That's a good idea running the vinyl up an inch on the sides! Thanks for sharing

While more expensive, you can consider marine plywood (very high quality) and balsa plywood (lower weight).

I see no reason to discourage it. It’s bonded above and below. Even if it release it has no where to go and still provides support. It is possibly over-kill though. I like over-kill.

If you go to Bob Wells's (cheaprvliing) van assembly guide, he says spray foam tends to trap moisture and eventually lead to rust.

I’m sure it would. It just cuts that much extra off your headroom in the van. Cheers

Could. Requires prep work and those dents are inna high traffic area. Bondo isn’t designed to adhere in such situations. The fix shown is an eloquent, professional solution.

Hello Moser Makes. I would like to know this as well

How could water get under a sheet of vinyl? No seams, thoroughly sealed edges?

@@abigailv5347 Nothing is ever perfect. (I would *not* have bothered with reflectix either. I don't think it adds value. The vinyl floor is also a vapor/water barrier and so is the pink foam and that is already one barrier layer too many.

Took your advice and am going with TRIMFINITY 1-3/4-in x 8-ft Polystyrene Lattice Moulding for the faring.