Installing the Subfloor

Installing the Subfloor

April 25, 2015 Categories Camper Van

I finally got around to starting on the flooring in the She-Beast today. I’ve been distracted trying to ensure the cab area isn’t leaking water (which it still is), but it has irritated me to the point I’ve decided I just need to move on and come back to it later. The driver’s door isn’t sealing correctly and is letting water in, but the weather seal looks in decent shape. It’s almost as if the door itself is bent outwards just a smidge.

I started the subflooring by filling the gaps between the ridges in the sheet metal on the floor of the van with strips of Reflectix (which is essentially bubble wrap with sheets of tin foil on each side). Reflectix only has an R-value of about 3, but almost every camper van conversion project I’ve read about uses it because it’s good at keeping cool air inside when it’s hot out and keeping warm air inside when it’s cool out.

Once I had the gaps filled, I laid down an entire sheet of Reflectix insulation to cover the entire floor. The most important and time consuming part of this was cutting around all the pillars, gas tank filler tube, and the wheel wells; I wanted as close of a fit as I could get. I used aluminum foil tape to seal the joints between the different sections of insulation, as it only comes in 48″ wide rolls. The wood blocks in the photo are just to weigh it down and keep the wind from blowing it around.

Now that I had the insulation cut and in place, it was time to prepare the plywood that lays on top of it. I laid out three sheets of 1/4″ OSB to create one giant 12’x8′ rectangle. The Reflectix layer I just cut created a perfect template to lay directly on top of the OSB and trace out using a marker, as you can see below.

With the template traced out, I put the Reflectix insulation back in the van. Then I grabbed the jigsaw and started cutting (beginning with the sheet that sits directly behind the seats). As I finished cutting each sheet, I went ahead and installed it in the van. Since I had a great template, each sheet slid into place very nicely. It didn’t take too long to get them all cut and laid into place. I used self-tapping sheet metal screws along the walls to hold the plywood to the floor. I didn’t put any screws down the center because the screws don’t sit flush and I can’t recess them since it’s only 1/4″ thick OSB (they’d break right through).

Now that I have the subfloor in place, I can start laying out everything else. The entire rear half will have another level of flooring installed that will sit about six inches high to allow enough room for my storage system to go underneath it. Even with the raised floor, I can still stand up straight in the rear half. However, once I insulate the ceiling and board it up (which will take up 3-4 inches), I’ll have to tilt my head just a little in that area. Since that will be my couch/bed area, I won’t be standing there much anyways. I’ll still have four feet of space in the front half where I’ll be able to stand up completely and stretch out.

23 thoughts on “Installing the Subfloor”

Jacob · April 14, 2016

Good job! Smart way to trace the ply to get it right the first time.

Beth · April 24, 2016

Great step by step! I will be following your idea for my own trailer mod.

Jon · August 23, 2016

Great and easy to follow! What was the overall cost in transforming the van to a livable area, from insulation to curtains?

Luke · August 23, 2016

Because I went way overboard, it cost over $7,000 for everything I did. And that’s not including the cost of the van. The entire electrical system by itself was around $2,300. Some stuff I never even used, like the water heater and portable furnace. Other stuff I only used a few times, like the microwave, stove, and refrigerator.

The solar setup, running water, and the wall-mounted fans that I eventually added are the only things I know I’d do again, as those were luxuries that were nice to have, especially while living out in the desert for a couple weeks.

Lucas · September 17, 2016

I loved the idea for the template using the insulation. What kind of screws did you use to fasten the plywood to the new floor? I am in the planing stage to convert an 02 Chevy Astro AWD:) Being that I only spent 2k for the van I am not going to be spending too much on the interior. I am going to be scrounging supplies over the winter here in the Twin Cities and stock piling them for spring:)

Carey · February 9, 2017

Hey Lucas, I’m doing the same thing! Like actually the same thing. I jut bought an Astro van for 2 k and am building it out at low cost. What plans did you come up with?

Thomas Buzzi · March 7, 2017

Just did the same operation myself. I used pattern felt I had lying around from my floor covering days to cut out first the 1/2 styrofoam with bonded aluminum layer and then used that to pattern some 5/8 plywood I also had lying around to keep costs down. I can’t stand up anyway since it is not a turtle top van. Will use foil backed side wall insulation too but not the roof since aluminum foil blocks cell phone reception. (Found that out the hard way).

Claire W · March 15, 2017

Do you find that the bubblewrap-foil insulation was enough? or would you have also added a rigid thicker type of insulation?
I’m just about to start my conversion project, and insulating it is one of the first things on my to-do list.

Luke · March 20, 2017

I would have done a lot of other things differently, but the insulation was more than enough for me.

David Albright · April 23, 2017

Please just do ONE thing. Use PLYWOOD, preferably pressure treated or marine grade. For the area it is not much more expensive. OSB swells and falls apart if it gets wet. You can thank me later!

Luke · April 23, 2017

If you’re expecting water to be freely sitting under/on your floor, you’re already doing something wrong. If you build something properly, you won’t have to worry about water being where it’s not supposed to be.

Richard Chambers · June 11, 2017

You might want to consider the chemical exposure from the treated (CCA) https://en.m.wikipedia.org/wiki/Chromated_copper_arsenate

At least unhealthy using treated lumber indoors.

Terressa · April 26, 2017

Did you use the sub flooring itself as the floor or did you put flooring down over it? You could have sanded the sub floor to smooth it out, stained it and put a sealer on to make awesome faux hard wood floors.

Luke · April 26, 2017

I put flooring over it. I don’t think I’d like the look of sanded and stained OSB. I wanted a rustic look.

Terressa · April 26, 2017

Just finished all the articles. BEAUTIFUL!!!

Scott in MN · May 1, 2017

Wrong use of Reflectix. Manufacturer states that a 3/4″ air space must be used or product is essentially worthless.

Luke · May 1, 2017

Hot damn, that’s good to know! And would help explain why my van was an oven. For anyone who wants the information from the source, go here http://www.reflectixinc.com/about-reflectix/frequently-asked-questions/ and click on “Why are Air Spaces required (in every application)?” or watch this video: https://www.youtube.com/watch?v=E1IwS0_lpBc

Alex · May 13, 2017

Awesome step by step. I am just curious how you finished off the step by the slider door?

Luke · May 13, 2017

I didn’t. I was going to, but got impatient and just wanted to start traveling, so that’s what I did.

Roger · May 26, 2017

So, if Reflectix is not suitable because it requires an air gap, what should be used?

Tammy · June 5, 2017

How do you achieve the air space?

Luke · June 11, 2017

Google.com

Daniel Chen · June 17, 2017

One of the best online visual explanation on sub floor install for a layman like me.

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