Floor Installation in a Camper Van Conversion

Van Conversion Floor

Floor Installation in a Camper Van Conversion

And now is the time to install a floor in our van conversion! A floor has many other critical functions than just supporting our feet. Indeed, a proper floor installation prevents water infiltration (= rust), provides thermal and noise insulation, and serves as anchor for the cabinets. In addition it should be resistant to wear, be able to withstand enough weight, not produce any squeak and … look good (yep, that counts!). There are many ways to install a floor in a van, but keep reading to learn our take on it!

Last Update: January 2020

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Portrait

Time Spent

0 HOURS

Total Cost

$ 0 USD

Material: 3 Seasons

Good for occasional sub-freezing temperatures.
LAYERITEMQUANTITYLINK
1 & 2Minicell Foam7 sheets eBay
3Preferred: Baltic Birch Plywood (½”, 4’x8′)3 sheetsCheaper to source locally
Alternative: Exterior Plywood (¾”, 4’x8′)
4Vinyl Floor13′ wide x 8′ longCheaper to source locally
0/13M 90 Spray Adhesive1Amazon
3/4Vinyl Floor Adhesive1Amazon
 Wood Filler (only if using exterior plywood)1Amazon
 Silicone II (for caulking the vinyl floor periphery, step 7.6)1Amazon
 Great Stuff “Gaps & Cracks”1Amazon
 Vinyl Floor Seam Sealer1Amazon
 Stair Edging (1-1/8″)1Amazon

Material: Snow Chasing

1" thick XPS for Full-On Snow Chasing!
LAYERITEMQUANTITYLINK
1Minicell foam3 sheets eBay
2
XPS foam (1″ thick, 4’x8′)3 sheetsCheaper to buy locally (product example: Insulation4us)
3Preferred: Baltic Birch Plywood (½”, 4’x8′)3 sheetsCheaper to source locally
Alternative: Exterior Plywood (¾”, 4’x8′)
4Vinyl floor13′ wide x 8′ longCheaper to source locally
0/13M 90 Spray Adhesive1Amazon
1/2Silicone II3Amazon
2/3PL300 Foam Board Adhesive2Amazon
3/4Vinyl Floor Adhesive1Amazon
 Wood Filler (only if using exterior plywood)1Amazon
 Great Stuff “Gaps & Cracks”1Amazon
 Vinyl Floor Seam Sealer1Amazon
 Stair Edging (1-1/8″)1Amazon

NOTES:

  • Minicell thickness: Transit = 0.40″, Sprinter & ProMaster = 0.30″. Choose thickness in eBay store.
  • Quantities shown are for our van (Transit extended-length) and may varies according with your van model. For Minicell quantities, follow recommendations in product description (eBay store).
  • We used ½” XPS (in pink) to fill the corrugations, but we would use Minicell if we had to start over. Read our “Second Thoughts” at the bottom of this page for more info!

Tools

ItemDescriptionQuantityLink
Snap-Off Utility KnifeStanley 18mm.1Amazon
Caulking GunFor 10 oz cartridge.1Amazon
Jig SawDEWALT Cordless Lithium-ion 20V.1Amazon
Blade Set for Jig Saw14 Pieces.1Amazon
Circular SawDEWALT Cordless Lithium-ion 20V, 7¼ with brake.1 Amazon
Circular Saw BladeDEWALT Precision Finish Blade 60 tooth.1Amazon
Trowel1/16″ x 1/16″ x 1/16″ Square Notch.1Amazon
Rolling PinTo roll tasty vinyl pies.1Amazon
Painters TapeTo protect the van walls when working with Great Stuff Foam.1Amazon

Good To Know

Floor Layers In A Nutshell

Layer 1: To Fill corrugations

  • Provides thermal insulation (and sound insulation to a certain extent).
  • Increases support surface for LAYER 2.

Layer 2: Top of corrugations

  • Provides thermal insulation (and sound insulation to a certain extent).

Layer 3: Underlayment

  • Provides a smooth and level surface for good adhesion of the finish layer.
  • Supports and distributes weight.
  • Serves as anchor for cabinets.

Layer 4: Finish

  • Looking good!
  • Protects against liquid infiltration (and therefore, rust). Trust us, spills WILL happen! That’s why we went for large vinyl sheets (2), instead of multiple vinyl tiles (to minimize seams).
  • Shall be wear resistant.

Choosing A Plywood

Baltic Birch

The plywood underlayment shall be moisture resistant, exempt of any warp, and the surface common with vinyl flooring shall be nice and smooth. That’s why we prefer Baltic Birch. It is laminated with exterior grade adhesive, it’s straight, the surfaces are smooth (no wood filler needed) and it’s very dense (screws grip better in it). As a result, ½” should work well. Note that we wouldn’t treat the entire plywood sheet: just the edges. Indeed,  it is sandwiched between the vinyl floor and the foam (XPS or Minicell), so it’s not exposed to high level of moisture or condensation.

Exterior Plywood

Exterior plywood commonly found in hardware stores are glued using exterior grade adhesive and some of them are also treated for protection against fungal decay, rot and termites. Compared to Baltic birch, it is made of thicker plies so less plies are needed to obtain the same thickness. Therefore, the resulting plywood is less dense and warp more easily. We’ll go ahead and say that, even if the underlayment is exposed to some moisture, it’s not required to used treated plywood as it is “protected” by the vinyl floor and the foam (XPS or Minicell). If using plywood to fill the corrugations, that’s another story…

Choosing the XPS foam

You’ll find XPS branded as “Foamular” 150, 200 and 250. This number relate to its compressive strength. 150 is capable of supporting 15 PSI, 200 can support 20 PSI and 250 is capable of 25 PSI. Knowing that a human footprint is equals to approximately 16 PSI, it’s a good idea to choose XPS higher than 150 (15 PSI). Note that the plywood underlayment will take care of distributing the weight to a larger surface, so any foam should be OK. That being said, there’s a pretty good chance you walk on the foam during the van build (before installing the underlayment); you’ll appreciate if the foam does’t collapse under you 🙂

Attaching The Floor

Believe it or not, there’s no need to secure anything; the floor isn’t going anywhere! The large plywood sheets, combined with the weight of the cabinets (and others) will ensure the floor stays where it belongs. Doubt it? We completed our conversion in 2017 and our floor hasn’t move at all. And many people have use this technique with the same results. 

So, why are we recommending to use adhesive anyway? The adhesive doesn’t provide any kind of “structural” bond: its role is to keep everything where it belongs during the floor assembly & to prevent squeaks; especially with XPS. We repeat, XPS squeaks if not attached properly! Keep reading for recommended adhesives. 

All of that being said, we see a scenario where we would attach the floor to the van: if no cabinets are added to the van and a slide-out-bike-rack is installed. Then, it might be a good idea to attach it (because of the long lever when the bike rack is out).

Adhesive Compatibility

 MinicellXPSMetalWood
3M 90YesNO!YesYes
3M 78YesYesYesYes
3M 77YesMaybeYesYes
Great Stuff (Gaps & Cracks)YesYesYesYes
Silicone IIYesYesYesYes
PL 300NoYesWeakYes

Choosing the right adhesive

Like it or not, there’s no perfect “universal” adhesive (because CHEMISTRY). The “best” adhesive depends on materials, application context, use context, availability and cost. Base on the previous table, here are some options:

  1. 3M 90: This is the stuff we used to glue Thinsulate to the walls and ceiling. Works great, except it WILL attack XPS. Bond time = 15 minutes.
  2. 3M 78: Designed specifically for foam, it’s probably the best option (technically speaking). However, it’s costly and more difficult to find. Bond time = 30 minutes (it means you have 30 minutes to put everything together and apply pressure).
  3. 3M 77: It used to be safe for XPS (polystyrene), but 3M had to change the ingredients recently. We’d recommend testing it before using it with XPS. Bond time = 15 to 30 minutes.
  4. Great Stuff Gaps & Cracks: Not technically an adhesive, but people use it successfully to glue foam. It’s very cheap and easy to find, but it can be messy if not careful. Bond time = less than 10 minutes? (test it, not sure exactly)
  5. Silicone II (not acrylic): Not technically an adhesive, but it works great for the current application (prevent squeaks). Quite cheap and easy to find. Bond time approximately 15 minutes.
  6. PL 300: That’s what we recommend for bonding XPS to wood. Won’t work on metal or with Minicell. Bond time = 20 minutes.

Some don'ts

Framing

We often see people framing their floor, the justification being that it “stabilizes” the floor. Unless if you are using compressible insulation (thinsulate, wool), there’s just no need to do this. The van’s floor is stable enough. Good reasons not to do it: 1- frames are thick and vertical space in a van is precious. 2- Wood is a good heat conductor, so the frames create thermal bridges (in other words, it’s bad for insulation. Check out our “Insulation Guide” for more.).

Metal screws

Each screw added to the metal of your van is a potential ignition point for rust. Knowing that the floor is a very sensitive zone for rust, we really recommend not screwing liberally through it. There can be some exceptions to this (we personally drilled a few holes for the Webasto & Propex heaters, composting toilet exhaust, grey water drain, propane locker vent and floor vent), but the bare metal of each added hole/cutout should be primed + painted to prevent corrosion.

And now let's get to work!

1- Clean Everything:

Cleaning is NO FUN.

Clean your mess

2- Fill the corrugations with the Minicell (Floor Layer 1):

NOTE: We used ½" XPS for this step (as shown in the pictures) which is too thick, so we would use Minicell if we had to start over.

2.1- Cut the XPS (Minicell) using the utility knife.

2.2- Install on the van floor using adhesive (3M 90 adhesive with Minicell).

The XPS Shake:

Put some of the leftover C-200 XPS strips in the blender with vanilla, protein powder, ice cubes and decorate with mint. Enjoy!

3- Install the XPS or Minicell (Floor Layer 2):

3 Seasons = 0.25" thick Minicell.
4 Seasons = 1" thick XPS.

3.1- Isabelle crafted a template from some random brown left overs. It helped making clean cuts on the insulation.

2.2- Add the XPS or Minicell and secure in place using the adequate adhesive (XPS = Silicone II, Minicell = NONE).

We left a gap of about ½” all around the van wall to account for installation variations and to ensure there would be no squeaking noise. This gap will be filled later with Great Stuff.

4- Install the plywood underlayment (Floor Layer 3):

TIP: Use the foam (from layer 2) as a template, it'll save you some time! And don't forget to take your shirt off when using a circular saw.

Isabelle approves the result and the shirtless display.

Secure the plywood to the XPS using PL300 (remember, this is to prevent squeaks) and apply weight. If using Minicell, no adhesive is required (Minicell doesn't squeak).

Cannot find any weight? Leaving a bowl of food on top of the surface to be glued will inevitably attract heavy weight.

6- Before adding the finish layer...

Cavities on the plywood were filled with wood filler and then sanded flush. If using baltic birch, this step is not required as it is already smoothed.

To seal the gap and make a nice & flat surface for the vinyl floor, we overfilled the gap with Great Stuff (Gap & Cracks), let it dry and then trim it flush with plywood sheet (using an utility knife).

Van Conversion Great Stuff Overfilled Flushed

7- Install the vinyl sheet (Floor Layer 4):

7.1- We bought a sheet of 8'x13' vinyl and trimmed it as follows.

7.2- The idea is that we want the seam to be "hidden" under the bed, so it's not part of the living area.

TIP: We were told not to trim the vinyl to it's final dimensions right from the start and that was a GOOD TIP! Work with extra length and do the final trim AFTER it's glued. Indeed, it’s almost impossible that the vinyl will return to the same exact location after the glue is applied (because it will slightly move and stretch). That's why we initially trimmed the vinyl to 6.5', which is slightly larger than its final dimension (~6').

7.3- Follow the instructions on the vinyl floor adhesive: use the appropriate trowel and the right amount of adhesive (not more).

7.4- The vinyl was stretched and bubbles removed using a rolling pin. Notice the extra material around the periphery: that will be trimmed to its final dimensions later.

7.5- Then we proceeded with the second vinyl sheet. To make a nice seam between the two sheets, we slightly overlapped them and trimmed both sheets (simultaneously) so they have the same exact trim. No picture of the seam, sorry 🙁

Floor Installation Camper Van Conversion (4)

7.6- We caulked the vinyl floor periphery with GE Silicone II. Unlike acrylic, Silicone is permanent: it doesn't dry and doesn't crack, it's very flexible and it remains elastic from -55F to 400F.

Floor Installation Camper Van Conversion (Silicone)

8- Install stair edging:

As a final touch, we added an aluminum stair edging at the sliding door, passenger/driver seats and at the back of the van (garage).

Because the stair edging is only 1-1/8″ and our floor is thicker (we went for the "snow chasing" mode!), we added a wood trim that we painted grey to match the van magnetic grey. The wood trim is screwed into the plywood layer of the floor (the screws are hidden by the aluminum edging).

9- OMG WE HAVE A FLOOR!

Floor-and-banana

On Second Thought...

Things we would do differently
  • We initially went for ½” XPS to fill the corrugations and we would now go for Minicell (because it has exactly the right thickness).
  • We initially install a layer of MLV (mass loaded vinyl) for soundproofing, but we feel it was superfluous. This thing is HEAVY and sandwiching it among the floor layers is not how it’s meant to be installed to be effective. So save yourself the trouble!
  • We used exterior plywood and left it in the sun for some time… It warped the plywood big time. Next time we’ll use Baltic birch and keep it away from the sun!
  • This page was updated to reflect how we would do things next time!
How cold is the floor in winter?

Heat rise, right? So we expected our floor to be constantly cold. Turns out the Webasto placement is perfect, as it blows hot air parallel to the floor. As a result our floor is nice and warm even when it’s way below freezing temperatures outside. Neat!

That being said, it might not be the case for different layouts… If your “living area” is in the back and your Webasto in the front, the floor might be cold in your living area. 

Any change over time?

Nope! The floor is still level and doesn’t squeaks 🙂

STAY IN TOUCH!

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about us

Nice To Meet You.

Hello! We’re Isabelle and Antoine 🙂 In 2017 we sold our house (and everything in it), quit our engineering careers and moved into our self built campervan. We’ve been on the road since then and every day is an opportunity for a new adventure; we’re chasing our dreams and hopefully it inspires others to do the same!

111 thoughts on “Floor Installation in a Camper Van Conversion”

  1. I love your page. I am curious about the lack of floor ‘joists’ and use of straight foam board. Since you have now had it awhile, do you find the floor to be soft of squishy? Would you do anything differently in regards to the foam board floor? I am a home building doing my first van build.

    Reply
  2. Hey, thanks so much for this site.

    I’m having trouble reconciling some theory. Like you, I’m in the “let it breathe” camp, but it seems that you’re sealing the floor here by using the Great Stuff Gaps & Cracks, and the Silicone. Wondering why? Wont’ this prevent airflow to the floor?

    I’m currently putting mini cell in the floor ribs of my van, but I’ve had a bit of trouble cutting it to perfectly fill all the gaps. Debating whether to spray Great Stuff in there, or if I should embrace the slop, since it will allow for a bit of airflow?

    Thanks!
    Chris

    Reply
    • – Water (or any liquid) spill is inevitable (it happened a few times during the last 2 years), so we sealed the floor and we’re glad we did. For the rest (walls & ceiling), the breathing “theory” still applies.
      – We didn’t perfectly filled the gaps either, and it’s fine like that; I wouldn’t bother fill it with Great Stuff…

      Happy conversion!
      antoine

      Reply
  3. Great website, i go through yall for all my needs. When you filled the gap with great stuff were you worried about it raising the floor? I have the minicell down then 1/2 in foam in my promaster but it by no means makes a perfect seal where the great stuff won’t get under it. Thank!

    Reply
    • To be honest, I don’t recall exactly being worried or not (about the fact that foam could get under and raise the floor)… All I know is it went well; the floor didn’t raise!

      Sorry I don’t have specific tip… I guess if you’re careful it should work! 🙂

      Good luck!
      antoine

      Reply
  4. Hello, How long did you weight down the plywood for? “Final” cure time for the PL300 says 7 days, just wondering if you waited that long.
    Thanks

    Reply
    • Working time for PL300 is 20 minutes, but we left it overnight. In other words, I’d go for roughly 12 hours. It takes 7 days to reach full strength, but unless you plan on pulling it in the “up” direction super hard, no need to wait for that long 🙂

      cheers

      Reply
  5. Antoine an Isabella,

    First of all…Great Website. Thanks for being so fastidious about documenting you build. Your efforts are saving me a whole lot of brain damage 🙂

    I just obtained a sprinter that shall be converted over the next couple years. IT will be my kiteboarding and ski adventure vehicle. I’m about to install the floor per your design and instruction. One question comes to mind. I am planning to install the Baltic birch plywood you suggest. In you notes you state: “Note that we wouldn’t treat the entire plywood sheet: just the edges.” I’m confused by this. With what are you referring to treating the edges?

    Kind Regards.

    Kevin

    Reply
    • By treating it, we means applying something like polyurethane or varnish. Treating wood prevent moisture absorption or prevent stains. So for the floor, we suggest treating the edges (that’s where you see the layers of the plywood, where you cut).

      Hope that helps!

      Reply
  6. Great information. I’m getting ready to install a floor in my Transit and want to be able to have the option of installing the two seat section of seats that came with the van when we have passengers. I plan on bolting the seat mount rails to existing location on top of the floor using longer bolts. Do you think that I will compress or deform the floor? Some folks build a well in the floor around the seat rails, seems like a lot of work. Your thoughts?

    Thank you,
    Mike

    Reply
    • Generally speaking, a longer fastener is not ideal (because it increases the leverage = weaker joint). A bolt going through all the layers of your floor won’t be very safe… I haven’t install a seat myself, so I haven’t researched how it is supposed to be installed. But if I was you, I would check with seat manufacturers and on different forums as a starting point.

      Good luck,
      antoine

      Reply
  7. Hi there,

    Wondering why you all chose Robert’s 6300 as your floor adhesive. I have a similar setup in progress with fiberglass-backed vinyl sheet flooring ready to be installed over my birch plywood subfloor, the other catch is that I sealed the subfloor with two coats of Spar Urethane for moisture protection. My flooring manufacturer recommends a specific model of IVC, Henry, or Taylor adhesives, yet home depot’s webpage recommends one made by Roberts (2310 to be exact). As far as I can tell, any pressure sensitive adhesive will work on an untreated subfloor, but I am unsure if the urethane will effect the bond. I have contacted all of the adhesive manufacturers and am waiting to hear back. Was just wondering if you all had any experience or know anyone with a similar experience, and what worked for you/them.

    Thank you for you extremely helpful webpage!

    Luke

    Reply
  8. Love your build and your website has been very educational! I’m just starting my own build, doing an all xps floor as you did, but with birch plywood. Quick question, why did you stop the floor Amin front of the D pillars rather than continuing to the very back of the floor and simply leaving a small access for the spare tire mechanism?

    Reply
  9. Hello! I have a question

    I am about to do the flooring for my van and love your approach to it! Seems efficient and weight saving!

    My question is about the layer between the minicell and the XPS board. Does the silicone II keep it attached to the minicell? Or should I/can I use 3m78 (cost willing) along with it to have more of an adhesive connecting the two?

    Love your site! Thank you all for sharing so much information!

    Reply
    • The silicone II is between the XPS and the metal (to minimize squeaks); it’s not necessary to have adhesive between the minicell and the XPS.

      Cheers!

      Reply
  10. Hi antoine,
    Getting back into my project after a busy work season. I am installing the floor,just minicell. I am looking at the stair edging and have 2 questions..one it say it is attached with screws..oh no we dont want holes..and how did you do the edging in the “garage” as we don’t want to cover the spare tire access.
    Thanks,
    Barbara Enjoy Mexico by the way..check out Barra de Navidad on the west coast..

    Reply
    • The stair edging is screwed into the plywood, not into the van’s metal floor 🙂

      In the garage, the floor stops before the bolt for the spare tire…

      Good luck 🙂
      Antoine

      Reply

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