Floor Installation in a camper van

TLDR: Minicell foam spray glued between ribs, followed by Thinsulate, Minicell, smooth plywood, and finally sheet vinyl.

I’ve scoured the blogs, forums, and YouTube videos for a nice insulated, all season floor installation in a camper van conversion. Wow, there’s a lot of people doing different things. Fancy things like adding radiant flooring (actually pretty easy to add if you use click vinyl instead of sheet vinyl!) After a lot of debate and research, I decided the easiest approach would be a 4 layer approach of foam and thinsulate topped by 1/2-inch plywood and vinyl sheet flooring, with glue tacked ONLY between bare metal and the foam between the ribs. The rest of the layers float. The plywood has lapped edges. For the gaps between the walls and the flooring, we used caulk backer rod and silicone. No spray foam. Read ahead for how we did this, and why we didn’t go with more complicated flooring such as wood ribs or screwing in the flooring.

First off, the weight of the flooring materials was plenty enough that it was not going to move if it wasn’t screwed down. Second, the cabinets, shower, and bed installation is held mostly in place by the walls, not all by the flooring.

An important side note about insulation: I chat about our sheep’s wool insulation here, but I want to explain why we didn’t use it for the flooring. This closed cell foam will not grow mold and doesn’t hold onto water. When condensation is an issue – and if you run a heater in the cold or camp in extreme temperature differentials, it will be – condensation has shown up and dripped out of our van via the floor. If you use sheep’s wool in your flooring it can get wet! I’ve heard this can be very unpleasant. Just be warned! I’m now very glad we do not have sheep’s wool in our flooring.

Cutting, sealing, and glueing wood ribs to the metal ribs on the floor seemed extremely time consuming and overkill. There are plenty of full time van lifers who have floating floors with no problems. Unless you have specific engineering or load requirements, there’s no reason to do all that unnecessary work. Skip it and save both time and money.

Honestly, I didn’t want to build the floor at all. I really wanted to buy a kit, but there weren’t any for the 148 ext Transit cargo van at the time. Bummer. Now pre-built floors are available if it’s in your budget.

There’s 2 reasons we built over the passenger side step in the van:

1) It’s a nice shoe storage space
2) Easier to move my paraplegic husband in the van without a step

In our case, flat floor space was really the driver, with shoe storage being a side benefit.

The main reason I chose 1/2-inch plywood over 3/4-in plywood is because I can carry a piece of 1/2-inch 4’x8′ plywood by myself, and I cannot do that with 3/4″. 1/2″ is easier to lift and cut with a table saw or jigsaw, and easier to put on and take off my roof rack from the local hardware store. 1 year later with a full build on top of it, I have ZERO problems with it and I’m confident 1/2″ is perfectly fine and 3/4″ would have added uneccessary extra weight and headache.

This is the kit we used – specifically with the 3M TAI added, plus plywood and sheet vinyl from Home Depot. Since we plan to do winter camping and I’m very much into added sound insulation (more info here!), I wanted to add the TAI (Thinsulate Acoustic Audio) and go with the slightly thicker foam. A 3 season only camper could use thinner foam and go without the TAI, but I’m pretty happy with this flooring even if it’s mostly in the warmer months.

Tools and Materials

Tool/Material	Quantity	Description	Link to Buy
Flooring Kit	1	The closed cell foam and Thinsulate acoustic layers that make up the floor	https://ebay.us/MaI3DR
4′ x 8′ 1/2″ sanded plywood*	3	The “sub-floor” layer	Local hardware store
Jigsaw	1	To cut the wheel well shapes
Table saw OR router	1	To cut the lap joints
Sheet vinyl*	1	Cheap and easy to apply, and looks fabulous!
Vinyl Glue		To attach the sheet vinyl
Bond Enhancer*	1	Applied to the wood to increase bonding
Paint roller	1	To apply the vinyl glue to the plywood
Sewing scissors	1	To cut Thinsulate cleanly (these will cut like butter!)
Measuring tape	1	Measuring fill pieces, etc
Utility knife	1	Easiest way to cut the foam
Extra utility blades		Cuts are cleanest with fresh blades
Straight Edge	1	Guide for cutting clean foam lines
Titebond	1	Glueing the lap joints
Gorilla Glue Spray Adhesive	1	Glue down foam between joints
Rustoleum	1	Covering any rust
Large pieces of cardboard or newsprint	1	For making the flooring template
Packing Tape	1	Taping template pieces together
Contour Gauge*	1	Used to trace the wheel well and pillars
Foam backer rod	60 ft	To fill the gaps between the flooring and van metal
Silicone caulk	1	Holds the backer rod in place

The reason I went with the slightly more expensive sanded plywood is that is creates a perfectly smooth surface for either sealing with polyeurethane or applying sheet vinyl. I did NOT want to do the intense extra work of smoothing out sub-floor grade plywood. It’s really not worth the time vs price tradeoff here.

There’s cheap glue ($8) and specialty glue that may be recommended by the sheet vinyl manufacturer. I strongly recommended a higher quality glue (or the one recommended by the flooring manufacturer) that can be applied with a paint roller rather than a trowel. I ran out of the good stuff and tried the cheap stuff, and there was a HUGE difference in the way the vinyl applied. Cheap stuff was very difficult to press flat, even with a floor roller, and had bubbles that were very difficult to remove. Luckily this was in the rear of the van which was going to end up getting covered by benches and storage, so NBD. But the good stuff? The vinyl laid down so smoothly. Not one bubble. Easy and quick to press into place. Also, way faster and easier to apply with a paint roller than a trowel. Convinced yet? 🙂

Layer 1 of van flooring: Filling the rib gaps

1. Clean the floor of any dirt and debri. Sweep, vacuum, and wipe away any stuck stuff with a cleaner of your choice.
2. Cover any rust spots with Rustoleum and let dry.
3. Measure the lengths and widths of the gaps, and use the right angle straight edge to outline the cuts you need to make. This doesn’t have to be perfect, just close enough!
4. Score the foam (don’t cut completely through) with a utility knife and fresh blade using the straight edge as a guide for slicing. I like to rotate and/or replace the blade every 5 – 10 cuts. These dull pretty quick and will slow you down or begin to cause rough edges or tears. Once scored, cut fully through the foam at the edge, and then you can tear the foam cleanly down the scored line. Repeat for the other edges. Check out my video for some tips on how to accurately measure, and what I mean by scoring and tearing. 🙂
5. Spray both the foam and the floor (as per the spray glue instructions) and press the foam into place when tack tried (maybe 20 seconds or more, depending on your climate).
6. Repeat 3 + 4 until the entire floor is filled!

Layer 2: Cutting the template and thinsulate

I found using the Saker contour gauge really useful for getting decently accurate shapes for the wheel well and pillars. It took several Amazon boxes taped together to make a long template. I didn’t try to template the entire floor – only one side. The wheel wells mirror each other, the only difference is the step on the passenger side. The template should leave 1/4-1/2″ gap between floor and metal wall for movement and expansion.

Using the contour gauge is very easy – simply contour around the area, and then move and trace back onto the cardboard – don’t forget to leave a little gap!

I knew I wanted it flat over the step in the van – and I ended up filling it in with a box after creating the whole floor. If I could go back and re-do it, I would not cut out the shape of the step, and instead have the floor go over the step, and fill the supports in later. You can read about how I filled in the step with a shelf here!

The thinsulate will be pretty easy to cut and fit here, if you use sewing scissors – they will cut like a hot knife in butter and bring you joy. The TAI is a bit delicate so don’t pull hard or it will tear. I placed the sheet over the floor and used the template to cut to fit.

Layer 3: Foam

This is pretty easy to cut with our template! There is no glue involved and we’ll just lay it out and cut to fit. Don’t worry about it laying just loose – it won’t budge once the plywood is on top of it.

Layer 4: Plywood

I used 3 sheets of 1/2″ 4’x8′ plywood. 3/4″ isn’t really unneccessary and just adds extra weight, and it’s been holding up beautifully. Offsetting where the long edges meet makes it easier to cut lap joints and a little sturdier IMO. Once again I used the template and a jigsaw to cut out the wheel wells and pillars, and used a table saw to trim the wood to length. Remember to allow for the 1/4-1/2″ gap to the wall, and don’t forget to tape your edges before cutting! This makes the difference between an amateur and “professional” DIY build 🙂

After tracing the template, I tested with scraps to get the table saw blade to the correct depth of 1/4″. Then I ran the plywood through twice, slightly offset, to get the width of lap joint I wanted. This could have also been done with a router just as easily (perhaps easier?). The joints aren’t perfect but they are close, and I used a generous amount of Titebond III to glue them together. Also, I used a little bit of some wood filler for some of the larger gaps.

I also added a little wood filler to some othe junctions to smooth them out so the vinyl would go over it easier. I’m not an expert craftsman here when it came to creating lap joints – this was my first time trying to do such a thing. Still, a year and a whole build later – it’s perfectly fine!

At this point the floor is usable! I first put a large rug on it to keep it clean until my vinyl flooring came. I’m a HUGE fan of actively using your van WHILE you build it! It will teach you so much!

Layer 5: Sheet vinyl

There were 4 steps I took for sheet vinyl: Bond prep, apply glue, cut sheet vinyl to size, put into place! When I cut the template I tried cutting it exactly to fit – I don’t recommend this! Instead, cut the sheet vinyl a little bit larger to give yourself room to trim it once it’s laid down. As soon as the vinyl is laid onto the glue, it will be extremely difficult to move! The edge gaps in some places are a little bit larger than I would like, and if I could do it again I would make it a little larger and then trim the edges. Still, not the end of the world as the edges generally get covered by your build. I did not find a floor roller to be useful – just elbow grease worked (where I used the good glue!)

Finishing touch: Filling in the gaps

The final step in our camper van floor installation is to use foam backer rod and silicone caulk to fill in the edges. This is a very quick and easy step that is not very messy (unlike spray foam!). Just stuff backer rod into your gaps, doubling up if needed. After that genersouly apply silicone caulk to set and fill the remaining air pockets. Now you’re good to go!