Van Build: Floor Structure Beams

First things first are the cross beams... We got some roof beams (that are treated and for some reason are blue?)

Written By Freedom Strider

On January 18, 2020

Starting with the horizontals are the best since the van is over 4m long, and we organised them so that the beams will be under where our furniture is going, so we can secure them to the beams. It took hours of measuring and testing, although I must say a hand saw would have made it take at least 3x longer.


bubblewrap the wheel arches

Since we are putting down the floor, we have to put our moisture barrier over our wheel arches, otherwise, we’ll never be able to reach them after.

We measured and sliced up our Reflectix (bubblewrap covered in foil) and coated the wheel arches, securing it down with aluminium foil tape around all the edges to give a secure seal.

floor insulation - van conversion


plan your beam grid

Laying down your floor beams strategically is a wise thing to do, as it allows you to screw your furniture into your beams later on in your build. ✏️

Hence, knowing your layout at this point is a good idea… (although through the build it will probably change around a billion times so don’t worry too much about it).

We planned for 10 widthways beams, roughly evenly spaced, but with a greater concentration in high traffic/furniture areas.

floor beams structure - van conversion


We took care to not leave too large gaps between each widthways beam or the load bearing of the floor would have been uneven, which could result in squeeks, bendy floor, or even cracks.

floor beams structure - van conversion


the wood

We bought 25x38mm wooden battens because the PIR Insulation board we are installing is 25mm thick, so the beams and the board will be the same thickness and give an even floor.

floor beams structure - van conversion


measure and mark

By pre-planning your beam grid, you can buy the right number of beams and then measure and mark the wood to be cut with the least waste material at the end. 📏

We marked out our widthways beams first since we knew our pre-plan will have a noticeable margin of error, so we decided to do the lengthways cuts after the widthways beams have their final position confirmed. 

Cause you know, we’re bound to mess it up at some point, so just taking it slow. 😅

floor beams structure - van conversion


slice with power

Mitre Saw is by far the best investment for this job – it was only £50 well worth the purchase.

Not only does it cut true and straight, but it takes around 2 seconds to cut a beam.

A job that would have taken an hour by hand took us 5 minutes by mitre saw.

It was awesome! POWER! 💥


arange and adjust

After the widthways beams were cut, we arranged them in the van, and adjusted them so they fit.

Make sure to double check the 25mm side is the height of the beam (otherwise you’ll end up with a bumpy floor).

We then measured and cut the lengthways beams. These were dependent on the distance between the widthways ones, and took a lot of cuts but we got them all fitting snugly.

Remember to take into account the thickness  of the beams (in our case 38mm) when measuring the lengthways beams, otherwise you’ll end up with inconsistencies.

Best to do the measurements in the van with the widthways beams in place.

floor beams structure - van conversion
floor beams structure - van conversion


Our van floor wasn’t flat, it had natural bumps in it to dampen road noise. We positioned our blue beams to rest on top of these ridges so that it allows for airflow underneath the insulation (since the PIR board will also rest on top of these ridges). 

It also means that if you get a water leak (like we did) the water travels down the gaps to the back of your van, instead of creating a soggy moldy mess.


stick and secure

Once everything was cut, we stuck it down with Sikaflex EBT+ and put tiles on top to weigh the beams down so it could stick properly (the beams had a tendency to spring up, since y’know, it’s wood, and it’s winter). 

The Sikeflex EBT+ worked really well, it dried flexible allowing for the beams to flex as you’re driving but without coming loose. 💪

Some people screw their beams to the floor instead of sealant (or in conjunction), but any holes = more chance for rust, so we didn’t. The sealant is strong enough.

But by all means, screw them down if you wish, just waterproof and rust protect the holes really well (and try not to pierce anything really important underneath the van).

floor beams structure - van conversion
floor beams structure - van conversion


A 300ml tube should be enough for the whole floor – we were a bit over enthusiastic and ran out on the final beam.

We tested Pinkgrip but later found it to be rather weak and useless for this structural job, so we used another sikaflex sealant instead.

Use a good, flexible adhesive sealant, not a cheap one.

floor beams structure - van conversion
floor beams structure - van conversion
floor beams structure - van conversion
floor beams structure - van conversion


quick look

Quick Steps Overview:


  1. Plan beam locations
  2. Mark and cut widthways beams
  3. Mark and cut lengthways beams
  4. Adjust any lengths if needed
  5. Stick beams to floor