All prices are in Australian Dollar (AUD)
I decided to use PolyIsocyanuate (PIR) sheets as my primary insulation source. These come in all different thicknesses, I chose 25mm as this worked out best with the cavity space in my ceiling and walls.
The PolyIso is laminated on each side with a reflective foil to reflect radiative heat like the sun. The medium is a closed cell foam, which means water can not be absorbed inside the membrane, making mould very hard to grow inside.
Part 1 – PIR Insulation Install
Part 2 – Floor Install
Part 3 – Earthwool Insulation Install (Still to be completed)
Note: I’m leaving some cavity spaces un-insulated until I have roughed in all the wiring, which I will be using Earthwool in those cavities. Once that is in I will amend this post and update it with the Earthwool insulation install.
Price – AU$860 for 12 sheets
I sourced the PIR foam from a company called Australian Reflective Insulation.
The insulation was installed underneath the ply subfloor, the ceiling and large wall cavities. I used Sika Spray adhesive to secure the insulation sheets to the walls, although I recommend finding something stronger as I did have some slight problems with its holding strength.
Part 1 – Insulation
I used the method of using timber lengths that act as a prop, with an offcut of fence paling in between the prop and insulation to increase the surface area of pressure on the insulation.
1. Measure up the length your prop needs to be, taking into account the thickness of your insulation and fence paling offcut. You could also use 40mm electrical conduit instead of timber as this bends and is more forgiving (but more expensive).
I would do the ceiling first, and then the walls as you can cut your props shorter once the ceiling is complete.
2. Cut your props to length.
3. Measure up the size of your insulation sheets.
4. Mark out and cut your sheets. A 1 meter straight edge came in handy, as well as a circular saw (although you can use a large stanley knife).
5. Spray the van surface with your adhesive spray, then spray your insulation sheet with the adhesive spray. Allow them to become tacky before proping them up. (As mentioned before I would recommend finding a stronger adhesive than the one i used).
6. I waited 24 hours then removed my props.
7. After about 2 days a few ceiling insulation sheets fell down. I believe this is because the roof is slightly curved and the insulation was trying to return to being flat. My adhesive alone wasn’t able to resist this force.
I resprayed the surfaces with adhesive, then screwed some fence paling lengths into the battens with small offcut packers to apply some hard pressure against the insulation. Once the final sheeting goes in, I will apply 3 packers per bay of insulation to ensure they can never move.
8. Now that the ceiling was done, I cut my props shorter so I can repeat the process for the walls. I used baking paper to make a stencil of the corner and cut them out using a stanley knife.
8. Now that all the insulation sheets were in, it was time to fill in all the gaps. I used Sika expanding foam to achieve this.
*Be aware that this stuff expands larger than you think it will. It is also really hard to get off skin so use gloves and your worst clothes. It is inevitable to spill some, wait till it dries completely before trying to remove from any surfaces.
9. Once you’ve filled all the gaps, let it dry for 24 hours then come back to shave everything off flush. Once the foam had set, the insulation felt rock hard in its place.
10. Check with a straight edge across your walls and ceiling that no insulation is protruding. In my case the back wall edges were protruding slightly which I shaved off with a hacksaw blade.
Part 2 – Floor
For the subfloor I used 17mm Structural Plywood sheets (1200mm x 2400mm). Below the plywood was a layer of the PIR 25mm insulation sheets. I sourced the plywood from Bunnings.
I used 8mm (M8) guage x 65mm long Stainless Steel countersunk bolts, with M10 washers and Nylock Nuts to secure the floor to the van.
*Warning – My carpenter friend told me that stainless and aluminium react together, and that there are special washers you can buy to keep the 2 dissimilar metals segregated. I had already bolted the floor when I found out.
*Tip 1 – There will most likely be a slight bend in your plywood sheets, so that if you layed it flat on the ground either the ends or center would not be perfectly flat. When laying your floor, make sure the bend is so that the ends touch the ground whilst the middle is raised.
This way when you secure your floor, the ends wont try to stick up, creating levelling issues (which is a small problem I ran into).
*Tip 2 – Also try and offset your insulation joins, to your plywood joins. Don’t cut your insulation sheets exactly the same as your plywood sheets, as all the joins will be in the same place. Offset them atleast by 100mm, this will deter any vertical movement in your floor when putting weight close to the joins.
I made all my pieces the same, although there isn’t enough vertical movement to cause problems.
Plywood cost – AU$270 for 4 sheets
1. Measure out your floor dimensions, I used a scrap copper pipe to make a template around the wheel arch.
2. Cut out your insulation and plywood, I measured so that the plywood wood meet center down the middle.
3. Lay the back of your floor down, insulation then plywood.
4. I used standard Sika Flex in between where all the ply meets each other and the metal walls to stop any squeaks.
5. Next I marked out on the ply where I want to put bolts, and roughly transferred these measurements to underneath the van to see if I would hit any chassis or other important things.
I then pre drilled the holes and secured the floor down with the bolts. I got a friend to hold a spanner underneath the van on the nut, while I screwed at the top with an impact driver.
6. I then repeated the process on the second half of the floor. (I allowed an overhang near the door for my kitchen).
7. (Optional) I had to plane down some of my floor near the joins just to get it perfectly level.
Congratulations! Now you’re floor is installed, the foundation of the whole van build!
Total Gear/Cost Breakdown
12 x PIRMax 25mm Insulation Sheets = $860
4 x 17mm Structural Ply Sheets = $270
5 x 500mL Sika Boom Expanding Foam = $65
5 x Sika Adhesive Spray = $70
Bolts/Nuts/Washers – $100
Pine Timber = $20
Total = $1385