Due to the huge amounts of rain we get here, I need to expedite certain aspects of this build. Especially the time during which my floor assembly resembles an empty swimming pool.

I decided to cut all the insulation to size at this stage because I don’t want the floor assembly in ‘swimming pool mode’ for any longer than it has to, just incase it rains.

So I measured the spacing between joists. If my framing had been 100% accurate, the spaces should have been 14 1/2” each, but there’s a little nudge room of an 1/8” or two here and there.

Cutting the Rigid EPS Foam

The video ‘selling’ this foam, boasts how clean and easy it is to cut. This unfortunately was not my experience. I’m guessing it’s mainly because I didn’t have the right kinda tools for the job.

A huge part of this build is about eco friendliness wherever possible and as an avid enviro I wanted to be as caring towards the environment as possible.

We have chosen sheep wool for the wall and ceiling insulation, yet I went with the least toxic rigid foam option for the floor, mainly as I am worried about damp in the floor and also to prevent rats and such from entering the floor system.

Such a Mess

As I began cutting the foam, I wished in some way, I had not chosen this product. The reason being that thousands, if not millions of little plastic particles fire off in all directions and it was breaking my heart.


I am adamant to never use disposable cups and I make such careful choices, for me to see this, was upsetting. But there was no turning back now, let’s just hope that the insulation does it’s job well.

As I chose 3” thick insulation, none of the saw blades would make it entirely through and this was one of the main issues. It took me longer to cut it and after trying the skill saw and the jigsaw, I realised the jigsaw was a better option as it created less mess.

The first few panels were cut shodily and are all rough around the edges. But after a few, I developed the best practice that I could manage with the tools I had.

After cutting through one side with the jigsaw, I would then grab a bread knife and reached through from the other side, at an angle, to cut the rest of the panel.

cutting EPS with Jigsaw

cutting EPS Tiny House

By lunch I had finished.

I layed out all the panels and marked them for their location, before stacking them away in the shed for the time that I need them.

EPS cut to size Tiny house

On to the Ply

After lunch, I moved onto the plywood.

I was very nervous about getting this right. The 1/4” marine grade ply, is just over $50 a sheet and after my time spent figuring out the layout, I’d realised that I SHOULD be able to just scrape by with the 5 panels. I have 6 just incase, but I’m always happy to return unused stuff for some credit.

I aligned the first panel, dry, as a test run and then scratched my chin for a while as I layed the second sheet next to it.

I was stalling a little, but eventually, just got on with it.

I used PL construction adhesive on the joists and then used 2” nails at 6” intervals along the edges and then 12” in the centres (known as ‘in the field’).

The first cut, on the second panel, went surprisingly well and gave me a huge boost of confidence. It was in-fact the first piece of plywood I’d ever cut in my life!

So from here on in, it was all about making the placements neat and tidy and cutting the right measurements around the wheel wells.

part done marine ply tiny house trailer

I was super happy that all the panels were lining up great with my 16” on centre joists.

16 on centre plywood panels

Due to the additional 1 1/2” length of the trailer, I had added a second 2 x 4 at the very back of the trailer, just inside of the rim joist, to give me a nailing surface for the plywood.

It was such a beautiful day and time flies on by when you’re having so much fun.

I had almost finished when I ran out of PL. I’m sure I could have finished without it, but I want to do it properly for the base.

As it’s ‘Good Friday’, all the stores were closed, so I cleaned up for the day and thought I’d finish her off properly tomorrow.

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What’s next?

I am still undecided about whether I am going to paint this plywood. Remembering that it is the underneath of the trailer, it might need some kind of weather proofing, but as I’m not planning on driving it around, I’m not sure how much protection it’s going to need?

Maybe some decisions will occur in my sleep.