Using cob inside a wood shed for thermal mass?

Hey folks,

I recently got some land that I will eventually live on. Being a student I have a fairly limited funds and I'm considering the different options for a small home that would be both efficient and cheap. I'll be working on it over the holidays and summers for the next 2 years, until my studies are done.

Being in France and having limited knowledge in construction, I don't think a "traditional" cob house is not an option for me. Building a structure and roof seems a bit out of reach and a hiring someone to do it for me would cost too much. The benefits of cob regarding thermal mass are not to be ignored though, hence my question. Where I am I can afford a wood shed, home depot kit sort of thing. To me it sounds like a good base to start from.

Would it be viable to add a insulating layer (hemp or whatever), followed by a layer of cob for thermal mass on the inside?

The result would be a shed from the outside (so no issues with building permits, neighbors complaining about aesthetics or whatever) and super efficient and creative look inside (sculpted cob is just wonderful). To me it seems like the cheapest and most efficient way to have a small house (20 square meters). That is not too hot in the summer and good a keeping the heat inside during winter.

Ideally I want a home as natural as possible, that requires very little fuel to heat. While the wood from a home depot shed is probably treated with not so eco friendly materials, it seems like the most easily available/cheap option to me.

I'm open to anything, even widely different from what mentioned above.

Looking forward to your input.

So I've found that those kits sheds are quite expensive for what you get.

If I had enough money for one of those, I certainly wouldn't buy one.

Instead, I'd pay a carpenter to erect the frame of a building for me. (Even if it's just the very same shed.) This way, it will be plumb, level, and square, which makes all of the following steps achievable.

When you have a good, accurate frame, putting on sheathing and siding is not too bad. Putting on roofing is really quite easy. Pre-hung door units (don't try buying just the slab, get the whole unit) are no problem. Windows, not bad. Plumbing and electric... were you even planning on having plumbing and electric?

In other words, I think you can get a vastly better structure by paying an expert for the frame and doing the rest from scratch.

That's a fair point. I'm going to see a carpenter in December, I'm mostly trying to consider the different options.
A shed kit would cost about 1200euro.

I hope the carpenter will be a cheaper option. Be it for knowing where the materials come from, having more of an input on design, and working locally.
I'll have to keep it frugal and improve gradually. As all my savings went into buying the land, it will depend on how much I can make with my night job. My goal is to build a 20m2 house over the summer, having only school holidays to do prep work on the land. It has to efficient enough for me to live in it in two years. The earlier I can live in it, the more work I can do on the land.

Being close to a village I'm yet to see the cost of having access to water. I'm waiting to hear back on that before considering pluming. There's a fountain nearby so for now I can live without it.
Same goes with electricity, If i can afford a small solar setup I will otherwise I have family nearby so it's not necessary.

Hopefully I'll be able to afford it all otherwise I'll just wing it with an old trailer until more money comes my way