Building a barn, looking for ideas and advice…

We have plenty of roundwood on our land, and also some corrugated steel roofing. There’s also a few bits of dimensional lumber about the place that we can use for bracing and other stuff if we need to. I don’t have much building experience and have lots of questions to ask about building a small homestead barn with an earth/deep litter floor…

My ideas:
I don’t have to have any dealings with the government if I build a structure that is less than 258 square feet in footprint. To make anything up to 860 square feet I think just means I have to notify them that I’ve built it, but doesn’t require asking for permission.

I am leaning towards keeping it at that 258 square feet limit, because I imagine a larger structure would be more complicated and expensive to build. On the other hand I also want to make something that will suit future needs as well as current needs, so I am open to building a larger structure if I will get more use out of it. The spot I’d like to build it on is a flat-ish bit of land, only around 13 feet wide before it starts getting steep again, so it has to be rectangular.

My needs now are for six does, a buck, their kids, and a hayloft for storing tree hay and other feed. I also need to provide a yard for them attached to the barn, so that I can keep them there when they’re due to kid, or any other time that I don’t want them free ranging. I also might want to use this yard and barn as a spot to put cows and sheep once I set up rotational grazing, just so they have a spot to stay if the soil needs to be rested in the rotational paddocks.

We are on the warmer side of zone 8 or the colder side of zone 9, and only really need a barn to keep the rain and wind off the animals.

My questions:
Are there any ideal barn and barnyard sizes for around 7 goats, 1 or 2 cows, and maybe 7 sheep? It would only be in full-time use during kidding season for goats at the moment, and as sometimes shelter for the other animals later on.

Is it easy to keep cows, sheep, and goats all together at night in the same barn? Are there any considerations I need to make for housing different animals in the same space?

Everything except the bracing in my two ideas below are both roundwood (the bracing could be as well though) - what width roundwood would be best? It would probably be eucalyptus.

If a structure is around 19 feet by 13 feet, and I want to support a small hayloft on a second level, is the amount of bracing on my first sketch enough for this? On the cruck frame one, how many crucks would I need for 19 feet? I will be doing a kid stall in there somewhere, so I can easily add upright support poles for that bit and anywhere else it's needed. We have plenty of wood, and would probably prefer to do more crucks/supports of smaller width rather than less supports using thicker wood.

What do I need to know about foundations for this structure? Can I just dig a hole, put the roundwood in, and that is enough? I have free gravel I can use, and also stones and sandstone blocks as well.

In the roundwood book I got from the library he uses big square stones below ground, and just rests the cruck frame on those aboveground. I don’t have huge bits of stone, but plenty of smaller bits - could I make foundation pads out of smaller bits of stone stacked up underground a bit like a stone wall?

Do I need to do a french drain above the barn? It’s on a slight slope, so there’s a bit of drainage already.

If I build a hayloft for crawling/sitting room only, am I going to get annoyed with that later on?

For a beginner, would the cruck frame one, or the shed roof, the the easier and more failproof one to build?

Is there anything else you can think of that might be a good idea for me to consider with this project? Or any good links, books, or videos to recommend? Homestead barn building experiences to share?

Here are my ideas (each one somewhere around 10 to 13 feet wide):

If you need a minimal of space, have limited building skills, and very little money, a great barn to build would be an earth barn. When I do my classes on sheep farming, I actually bring in a model and make one of these barns because they are so fast, cheap and easy to build.

All you have to do is rent an excavator and make two piles of soil 7 feet high on one side, and 10 feet high on the other, set 16 feet apart at the top, packing the earth down as you go. Where I live, I can rent one for $300 per day, and in 8 hours or less, I could make the two required piles of earth.

Then cut two long poles to put on top of each pile lengthways, leveling them.

Then across the top start laying round logs side by side. Spike them into the lengthways logs. Just make sure the logs are big enough in diamter to hold weight, then cover with plastic, and add some soil to pold it down.

You want to make sure the floor of the earth barn is compacted, and that drainage is adequate so that water does not flow into the barn making a mess. But this will give you a earth barn of through-barn design making ventilation adequate, and clean out easy.

That sounds like a good design, similar to something I saw in Sepp Holzer's Permaculture. Is there any way to put a hayloft on one? I am getting a bit tired of being swarmed by animals at feeding time and need somewhere to store stuff as well.