I'm confused - are you building something inside the steel building or just creating living space within it? If the latter, this can certainly be done; I have a brother who lives in just such a space and it is beautiful inside while being low profile from the outside.

 

It won't look different than any other steel building with maybe more windows.

All insulation would be on the inside building.
I just sounds like a mobile home parked in a pole barn to me.

 

What would stop the steel structure from being a virtual oven?

 

From your description, I read you have a fully enclosed, basic steel shed (albeit with some glass roll-ups). Inside, is a completely detached "tiny house." So a 32'x24' shed allows an interior 30'x12'-ish footprint with a 30'x10'-ish parking space, depending on how much clearance you need to get at the exterior of the tiny house or the structure of the shed.

My first thoughts are you shouldn't treat is as an enclosed steel building with a separate box inside. It might be better to approach it as one building with a kind of an "exoskeleton" on 3 sides, because:
- Your living spaces need light and ventilation that can't go through another building.
- You have exhaust/fresh air, lineset for the a/c, vents, etc. that will need to "cross" the gap over to the exterior. Can be hidden, but will require some thought.
- I could see the local building dept pushing for the shed to be sprinklered having a separate enclosed structure inside.
- Is there a Lake Association that might have some design standards?

Here are some interweb pics. The one is a literal interpretation just for kicks.

 

Although less of a weather factor, you still would want air movements across the house and make sure indoor air is maintained well. Also if the barn is for machines, just the smell of gas or such would be unbearable. Even the smells of hay, dust and age add up. It seems mixing the two would make you install fairly large ventilation fans or such that use a lot of energy.
A house with a large overhanging roof and double deck roof that's insulated inside but has at least 2" space in between, would seem to be better choice and more connected to the world.

 

Will this mini-house be able to be separated from the mothership? In other words, do you plan to take it on the road?

Why do you want to do this? it does sound intriguing.

Like others have mentioned, you are going to have to insulate the steel structure or suffer the wrath of the Texas Sun.

As @carpdad implied, don't store anything using any kind of fuel inside the structure. You will need to vent it out and have a sprinkler system.

Personally, I would have a sprinkler system anyways. Be safe, not sorry.
I like the pictures that @3onthetree put up. Do they match what you intend to do?

 

Thanks for your replies. What I've found out is that this is essentially called a barndaminium and the house within a house is nothing more than the build-out. I'm not really looking to build a full house inside, just rooms and a loft. That's what a barndominium is.

One good feedback was that windows inside the build out need to be planned.

Thanks for your responses

 

Thanks for your replies. What I've found out is that this is essentially called a barndaminium and the house within a house is nothing more than the build-out. I'm not really looking to build a full house inside, just rooms and a loft. That's what a barndominium is.

One good feedback was that windows inside the build out need to be planned.

Thanks for your responses

So why not just build the living part as part of the bigger building.

 

Thanks for the pictures. The picture of the house inside the steel house is perfect. Now what we build in the inside wouldn't be quite so house-like and cute. Just an interior wall and loft but the raw steel part of it is close to what we have in mind. And I like the look a lot. They have the exact same garage doors we have in mind. I appreciate the picture.

 

A barndominium is just a marketing word for building out the interior of a steel building, keeping the exterior look of the massing and materials. At that point the "barn" walls are just cladding, and cost savings might not be realized with a steel kit over conventional house framing. If there is a function or aesthetic you're after, that can be accomplished in many ways.

For an independent structure inside another, the biggest issues are the light+vent and fire separation. It might be good to have a meeting with the building dept and assessors office (the entire structure may be taxed as occupiable rather than discounting the vehicular storage) first.

 

Maybe.

https://www.pinterest.com/pin/160792649172744154/