Sorry I am late to the party, but I thought I'd add a little to the conversation as I have been considering doing just this.
I have been a part of 2 building builds a few years ago well before I started using CA (Chief Architect). I have been using CA for the last 6 months and have done numerous remodels, additions, and full house builds.
The way I have seen barndominium's built is to mount the windows in to the C-Purlin. This gives a 6" deep wall and the remainder of the window sill is just exposed C-Purlin. We have also finished a few areas of the building stubbed out with partial board for flush walls to put work benches against and the such.
In reality, we took a skill saw and just cut a groove in the top of the 2x4 so it would fit flush with the face of the Purlin. We turned the 2x4 on their face, so you have a 3.5" wide target behind the wall board, since we dont need it for any real structure outside of holding up the wall board. At the bottom/sill we welded angle iron in to give the bottom of the 2x4 a foot. Then we pre drilled and counter sunk self tapping metal screws to just hold the 2x4 in place. Same at top predrilled the c-purlin and ran one drywall screw to hold in place. Then screwed the partial board to that. This was to create a flush wall in front of the c-purlins to give a flat back for tool boxes and work benches.
I only mention this because this could be done to create a false wall inside the c-purlin for building the "house" walls. Fill with insulation (6" thick is at lot of insulation) for a house.
Ok, so back to building in Chief Architect.
I WOULD NOT build these two structures together. I'd do two plan files.
One with the house and one with the barn.
There are a few things that you would build out as needed. Say you need Dormers in a second floor windows. I'd just build those as expected.
The House would have a "roof" on that would match the underside of the I-Beam inside the building based on measurements.
There would be no shingles, but you would want insulation, so it would be easiest to just wall off the sections up to the beams, or even put decking on (but not needed).
You would only need to build out the dormers and such to meet the roof, and then finish those out on the metal building.
For rendering, I'd render the entire house, without the metal building.
You could do a "flat roof" and just deck the rafters, or leave it open and blow in insulation. I want to do a two story inside, with 2 bedrooms/1full bath up stairs, with dormers and windows on the end wall. The metal building might be higher than the finished height of the 2nd floor, and I'd just finish the rafters flat for storage on top if needed.
The windows would be deep sills 6-6.5" due to the c-purlins and molding.
I'd run all plumbing along the back wall in the design (meaning the wall that is exposed into the barn.) that wall would be covered in probably corrugated metal, which could be removed if needed, but insulated also.)
Yes I'd insulate the entire structure inside the building, because in Austin I see it getting up to 98 in the building often.
I'd insulate the roof of the barn like they do in metal buildings (minimal but still helps)
I'd have an air gap between the structure and the metal building roof, whether flat or at the same angle the metal roof building is at for the thermal separation.
Also on the Barn/Metal Building, always put 3 doors (large doors not man doors). Learned this from a pole barn forum years ago. With three doors, there is no situation you cant open a combination of doors and pull a draft, to evac the heat.
Other items I have learned across all the shops and such I have had, built, or friends have had:
The Man Door (standard entry door for the metal building) make it a 4.0! You can carry most anything in a 4.0 door without turning sideways or banging your elbows.
The "house" should have a front door/man door. The metal building should have a separate man door (4.0)
Put 14' garage doors, so you can drive any legal height vehicle, RV, bus, truck. You can get residential style doors for this height also.
Dog ear the door if you want to save space and have it closet to the exterior wall (dog ear at 12-13 feet, center height at 14')
Insulate the doors
Get openers with internet capability. Its easier to open on your phone than walk across the 60 foot shop.
Shop 3rd door can be a roll up, does not need to be as tall, but make it at least 9'x9', or 10' high
Make it where you can "drive through". Make the house only half the width if possible, and drive "behind the house"
Garage Doors you want to put at minimum of 30" from the outer wall. This works for the 14ft with a dog ear, and you have enough room for shelving and work benches.
I personally would put a workbench along the 60 ft run, and have 'stations' for drill press, grinder, vice/anvil, press, etc.
Break up the work bench with shelving (metal from Lowes works great and holds 1000's of pounds) then between the works stations you have storage for items for those devices.
Welders and tools are rolling carts so you can move them to the project.
A huge tool stack is nice, but I'd rather have a harbor freight $100 rolling tool cart, with $200 in tools, and have 4 of these over a huge tool stack that cost $3000, then you can just roll it to the project.
Car stacker for storage if you need it.
2 post lift for working on vehicles.
Center Ridge I-Beam should be free and clear to run a 3 ton rolling hoist the 60 ft length of the building
Wire the ceiling of the building with plug boxes on 2 circuits, 4 gang. Then hang shop lights.
3 way switch for light circuits (2 circuits each side of building, 2 switches each side)
This way you can turn on half the lights on each side independently. Every other light is the other circuit
This lets you put on 25%, 50%, 75%, 100% on 4 switches (3 way switches so 8 total)
For a 40x60, we found a 200,000 BTU Modine heater will make it hot enough to run you out in Texas' coldest weather.
Hand this inside the metal building regardless of the house.
Heat the entire building in the winter.
Natural Gas is better, but Propane is still effective enough to keep the shop at 65 degrees in 20-30 degrees outside.
Makes it easier to heat the "House" inside of it.
Collect rainwater from the gutters off the roof
We built our own, with a bird poop soup dump as calculated from information on the interwebs.
Then funnel to 4 x 2500 gallon tanks
5 micron, 50 micron and a UV filter to kill bacteria rated at 50 gallons a minute
Best ice for cocktails you have ever seen
As for the House details, I have yet to work out a plan, but here is what I am thinking.
3/2.5
Living, Master, Kitchen Downstairs
Master with onsite bath
1/2 bath connects to living, with pass through to shop (easy access from shop and living room) possibly under stairs
2 bedrooms up stairs, jack and jill full bath, dormer windows, end wall windows. hall to access both rooms (haven't worked all of that out)
I'd do some sound damping or double walls on the shop side
The slab would be shared for the entire building (possibly more footing/beams) in the area for the "house"
That is my approach, and I am going to start on some designs in the next few weeks since I have a lighter design work load right now.
But that should give you some real good nuggets to build a building that would exceed the expectations of most any hard core man cave dweller.
