A 40x80 barndominium is 3,200 square feet, and the extra length over a 40x60 is usually dedicated to serious shop, storage, or equipment space rather than more bedrooms. This is the size for people who need a substantial workshop or want to park large vehicles indoors while still having a full home attached. As always, the building is a fraction of the total; land, site work, and the cost of conditioning that much space drive the all-in number, as covered in our cost guide.
With 80 feet of length, a 40x80 typically splits into a generous home on one end and a large open shop on the other. A frequent layout finishes 2,000 or so square feet as a three- or four-bedroom home and leaves the remaining 1,200 square feet as a tall, open work or storage bay.
What 3,200 square feet enables
- A full three- or four-bedroom home with room for an office
- A 40x30 or larger shop with space for vehicles and equipment
- A drive-through bay with overhead doors on both gable ends
- Indoor parking for an RV, boat, or trailer with a tall door
- A home, shop, and separate storage area all under one roof
The scale here changes how you think about the building. The shop side can function like a small commercial space, with room for lifts, large benches, or stored equipment, while the home side remains a complete, comfortable residence. The two are usually separated by an insulated wall to keep heating and cooling efficient.
Cost considerations at scale
A 40x80 shell is large, but the proportions hold: the kit is still a minority of the all-in cost. What changes is the impact of how much you finish, since conditioning and finishing 3,200 square feet is very different from finishing 2,000 and leaving the rest as open shop.
- Larger slab and shell than the mid sizes, priced accordingly
- Finished home area carries the highest per-square-foot cost
- Open shop area stays inexpensive when left unconditioned
- Tall doors and extra openings add to the shell cost
- Land, access, and site prep remain the dominant variables
Finish level and siting
The budget-to-high-end range on a 40x80 is the widest of the common sizes, because you might finish anywhere from half to all of the footprint. A practical build pairs a comfortable home with a bare working shop; a high-end build finishes the home to custom standards and insulates the shop too. Compare the shell using our kit price guide, then add your land and site costs to get a real total.
Frequently asked: 40x80 barndominiums
- How is a 40x80 barndominium usually laid out?
- Most people split it into a finished home of around 2,000 square feet on one end and a large open shop of roughly 1,200 square feet on the other. The two sides are separated by an insulated wall so the shop does not drive up heating and cooling costs.
- Can I park an RV inside a 40x80 barndominium?
- Yes, if you spec a tall overhead door and reserve a deep enough bay. The 80-foot length leaves ample room for an RV, boat, or trailer in the shop area while still housing a full home on the other end.
- Is a 40x80 overkill for just a home?
- For living space alone, 3,200 square feet is a lot, and finishing all of it raises the cost considerably. Most people choose a 40x80 specifically because they want a large shop or storage area attached, not because they need that much house.
- Why does finishing choice matter so much on a 40x80?
- Because the footprint is large, the gap between finishing all of it and leaving a big shop bay open is substantial. Finished living space costs far more per square foot than open shop, so your finish decision is the main driver of the all-in number.