40x60 Barndominium Floor Plans in Oklahoma
A 40x60 is the classic barndominium footprint: 2,400 square feet under one clear-span roof, wide enough for a double-loaded plan and long enough to split between a house and a shop. It holds a comfortable three- or four-bedroom home on its own, or a smaller house with a two- or three-bay shop at one end. In Oklahoma the 40-foot width also leaves room to add the things this climate asks for: a hardened room, a proper mudroom, and a deep porch along the long side.
What actually changes at this size
The dimensions are the easy part. These are the decisions that follow from them.
Clear span, no interior posts
A 40-foot clear-span steel or post-frame building needs no bearing walls inside, so the plan can be drawn freely and changed later. Interior walls are partitions; the bedroom wing, great room and shop can sit anywhere along the 60-foot length.
Septic sized by bedroom count
Oklahoma's on-site sewage rule, OAC 252:641, sizes an individual system at 200 gallons a day for up to two bedrooms plus 66 for each additional bedroom, with a tank of at least 1,000 gallons for four or fewer bedrooms. A 40x60 can hold four bedrooms, so settle the count before the DEQ soil test and Authorization to Construct.
A shop bay at one end
Split 40x60 into 40x40 living and a 40x20 shop, and the shop takes a single wide door for a truck and trailer. Under Oklahoma's amendments to the 2024 IRC, a garage needs a side-hinged egress door of its own; the wall to the house carries the model code's garage separation.
A porch along the 60-foot side
The state atlas published by the Oklahoma Geological Survey describes hot summers and persistent southerly winds. A 10- to 12-foot porch along the south-facing long side shades the main windows and adds 600 to 720 square feet of shaded outdoor living.
2,400 square feet is enough to put the shelter where you need it
At 40 by 60, a plan does not have to squeeze a storm shelter into leftover space. FEMA's guidance allows a safe room inside the building footprint and notes it offers the benefit of quicker access; its minimum for a residential tornado safe room is 3 square feet of usable floor per occupant. A central room at the junction of the bedroom hall and the kitchen, a pantry or laundry built as a hardened room with a labeled door, is reachable from every part of the house. Oklahoma does not require one. If you add one, the State's adopted code requires it to be built to ICC 500 with a 250 mph design wind speed, and FEMA notes a safe room built during construction costs less than retrofitting the same room later.
How people actually split 2,400 sq ft
Three common ways to divide this footprint. Yours does not have to match one exactly — this is a starting point for the conversation, not a catalog.
Four-bedroom family plan
2,400 sq ft living
Four bedrooms and two baths split either side of a central great room and kitchen, with the laundry and pantry safe room at the middle of the plan. The mudroom opens from the side entry.
House plus shop
1,600 sq ft living (40' x 40') / 800 sq ft shop (40' x 20')
A three-bedroom house at one end and a single deep bay shop at the other, joined through the mudroom and laundry. The shop keeps its wash water off the septic system.
Half and half
1,200 sq ft living / 1,200 sq ft shop
A two-bedroom house and a two-bay equipment shop under one roof. Suits a working property or a retirement plan with serious hobbies. The shelter can sit in the shop slab or inside the house; inside is quicker to reach.
Ways to build this size
A 40' x 60' footprint can go together several ways. These are the service lines most relevant to it.
Barndominium Kits
Barndominium kits for Oklahoma land: steel or pole barn shell packages sized to the wind, snow and frost values your own city or county uses.
Read moreShop Houses
Shop houses in Oklahoma: a working shop and a finished home under one roof, with room for trucks, trailers, tools and a storm shelter in the slab.
Read moreSteel Frame Homes
Steel frame homes in Oklahoma: red-iron barndominium frames with wide clear spans, bolted to a slab designed for the clay and wind on your land.
Read more40x60 Barndominium: common questions
6 questions worth settling before this plan is drawn. If yours is not on the list, put it in the survey.
How many bedrooms fit in a 40x60 barndominium?
Is a 40x60 all living space or house plus shop?
Where should the safe room go in a 40x60?
What septic system does a 40x60 need?
How big a porch fits a 40x60?
What should be decided first on a 40x60?
Want this drawn for your program and your parcel? That is where a build actually starts.
Sources
- FEMA — Frequently Asked Questions About Building Science (safe rooms)
- Oklahoma Uniform Building Code Commission — 2024 IRC permanent rule, OAC 748:20-6
- ICC — ICC 500-2020, ICC/NSSA Standard for the Design and Construction of Storm Shelters
- Oklahoma DEQ — OAC 252:641, Individual and Small Public On-Site Sewage Treatment Systems
- Oklahoma DEQ — Sewage Treatment
- ICC — 2024 International Residential Code, Chapter 3 Building Planning
- Oklahoma Geological Survey — Educational Publication 9 (2008), soil, vegetation and climate pages
Start your plans
Tell us what you want to build and we will draw a 40' x 60' building for your program, then confirm what it looks like on your parcel, which office permits it, and a realistic budget range. That conversation costs nothing.