A compact 30x40 barndominium sized like a starter home or cabin, with a covered entry porch, no large shop bay, and pines and birches at the edge of the yard.
30' x 40' · 1,200 sq ft footprint

30x40 Barndominium Floor Plans in Minnesota

A 30 by 40 foot barndominium gives 1,200 square feet on one floor: room for two bedrooms comfortably, or three with tight planning, plus an open kitchen and living room. It is a common first house on rural land, a retirement plan, or the house that goes up before a larger shop. The 30-foot span is easy for a steel frame or pole barn trusses, and the footprint is small enough that the foundation, the entry and the mechanical space take a larger share of the plan than they do in a big house.

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What actually changes at this size

The dimensions are the easy part. These are the decisions that follow from them.

The smallest septic tank still applies

Under Minnesota Rules part 7080.1930, any dwelling with three bedrooms or fewer needs a septic tank of at least 1,000 gallons, and 50 percent more with a garbage disposal. A 30x40 house is right at that line, so a third bedroom does not change the tank size, but a fourth would.

Radon control under the slab

Minnesota Rules parts 1303.2400 to 1303.2402 require passive radon control in new dwellings built with a slab on grade or a basement slab: a gas-permeable layer, a sealed membrane over the entire floor area with laps of at least 12 inches, perforated pipe under it, and a vent pipe up through the house. In a 1,200 square foot plan, the vent pipe's route through a closet or chase is planned with the room layout.

The entry takes space you should give it

In 1,200 square feet it is tempting to open the front door straight into the living room. The 30x40 plans we draw keep a mudroom or vestibule at the everyday entry with the laundry beside it, because in a Minnesota winter that is where snow, boots and coats stay out of the house.

Too big for the tiny-house rules, right for a small house

At 1,200 square feet a 30x40 is well above the 400 square foot line where Appendix Q of the Minnesota Residential Code applies, so it follows the full code: 7-foot ceilings in habitable rooms, bathrooms and laundry under Minnesota Rules part 1309.0305, an escape opening in every bedroom, and stairs to code if there is a loft.

A compact 30x40 barndominium sized like a starter home or cabin, with a covered entry porch, no large shop bay, and pines and birches at the edge of the yard.
Slab or frost wall

Your soil decides whether a slab on grade is allowed

Minnesota Rules part 1303.1600 permits slab-on-grade construction, designed to carry all applied loads, where the soil, natural or fill, is sand or pit-run sand and gravel to the county's minimum footing depth: five feet in Zone I counties and 3-1/2 feet in Zone II. On clay or silt, the footings go down to frost depth on a frost wall, or a soils professional determines otherwise. For a 30x40, that choice can be the biggest single swing in the foundation budget, which is why the soils are looked at before the plan is finished.

How people actually split 1,200 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.

Two-bedroom with a mudroom

1,200 sq ft / 2 bed, 2 bath

Primary suite at one end with its own bath, a second bedroom and bath at the other, an open great room and kitchen in the middle, and a mudroom with laundry at the side entry.

Three-bedroom compact

1,200 sq ft / 3 bed, 1.5 bath

Three bedrooms on one side of a central hall with a full bath and a half bath, and the kitchen and living room along the other long wall. Each bedroom gets its escape window on an exterior wall.

One-bedroom with a garage bay

800 sq ft living / 400 sq ft garage bay

A one-bedroom home with a single garage bay at one gable end under the same roof, entered through the mudroom. The common wall carries the garage separation required by the Minnesota Residential Code.

Ways to build this size

A 30' x 40' footprint can go together several ways. These are the service lines most relevant to it.

Barndominium Kits

Barndominium kits and shell kits for Minnesota land, sized to your county's state-set snow load and frost depth, with the drawings your permit needs.

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Pole Barn Homes

Pole barn homes in Minnesota: pole barn house kits and plans sized to your county's snow load, with posts and footings set below the state frost depth.

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Custom Plans

Custom barndominium plans drawn for Minnesota: your layout and shop, your county's snow load and frost depth, and a set ready for plan review.

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30x40 Barndominium: common questions

6 questions worth settling before this plan is drawn. If yours is not on the list, put it in the survey.

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How many square feet is a 30x40 barndominium?
1,200 square feet on one floor. A loft over part of it can add a few hundred more.
How many bedrooms fit in a 30x40?
Two comfortably, three with a compact layout. Each bedroom needs an emergency escape and rescue opening under Minnesota Rules part 1309.0310.
Can a 30x40 barndominium sit on a slab?
Where the soil is sand or pit-run sand and gravel to the county's frost footing depth, Minnesota Rules part 1303.1600 permits a slab on grade designed for the loads. On other soils, footings go to frost depth unless a soils professional determines otherwise.
What septic tank does a 30x40 need?
With three bedrooms or fewer, at least 1,000 gallons under Minnesota Rules part 7080.1930, or 1,500 gallons with a garbage disposal. The tank sits at least 10 feet from the house under part 7080.2150.
Is a 30x40 a good kit size?
Yes. A 30-foot clear span is simple for both steel and pole barn framing, and a kit that size is often ordered first, with a shop added later.
Could a 30x40 be a guest cottage on a lake lot?
Not under the state shoreland guest cottage standard, which caps a guest cottage at 700 square feet of land surface in Minnesota Rules part 6120.3300. A 30x40 would be the principal house on its own lot.

Keep reading

The pages that answer the next question this one raises.

Small barndominium floor plans

Smaller still: tiny-house cabins and one-bedroom plans for a Minnesota lot.

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40x60 barndominium floor plans

Double the footprint, with room to add a heated shop.

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Want this drawn for your program and your parcel? That is where a build actually starts.

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Sources

Code references on this page are to the 2020 Minnesota State Building Code, in effect since March 31, 2020, and to Minnesota Rules as published by the Revisor of Statutes. The code applies statewide, but whether a building permit is issued and inspected where you build depends on whether your city, township or county enforces it. The edition your permit is reviewed under governs.

  1. Minn. R. 1303.1600, Footing Depth for Frost Protection
  2. Minn. R. 7080.1930, Septic Tank Capacity
  3. Minn. R. 7080.2150, Final Treatment and Dispersal (setbacks, Table VII)
  4. Minn. R. 1303.2400, Radon Control, Purpose and Scope
  5. Minn. R. 1303.2402, Requirements for Passive Radon Control Systems
  6. Minn. R. 1309.0305, Section R305 Ceiling Height
  7. Minn. R. 1309.0310, Section R310 Emergency Escape and Rescue Openings
  8. Minn. R. 6120.3300, Shoreland Zoning Provisions

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Tell us what you want to build and we will draw a 30' x 40' 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.

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