30' x 40' · 1,200 sq ft footprint

30x40 Barndominium Floor Plans in Wisconsin

A 30x40 gives 1,200 square feet under a 30-foot clear span: enough for a comfortable two-bedroom house, a lake or hunting cabin with a loft, or a garage with living quarters as the first building on new land. It is a compact shell with a short perimeter, 140 feet of footing taken to the depth the Uniform Dwelling Code sets, and a roof designed for the county's snow zone. In Wisconsin the 30x40 is often paired with a loft under a steep roof or a basement below, because both add living space without adding footprint.

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What actually changes at this size

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

140 feet of frost-depth footing

A 30x40 has 140 feet of perimeter, and under the Uniform Dwelling Code its footings go below the frost line or at least 48 inches below adjacent grade, whichever is deeper (SPS 321.16). Keeping the rectangle simple, with no bump-outs, keeps that number and the cost down.

A 30-foot span in your snow zone

The Uniform Dwelling Code designs roofs for 40 psf in the northern zone and 30 psf in the southern zone of its snow load map (SPS 321.02). A 30-foot span handles either comfortably with standard post-frame trusses or a steel frame; the zone mainly sets truss design and spacing.

Loft or basement for more room

A loft over one end adds 300 to 500 square feet under a steep roof. A basement adds up to another 1,200. The loft is cheaper; the basement adds more and holds the furnace, water heater and well tank out of a small main floor.

The entry decides the layout

In 1,200 square feet the mudroom has to be efficient: a gable-end entry with a bench, hooks and a closet, and the laundry beside it if there is no basement. Keep the entry off the eave side, where snow slides off the roof.

Small shell, more space

1,200 square feet on the ground, up to twice that with a loft or a basement

The Uniform Dwelling Code fixes the two costly parts of any 30x40: footings below the frost penetration level or at least 48 inches below adjacent grade, whichever is deeper (SPS 321.16), around 140 feet of perimeter, and a roof designed for the snow load on the code's zone map, 40 pounds per square foot in the northern zone and 30 in the southern (SPS 321.02). Once those are paid for, the cheapest extra space is inside the shell. A steep roof over a 30-foot span leaves room for a loft over part of the floor; a basement takes the four-foot foundation wall the rest of the way down and adds another 1,200 square feet for bedrooms, storage and the mechanical room. Either one turns a cabin-sized footprint into a family-sized house.

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 house

1,200 sq ft on one level

Two bedrooms and a bath at one end, an open kitchen and living room at the other, a mudroom and laundry at the gable-end entry. A practical retirement house or starter home on rural land.

Hunting or lake cabin with a loft

1,200 sq ft main floor / 400 sq ft sleeping loft

One bedroom and a bath on the main floor, an open living area around a wood stove, and a bunk loft for guests or the hunting party. Built for weekends through the year and for the deer season.

Garage with living quarters

600 sq ft garage / 600 sq ft apartment

Half garage, half one-bedroom apartment, as the first building on new land while a larger house is planned. Before building, check how the local zoning ordinance treats living quarters in a building that may later become an accessory structure.

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 for Wisconsin land: steel or post-frame shell packages sized for your snow zone and frost depth, with a set ready for plan review.

Pole Barn Homes

Pole barn homes in Wisconsin built as real houses: post-frame posts below frost, trusses sized for your snow zone, and walls built for heating season.

Custom Plans

Custom barndominium floor plans for your Wisconsin parcel: drawn around the lake setback, the septic site, the slope and the plan review ahead.

30x40 Barndominium: common questions

7 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 bedrooms fit in a 30x40 barndominium?

Two comfortably on one level, with one bath and an open living area. Three is possible with smaller rooms. Adding a loft or a basement makes room for a third bedroom without enlarging the footprint.

Is a 30x40 big enough to live in full time?

For one or two people, yes. At 1,200 square feet it is the size of many small ranch houses. Couples who downsize into a 30x40 often add a basement or a separate garage so storage does not crowd the living space.

Does a 30x40 need interior posts?

No. A 30-foot clear span is well within standard post-frame trusses and steel frames, including under the Uniform Dwelling Code's northern snow zone of 40 psf (SPS 321.02). The walls inside can go anywhere.

Can I start with a 30x40 garage apartment and build a house later?

Often, but check the zoning first. The Uniform Dwelling Code says it does not affect local land use or zoning requirements (SPS 320.02(2)(b)), so whether you can live in the building before a main house exists, and what it becomes afterwards, is decided by your town, village, city or county zoning ordinance.

Is a 30x40 a good cabin size?

It is a popular one. It fits a bedroom, a bath, a living area around a wood stove and a loft for guests, on a footprint small enough for a wooded lot. On a lake lot, read the shoreland rules first. Land within 1,000 feet of a lake or 300 feet of a river in a town is under county shoreland zoning, and the state minimum setback for a new building is 75 feet from the ordinary high-water mark (Wis. Stat. 59.692; NR 115.05).

Who issues the permit?

For a dwelling, the body that enforces the Uniform Dwelling Code for your parcel: the city, village or town, the county where the municipality has not enacted its own ordinance, or a State-contracted inspection agency where neither enforces (SPS 320.06). The Wisconsin uniform building permit comes before any excavation (SPS 320.08).

How do I start?

Start the survey with your county, whether the 30x40 will be a full-time house or a cabin, and whether you want a loft or a basement. That sets the shell and the layout inside it.

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

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Sources

Start your plans

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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