40' x 60' · 2,400 sq ft footprint

40x60 Barndominium Floor Plans in Idaho

The 40x60 is the most requested barndominium footprint for a reason. At 2,400 square feet it holds a full three- or four-bedroom house, or a comfortable house and a real shop, under one simple roof. The 40-foot width is where a steel or pole frame's clear span pays off: no interior posts, so rooms can go anywhere and a shop bay stays open. In Idaho that 40-foot span is also carrying snow, and how much depends on where the building stands. A 40x60 plan that works in the Treasure Valley may need a heavier frame in a mountain valley, even with the same rooms inside.

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What actually changes at this size

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

Clear span, free floor plan

With no interior posts, a 40x60 can put the great room, kitchen and bedrooms anywhere, and move walls later without touching the structure. A shop end stays a single open bay. The trade is that the roof frames or trusses carry the whole 40 feet, and with it the site's snow, so the frame is specified for the address before the plan is final.

Roof pitch and where the snow goes

A steeper steel roof sheds snow sooner and in bigger slides; a lower one holds it longer. The University of Idaho report sends designers to the national loads standard for roof slope, unbalanced loads, drifting and sliding snow. On a 40x60, put entry doors and overhead doors on the gable ends where you can, and size any porch or lean-to below the eave for the snow that slides onto it.

If part of it is shop, the shared wall is heavier in Idaho

Idaho replaces the model code's dwelling-garage separation table. A shop or garage in one end of a 40x60 gets at least 5/8-inch Type X gypsum board or equivalent on the garage side of the wall and ceiling it shares with the house, and the house needs an egress path that does not run through the shop.

Bedrooms set the septic, not the footprint

A 40x60 can be a two-bedroom house with a big shop or a four-bedroom family home. Idaho's septic rules size the tank by bedrooms: 1,000 gallons for up to four, plus 250 for each one after. The public health district for your county evaluates the soils and issues the permit.

The span and the snow

The frame for a 40-foot span is sized for your site, not for the plan

Under the 2018 International Residential Code, which Idaho adopts with its own amendments, the local jurisdiction fills in the ground snow load for its area. The 2015 University of Idaho study computes the load from each site's elevation and urges users to verify it with the local authority having jurisdiction. Above a certain ground snow load the code's prescriptive framing chapters stop applying and the building must be designed for the load. For a clear-span 40x60, that is why the same floor plan can need a different frame, girts and roof panels at a different address.

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.

All living, four bedrooms

40' x 60' / 2,400 sq ft living / 4 bed, 2.5 bath

A split-bedroom plan with the primary suite at one end, three bedrooms at the other, a vaulted great room and kitchen in between, and a mud room and laundry at the side door. The entry sits on a gable end, clear of sliding snow.

Half house, half shop

40' x 60' / 1,200 sq ft living / 1,200 sq ft shop

A two-bedroom house at one end and a 40x30 shop at the other, with a tall door on the gable end. A mud room links the two; the house keeps its own exterior door.

House with a two-car garage

40' x 60' / 1,700 sq ft living / 700 sq ft garage

Three bedrooms, two baths, a great room and a two-car garage at one end behind Idaho's 5/8-inch Type X separation. A good fit where a separate equipment shop will follow.

Ways to build this size

A 40' x 60' footprint can go together several ways. These are the service lines most relevant to it.

Steel Construction

Steel and metal building construction in Idaho: red-iron frames and steel building kits for barndominiums, sized to your site's snow load.

Barndominium Kits

Barndominium kits for sale in Idaho: steel and pole barn shell kits sized to the snow load your building department sets, with honest help on kit prices.

Shouses

Shop houses in Idaho: a heated working shop and a home under one roof, planned around your zoning, snow load and the residential code.

40x60 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 bedrooms fit in a 40x60 barndominium?

As all living space, three or four bedrooms with two or two and a half baths is comfortable. Split with a shop, two bedrooms is typical. The clear span means the layout can change without moving any structure.

Can a 40x60 barndominium handle Idaho snow?

Yes, when the frame is sized for the site. The ground snow load varies with elevation across the state, and where your city or county runs a building program, its building official sets the figure for your site. Above the load the code's prescriptive framing tables cover, the structure must be designed for it, which is normal for a clear-span barndominium in snow country.

What roof pitch is best for a 40x60 in Idaho?

There is no single answer. A steeper pitch sheds snow more readily but sends bigger slides off the eave; a lower one holds snow longer and puts more of the load on the frame. Choose the pitch with the frame design for your site's snow load, and plan doors and lower roofs around where the snow will land.

How much of a 40x60 should be shop?

As much as your equipment needs. A 40x30 shop holds a truck and a tractor or a boat with room to work; an RV needs more depth and a taller door. Many owners start with more house and plan a separate shop later, or the reverse.

Is a 40x60 barndominium too big for a small acreage lot?

The building itself fits most parcels. What needs room is everything around it: the drainfield and its replacement area, the well and its separation from the drainfield, the drive and turnaround, and, on wooded land, the defensible space the Idaho Department of Lands recommends out to 100 feet.

Can I buy a 40x60 barndominium kit?

Yes. A 40x60 is one of the most common kit sizes. Make sure the kit's frame and roof panels are specified for the snow load at your address, not a generic figure, and that the package matches the permit set, where your city or county reviews one.

Keep reading

The pages that answer the next question this one raises.

Barndominium with shop floor plans

When the shop half grows: RV bays, equipment doors and how Idaho treats 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 figures on this page are from the 2018 International Residential Code as Idaho adopts and amends it (the Idaho Residential Code), and from Idaho's septic rules as read in September 2026. The code in force when your plans are reviewed governs. Snow load and frost depth are set locally, by the building official where your city or county runs a building program.

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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.

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