Modern Barndominium Floor Plans in Washington State

A modern barndominium trades the farmhouse porch and board-and-batten for clean lines: a simple steel shell, big panes of glass, a low-slope or single-slope roof, dark metal siding and an open plan. In Washington that look runs into three practical questions before it is drawn. How much glass the energy code will carry, how the walls and windows stay dry through a western Washington winter without the deep eaves a farmhouse would have, and how a steel building's framing and slab handle condensation. None of them rule the style out; they decide how it is detailed.

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What actually changes with this feature

The look is the easy part. These are the decisions that follow from it.

Daylight is a floor, not a ceiling

Washington's residential code, WAC 51-51-0303, requires habitable rooms to have glazing of at least 8 percent of the room's floor area, unless artificial light gives an average of 6 footcandles at 30 inches above the floor. A modern plan clears that easily; the design question is how far past it to go, and which walls get the glass.

West of the Cascades, draw the overhang back in

A crisp modern roof with no eaves looks sharp in a rendering and wet in November. On the west side, a low-slope or shed roof still earns an overhang or a projecting canopy over every door and the biggest windows, and a single-slope roof should drain to the side away from the entry. The steel siding sheds water well; the window heads and the base of the wall are where detailing matters.

Keep the ground and the slab dry

Washington amends the residential code's under-floor rules: WAC 51-51-0408 requires a ground cover of six-mil black polyethylene over the soil in a vented crawl space, lapped at the joints and run to the foundation wall. On a slab, a vapor retarder and a drained perimeter do the same job. In a steel building, cold metal against warm, damp indoor air is where condensation starts, so the insulation and air barrier must be continuous at the girts and purlins.

East of the Cascades, dark metal and wildfire

On the dry side, dark siding and a lot of west-facing glass heat the house in August, so orient the glass north and south where the site allows, and shade the west wall. Metal siding and a steel roof are noncombustible, which suits wildfire country, but vents, soffits, decks and whatever sits against the wall still matter. Washington has no statewide wildfire building code in force, but some counties and cities adopt their own wildland-urban interface rules, so ask the building department what applies to the parcel.

Glass is the design, and the energy code counts it

Big windows are allowed; they are paid for elsewhere in the envelope

Washington's residential energy code, chapter 51-11R WAC, sets a prescriptive window U-factor of U-0.30 alongside R-60 ceilings and R-20+5 or R-13+10 wood-frame walls. On top of those minimums every new house must earn additional efficiency credits: 5.0 for a small dwelling, 8.0 for most homes and 9.0 above 5,000 square feet. A house under 1,500 square feet only counts as small with less than 300 square feet of fenestration, so a glass-heavy modern plan of that size moves up to the 8.0-credit target. None of this forbids big windows; it means the glass is balanced by better glazing, more insulation elsewhere or a stronger efficiency package, and the permit drawings must list the options chosen and their points.

Common ways to build this

Three common ways to lay this out. Yours does not have to match one exactly — this is a starting point for the conversation, not a catalog.

Single-slope modern

36' x 48' / 1,728 sq ft / 3 bed, 2 bath

A shed roof rising toward the view, a wall of glass on the high side and small windows on the low side, with bedrooms along the low wall. The roof drains to the back, away from the entry, and a flat canopy covers the front door.

Glass-gable great room

40' x 60' / 2,400 sq ft / vaulted great room at one end

A classic gable shell with one end wall glazed floor to ridge over the great room, the kitchen along one side and the bedrooms at the far end. The glazed gable faces the view; the long walls carry the solid wall area the energy calculation needs.

Modern with a black-box garage

1,900 sq ft living / 600 sq ft attached garage

A long, low house with a dark, windowless garage block at one end, joined through a mudroom. The garage carries the dwelling-garage separation from Table R302.6 and, in Washington, the dedicated electric vehicle charging circuit for new dwellings with attached garages.

Ways to build this

This layout can go together several ways. These are the service lines most relevant to it.

Custom Plans

Custom barndominium plans for Washington State: floor plans and permit drawings with the energy code credits and your site's design values built in.

Steel Construction

Steel and metal building construction in Washington State: red-iron frames for barndominiums and shops, designed to your county's snow and seismic values.

Metal Homes

Metal building homes in Washington State: steel-clad houses finished to the state energy code, with the insulation and condensation details done right.

Modern 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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Can a modern barndominium have a wall of glass in Washington?

Yes, but it is paid for elsewhere in the envelope. Washington's energy code sets a prescriptive window U-factor of U-0.30, and a house under 1,500 square feet loses the lower 5.0-credit target once its fenestration reaches 300 square feet. A glass-heavy plan is usually balanced with better windows, more insulation elsewhere or a stronger efficiency package.

What is the minimum window area for a room?

WAC 51-51-0303 requires glazing of at least 8 percent of each habitable room's floor area, unless artificial light gives an average of 6 footcandles over the room at 30 inches above the floor.

Does a flat or low-slope roof work in western Washington?

It works if it drains and the walls are protected. A single-slope roof should drain away from entries, and every door and large window benefits from an overhang or canopy. The roof covering has to suit its slope, and the roof is still drawn to the snow load the city or county sets.

Will a steel barndominium sweat inside?

It will if warm, damp indoor air reaches cold steel. The fix is a continuous air barrier and insulation that covers the girts and purlins rather than sitting between them, plus a dry crawl space or slab. Washington's code requires six-mil black polyethylene ground cover in a vented crawl space.

Is modern more expensive than a farmhouse style?

Style alone is not the driver; glass area, window quality and custom flashing details are. A modern plan with modest glazing on a simple shell can cost about the same as a farmhouse plan of the same size. Our cost guide covers the published ranges.

Is metal siding better in wildfire country?

Metal siding and a steel roof do not burn, which helps, but embers get in through vents, soffits and gaps, and decks and stored wood beside the wall can ignite. Plan the ground around the house as defensible space and detail vents and eaves for embers.

Where this plan fits in Washington

West of the Cascades a plan answers to rain and seismic design; east of them, to snow, sun, dry acreage and wildfire. These are the areas this layout suits best.

King County

Where modern design is most common, and where the rain decides how the clean lines are detailed.

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Kitsap County

Water-view parcels where a wall of glass faces the Sound and the roof has to handle the weather off it.

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Whatcom County

Northwest Washington acreage where a modern shell meets mountain views and wet winters.

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Chelan County

Dry-side sun and wildfire, where noncombustible metal and careful west glass pay off.

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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 2021 International Residential Code as amended by Washington (chapter 51-51 WAC) and the 2021 Washington State Energy Code, Residential (chapter 51-11R WAC), in force since March 15, 2024. The State Building Code Council has scheduled the 2024 editions to take effect May 3, 2027; the edition your permit is reviewed under governs.

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Tell us what you want to build and we will draw this 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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