A compact 30x40 barndominium sized like a starter home or cabin, with a covered entry porch and no large shop bay.

3 Bedroom Barndominium Floor Plans in Oregon

Three bedrooms is the most common family barndominium program: a primary suite, two secondary bedrooms, two baths, an open kitchen and living room, and a mudroom off the garage or shop. It usually lands between 1,500 and 2,000 square feet of living space, which fits a 30x50 or 40x50 footprint, or a 30x40 with part of it upstairs. On a rural Oregon parcel the bedroom count does more than set the room list. It is the number the septic system is sized from.

What actually changes with this feature

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

An escape window in every bedroom

Each sleeping room needs an emergency escape and rescue opening: under ORSC Section R310.2, at least 5.7 square feet net clear (5 square feet at grade floor), 24 inches of clear height, 20 inches of clear width, and a sill no more than 44 inches above the floor. In a steel building with widely spaced girts, place the openings with the wall framing, not after it.

Split bedrooms across the living space

The layout most families pick puts the primary suite at one end of the building and the two secondary bedrooms at the other, with the kitchen and living room between. It gives parents and children, or owners and guests, a quiet wall of separation, and in a rectangular barndominium it falls naturally out of the long, open span.

The home office question

A fourth room used as an office is useful, but if it has a closet, an egress window and a door off the hall, the building department may count it as a bedroom, and so may the septic sizing. Up to four bedrooms the minimum tank size does not change, but the design flow and drainfield can. Decide on paper whether the room is a bedroom.

A mudroom between the weather and the house

Rural Oregon families come in wet, muddy, or dusty depending on the side of the Cascades. A mudroom at the garage or shop entry, with a bench, lockers, a laundry and ideally a utility sink, keeps it out of the open kitchen that a barndominium plan puts right inside the door.

A compact 30x40 barndominium sized like a starter home or cabin, with a covered entry porch and no large shop bay.
Bedrooms and the septic system

On a septic parcel, the plan's bedroom count is a design number

Oregon's onsite wastewater rules, OAR 340-071, size a house's system by its bedrooms, and they define a bedroom as any room within a dwelling accepted as a bedroom by the state or local building department. That means a room drawn as a den, office or bonus room can be counted if it looks and works like a bedroom. The septic tank for a single-family dwelling with four bedrooms or fewer must hold at least 1,000 gallons, and the drainfield is sized from the design flow and the soils. Before any of that, OAR 340-071-0150 makes a site evaluation the first step toward a permit: test pits are dug and the county or DEQ agent reports whether the site suits an onsite system. Get the site evaluation early, and draw the bedrooms you intend to permit.

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.

Split-bedroom single storey

1,800 sq ft living (40' x 45') / 2 baths

Primary suite with a walk-in closet at one end; two bedrooms and a shared bath at the other; a vaulted great room and kitchen with an island in the middle. The mudroom and laundry connect to an attached garage.

Compact three-bedroom

1,500 sq ft living (30' x 50') / 2 baths

A narrow plan with bedrooms along one long wall and the living space along the other, each bedroom window on the outside wall. Economical to frame and easy to orient toward a view.

Three bedrooms with a shop

1,700 sq ft living / 1,200 sq ft shop under one roof

A three-bedroom house joined to a shop through a mudroom. The shop wall is the garage separation, and no bedroom opens directly into it.

3-Bedroom 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 big is a 3 bedroom barndominium?
Most land between 1,500 and 2,000 square feet of living space, on footprints such as 30x50, 40x45 or 40x50. A 30x40 can hold three bedrooms if part of the plan goes upstairs or the rooms are kept compact.
Does a home office count as a bedroom for the septic system?
It can. OAR 340-071 defines a bedroom as any room within a dwelling accepted as a bedroom by the state or local building department. If the room is drawn and built like a bedroom, expect it to be counted.
What size septic tank does a 3 bedroom house need in Oregon?
OAR 340-071 requires at least 1,000 gallons for a single-family dwelling with four or fewer bedrooms. The drainfield and any treatment unit are sized from the design flow and the site evaluation, which the county or DEQ agent issues.
Do all three bedrooms need egress windows?
Yes. Every sleeping room needs an emergency escape and rescue opening meeting ORSC Section R310: 5.7 square feet net clear (5 at grade floor), 24 inches high, 20 inches wide, and no more than 44 inches from floor to sill.
Can I build a 3 bedroom barndominium on farm-zoned land?
Only where the county approves a dwelling on the parcel. On land zoned for exclusive farm use, ORS 215.283 and 215.284 allow a house only in listed situations, so the land-use approval comes before the floor plan is final.
Single storey or two storeys for three bedrooms?
A single storey gives step-free living and a simple roof; two storeys put the same rooms on a smaller slab and roof. On a tight homesite or a sloped parcel, two storeys often fit better; on open acreage, most families choose one level.

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

Sources

Code figures on this page are from the 2023 Oregon Residential Specialty Code. The Building Codes Division anticipates a 2026 edition from October 1, 2026, with a six-month phase-in; the edition your permit is reviewed under governs.

  1. Oregon Secretary of State — OAR 340-071, Onsite Wastewater Treatment Systems
  2. ICC — 2023 Oregon Residential Specialty Code, Chapter 3 Building Planning
  3. Oregon Building Codes Division — 2023 ORSC Section R310 amendment, Emergency escape and rescue openings
  4. Oregon Revised Statutes chapter 215, County Planning; Zoning (ORS 215.283, 215.284)

Start your plans

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.