Build a 400 sq ft tiny house, backyard ADU, or guest house with this complete 20x20 one-bedroom plan. The single-story layout includes an open living and kitchen area, full bathroom with tub, in-unit washer/dryer, closet, and a loft plan — perfect for rental income, aging parents, or a first home. Instant digital download includes print-ready PDF plans, CAD file, itemized material list, and a reverse plan depending on your package. Every sheet is included: floor plans, elevations, sections, foundation, framing, electrical, and plumbing. Estimated build cost: $52,000–$88,000.
Full specifications
| Plan number | 25186 |
| Style | Home Plan Blueprint |
| Heated area | 400 sq ft (ANSI Z765) |
| Width and depth | 20'x20' |
| Floors | 1.5 |
| Roof pitch | 9:12 |
| Roof style | Steep gable |
| Framing | 2x4 |
| Garage detail | None |
| Foundation | Slab/Pier |
| Design standard | 2021/2022 IRC with amendments |
| Files delivered | Print-ready PDF + editable CAD (.dwg), with five printed sets available as an add-on |
| License | Single build licence as standard. Additional and unlimited build licences available in the purchase panel; the Complete Build Package includes unlimited builds |
| Delivery | Instant download + email, lifetime re-download |
What's included in this house plan?
A complete working drawing set, delivered as a print-ready PDF at A0 sheet size (33.1 x 46.8 in).
- Complete Architectural Floor Plans
- Loft & Open Living Space Layouts
- Roof, Ceiling & Building Section Drawings
- Exterior Elevations from All Sides
- Kitchen & Bathroom Construction Details
- Door, Window & Opening Schedules
- Electrical & Plumbing Layout Plans
- Wall, Rafter & Foundation Details
- Material List for Construction Planning
- Builder-Ready House Blueprints in PDF Format
Which build licence do you need?
| One home | Included with every package. You may build a single dwelling from this plan set on one lot. Keep the files for life and re-download whenever you need them. |
| Several homes | Add one build licence for each extra home, $499.00 apiece. The drawings do not change; the licence simply covers more dwellings. Common for spec builders putting up two or three of the same model. |
| Unlimited homes | $1,499.00 removes the build limit permanently, on any number of lots. Already included at no extra cost in the Complete Build Package. |
| What no licence allows | Reselling, sharing, sub-licensing or republishing the drawings themselves, in any format. The licence covers construction, not redistribution. |
| Upgrading later | You can buy an additional or unlimited licence at any time after your original order. Email us your order number and we will apply it to the same plan. |
Prefer paper? Add five printed sets.
| What arrives | Five complete construction sets printed full size on 24 x 36 inch bond paper, folded and boxed, plus the same instant PDF download. |
| Why five | One for the permit office, one for your lender or appraiser, one for your framer, one for your subs and one to keep clean on your own desk. |
| Cost | $379.00 plus shipping, calculated at checkout from your address. |
| Turnaround | Printed to order and dispatched within 3 to 5 business days. Your digital files are delivered the moment you pay, so nothing waits on the post. |
| Revisions | Prints are produced from the plan as drawn. If you are also ordering modifications, wait for the revised set before adding prints so the paper matches the final design. |
About this house plan
A Complete 400 Sq Ft Tiny House Plan Built for Real Life
Whether you're adding a backyard ADU for rental income, building a guest house for family, or starting small with your first owner-built home, this 20x20 one-bedroom plan packs everything you need into a smart, buildable footprint.
The Layout
Step through the covered entry with double glass doors into an open living room (9'5" x 12'8") that flows straight into a full kitchen (9'5" x 6'6"). The bedroom (9'5" x 9'6") fits a queen bed and sits next to a dedicated closet (5'9" x 3'0") and a full bathroom (9'5" x 5'10") with tub, toilet, and vanity. A stacked washer/dryer closet means no trips to the laundromat. Large windows on every side fill the space with natural light, and a loft plan is included in the drawing set for extra sleeping or storage space.
Key Specs
- Conditioned living area: 400 sq ft
- Footprint: 20 ft x 20 ft
- Bedrooms: 1 | Bathrooms: 1 full
- Building height: 19'3" with 12 ft plate and 9 ft openings
- Gable roof with black corrugated metal roofing
- T&G cedar rain-screen siding over insulated 2x4 walls
What's Included
Your purchase includes the complete working drawing sheet set as a print-ready PDF at A3 size, plus a CAD file so your local designer or engineer can make edits. Depending on your plan package, you also receive the itemized material list and a reverse (mirrored) plan. The set covers the ground floor plan, loft plan, slab layout showing the load-bearing wall, sections, ceiling and roof outlines, all four elevations, kitchen and bath detail sheets, rafter details with five insulation options, wall and window installation details, foundation details with insulation and drainage specs, cedar siding rain-screen details, door and window schedule, framing details, a full electrical plan with fixture legend, a complete plumbing plan, and an itemized material takeoff your lumber yard can price directly.
Construction You Can Trust
The plan is drawn to 2022 California residential codes (IRC 2021 with amendments) with wind loads per ASCE 7-16. Details go beyond the basics: rigid foundation insulation, under-slab vapor barrier, perimeter drainage, termite shield, GFCI-protected electrical with interconnected smoke detectors, a 220V receptacle, and low-flow plumbing fixtures on copper supply with PVC Schedule 40 DWV.
Estimated Build Cost
Roughly $130–$220 per square foot depending on region, finishes, and labor, or approximately $52,000 to $88,000 total.
Instant Digital Download
Files are delivered immediately after checkout. Print at 100% scale at any local print shop. This is a digital product only; no physical item ships. Plans should be reviewed by a local engineer or building official before permitting, as codes vary by jurisdiction. For personal use only. © Home Plan DIY.
What will it cost to build?
Pick your state or set your own rate. We'll estimate from this plan's 400 sq ft.
Building codes & your state
Need changes? We modify any plan.
Move a wall. Add a garage. Flip the layout.
Send us your changes; most modification quotes come back within 24 hours.
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