Backyard ADU / Granny FlatPlan HG-1047
322 Sq Ft (16x20) 1 Bed 1 Bath Backyard ADU / Granny Flat Floor Plan
322
Sq Ft
1
Beds
1
Baths
16x20
Shell
Shell Est: $15,000
ADU & Granny Flat Guide24 Plans Compared
24 Backyard ADU & Granny Flat Floor Plans Under 1,000 Sq Ft (1 & 2 Bedroom Layouts)
Code-compliant detached accessory dwelling unit blueprints from 320 to 1,000 sq ft engineered for narrow urban setbacks, aging-in-place accessibility, and rental income.
Part 1 of 4
1. Compact 350 to 550 Sq Ft 1-Bedroom Backyard Cottages
Designed for tight urban rear yards and 4-foot side setbacks, these micro-ADUs pack a full kitchen, private bedroom, and accessible bath into a tiny footprint.
Backyard ADU / Granny FlatPlan HG-1098
432 Sq Ft (18x24) 1 Bed 1 Bath Backyard ADU / Granny Flat Floor Plan
432
Sq Ft
1
Beds
1
Baths
18x24
Shell
Shell Est: $20,500
Backyard ADU / Granny FlatPlan HG-1103
504 Sq Ft (18x28) 1 Bed 1 Bath Backyard ADU / Granny Flat Floor Plan
504
Sq Ft
1
Beds
1
Baths
18x28
Shell
Shell Est: $24,000
Backyard ADU / Granny FlatPlan HG-1150
562 Sq Ft (20x28) 2 Bed 1 Bath Backyard ADU / Granny Flat Floor Plan
562
Sq Ft
2
Beds
1
Baths
20x28
Shell
Shell Est: $26,500
Backyard ADU / Granny FlatPlan HG-1113
576 Sq Ft (18x32) 1 Bed 1 Bath Backyard ADU / Granny Flat Floor Plan
576
Sq Ft
1
Beds
1
Baths
18x32
Shell
Shell Est: $27,500
Backyard ADU / Granny FlatPlan HG-1287
577 Sq Ft (24x24) 2 Bed 1 Bath Backyard ADU / Granny Flat Floor Plan (Consolidated Wet-Wall + Open Great Room)
577
Sq Ft
2
Beds
1
Baths
24x24
Shell
Shell Est: $26,500
Part 2 of 4
2. 600 Sq Ft ADU Floor Plans (The Impact-Fee Sweet Spot)
In many municipalities, ADUs at or under 600–750 sq ft are exempt from school and municipal development impact fees—saving homeowners $8,000 to $20,000 immediately.
Backyard ADU / Granny FlatPlan HG-1219
616 Sq Ft (22x28) 1 Bed 1 Bath Backyard ADU / Granny Flat Floor Plan
616
Sq Ft
1
Beds
1
Baths
22x28
Shell
Shell Est: $28,500
Backyard ADU / Granny FlatPlan HG-1083
640 Sq Ft (16x40) 2 Bed 1 Bath Backyard ADU / Granny Flat Floor Plan
640
Sq Ft
2
Beds
1
Baths
16x40
Shell
Shell Est: $30,500
Backyard ADU / Granny FlatPlan HG-1126
648 Sq Ft (18x36) 2 Bed 1 Bath Backyard ADU / Granny Flat Floor Plan
648
Sq Ft
2
Beds
1
Baths
18x36
Shell
Shell Est: $30,500
Backyard ADU / Granny FlatPlan HG-1303
674 Sq Ft (24x28) 2 Bed 1 Bath Backyard ADU / Granny Flat Floor Plan
674
Sq Ft
2
Beds
1
Baths
24x28
Shell
Shell Est: $31,000
Backyard ADU / Granny FlatPlan HG-1242
704 Sq Ft (22x32) 2 Bed 1 Bath Backyard ADU / Granny Flat Floor Plan
704
Sq Ft
2
Beds
1
Baths
22x32
Shell
Shell Est: $33,000
Backyard ADU / Granny FlatPlan HG-1317
721 Sq Ft (24x30) 2 Bed 1 Bath Backyard ADU / Granny Flat Floor Plan
721
Sq Ft
2
Beds
1
Baths
24x30
Shell
Shell Est: $33,500
Part 3 of 4
3. 750 to 850 Sq Ft 2-Bedroom Detached Casitas
Adding a second bedroom dramatically increases monthly rental yield and allows a caregiver or home office alongside the primary suite.
Backyard ADU / Granny FlatPlan HG-1332
768 Sq Ft (24x32) 2 Bed 1 Bath Backyard ADU / Granny Flat Floor Plan (Split-Bedroom Privacy Wing + Center Great Room)
768
Sq Ft
2
Beds
1
Baths
24x32
Shell
Shell Est: $35,000
Backyard ADU / Granny FlatPlan HG-1452
780 Sq Ft (26x30) 2 Bed 1 Bath Backyard ADU / Granny Flat Floor Plan (Consolidated Wet-Wall + Open Great Room)
780
Sq Ft
2
Beds
1
Baths
26x30
Shell
Shell Est: $36,000
Backyard ADU / Granny FlatPlan HG-1208
800 Sq Ft (20x40) 2 Bed 2 Bath Backyard ADU / Granny Flat Floor Plan
800
Sq Ft
2
Beds
2
Baths
20x40
Shell
Shell Est: $37,500
Backyard ADU / Granny FlatPlan HG-1559
840 Sq Ft (28x30) 1 Bed 1 Bath Backyard ADU / Granny Flat Floor Plan
840
Sq Ft
1
Beds
1
Baths
28x30
Shell
Shell Est: $38,500
Backyard ADU / Granny FlatPlan HG-1358
866 Sq Ft (24x36) 1 Bed 1 Bath Backyard ADU / Granny Flat Floor Plan
866
Sq Ft
1
Beds
1
Baths
24x36
Shell
Shell Est: $40,000
Backyard ADU / Granny FlatPlan HG-1274
881 Sq Ft (22x40) 2 Bed 2 Bath Backyard ADU / Granny Flat Floor Plan
881
Sq Ft
2
Beds
2
Baths
22x40
Shell
Shell Est: $41,000
Part 4 of 4
4. Full-Size 850 to 1,000 Sq Ft Multi-Generational Granny Flats
Spacious single-level residences featuring L-shaped or island kitchens, walk-in closets, and wide covered front porches.
Backyard ADU / Granny FlatPlan HG-1749
900 Sq Ft (30x30) 1 Bed 1 Bath Backyard ADU / Granny Flat Floor Plan
900
Sq Ft
1
Beds
1
Baths
30x30
Shell
Shell Est: $41,000
Backyard ADU / Granny FlatPlan HG-1496
936 Sq Ft (26x36) 1 Bed 1 Bath Backyard ADU / Granny Flat Floor Plan
936
Sq Ft
1
Beds
1
Baths
26x36
Shell
Shell Est: $43,000
Backyard ADU / Granny FlatPlan HG-1387
961 Sq Ft (24x40) 2 Bed 2 Bath Backyard ADU / Granny Flat Floor Plan (Split-Bedroom Privacy Wing + Center Great Room)
961
Sq Ft
2
Beds
2
Baths
24x40
Shell
Shell Est: $44,000
Backyard ADU / Granny FlatPlan HG-1772
962 Sq Ft (30x32) 2 Bed 2 Bath Backyard ADU / Granny Flat Floor Plan (Split-Bedroom Privacy Wing + Center Great Room)
962
Sq Ft
2
Beds
2
Baths
30x32
Shell
Shell Est: $43,500
Backyard ADU / Granny FlatPlan HG-1610
1,009 Sq Ft (28x36) 2 Bed 2 Bath Backyard ADU / Granny Flat Floor Plan
1,009
Sq Ft
2
Beds
2
Baths
28x36
Shell
Shell Est: $46,500
Backyard ADU / Granny FlatPlan HG-1532
1,042 Sq Ft (26x40) 2 Bed 2 Bath Backyard ADU / Granny Flat Floor Plan
1,042
Sq Ft
2
Beds
2
Baths
26x40
Shell
Shell Est: $48,000
Planning Overview & Frequently Asked Questions
Build costs, structural comparisons & answers for 24 Backyard ADU Plans (<1,000 Sq Ft)
Planning Overview & Frequently Asked Questions
Build costs, structural comparisons & answers for 24 Backyard ADU Plans (<1,000 Sq Ft)
Statewide zoning reforms across California, Washington, Oregon, Texas, Florida, and the Northeast have made detached Backyard ADUs (Accessory Dwelling Units) one of the highest-ROI residential investments available. Whether you are housing aging parents or building a long-term rental casita, staying under key municipal thresholds (600 sq ft, 800 sq ft, or 1,000 sq ft) often waives impact fees and streamlines permit approval.
We selected 24 IRC-vetted backyard ADU floor plans under 1,000 sq ft below. Every design consolidates kitchen, bath, and laundry rough-ins along a single wet wall to cut plumbing trenching costs in half while preserving generous 36-inch doorways and private covered patios.
Why is 600 to 800 sq ft the most popular size for a backyard ADU?
Most state ADU mandates require cities to approve detached ADUs up to 800 sq ft by-right with minimal 4-foot rear and side setbacks, and many jurisdictions waive municipal impact fees for units under 750 sq ft.
How much does it cost to build a detached backyard ADU?
Depending on regional labor rates and utility trenching distance from the main house, dried-in ADU shell packages run $18,000 to $45,000, while complete turnkey builds typically range from $75,000 to $175,000.
Do these ADU floor plans include egress windows and 36-inch doors?
Yes. Every ADU plan in our catalog includes a 36-inch main entry door, IRC R310 emergency egress windows in every bedroom, and consolidated wet-wall plumbing.
