Backyard ADU / Granny FlatPlan HG-1173
640 Sq Ft (20x32) 1 Bed 1 Bath Backyard ADU / Granny Flat Floor Plan
640
Sq Ft
1
Beds
1
Baths
20x32
Shell
Shell Est: $30,000
20' × 32' Shell • 12 Floor Plans
20' × 32' Floor Plans (640 Sq Ft Base)
Compare 12 build-ready ways to configure a 20-foot by 32-foot structure—including all-living homes, shop-house splits, and 2-story lofts.
12 Plans
12 Plans
Backyard ADU / Granny FlatPlan HG-1174
641 Sq Ft (20x32) 2 Bed 1 Bath Backyard ADU / Granny Flat Floor Plan
641
Sq Ft
2
Beds
1
Baths
20x32
Shell
Shell Est: $30,000
A-Frame CabinPlan HG-1175
930 Sq Ft (20x32) 1 Bed 1 Bath A-Frame Cabin Floor Plan with Loft
930
Sq Ft
1
Beds
1
Baths
20x32
Shell
Shell Est: $42,500
A-Frame CabinPlan HG-1176
930 Sq Ft (20x32) 2 Bed 1 Bath A-Frame Cabin Floor Plan with Loft
930
Sq Ft
2
Beds
1
Baths
20x32
Shell
Shell Est: $42,500
Modern CabinPlan HG-1177
640 Sq Ft (20x32) 1 Bed 1 Bath Modern Cabin Floor Plan
640
Sq Ft
1
Beds
1
Baths
20x32
Shell
Shell Est: $29,000
Modern CabinPlan HG-1178
641 Sq Ft (20x32) 2 Bed 1 Bath Modern Cabin Floor Plan
641
Sq Ft
2
Beds
1
Baths
20x32
Shell
Shell Est: $29,000
Modular / Prefab CottagePlan HG-1179
640 Sq Ft (20x32) 1 Bed 1 Bath Modular / Prefab Cottage Floor Plan
640
Sq Ft
1
Beds
1
Baths
20x32
Shell
Shell Est: $27,500
Modular / Prefab CottagePlan HG-1180
641 Sq Ft (20x32) 2 Bed 1 Bath Modular / Prefab Cottage Floor Plan
641
Sq Ft
2
Beds
1
Baths
20x32
Shell
Shell Est: $28,000
Tiny Home on FoundationPlan HG-1181
640 Sq Ft (20x32) 1 Bed 1 Bath Tiny Home on Foundation Floor Plan
640
Sq Ft
1
Beds
1
Baths
20x32
Shell
Shell Est: $31,000
Tiny Home on FoundationPlan HG-1182
641 Sq Ft (20x32) 2 Bed 1 Bath Tiny Home on Foundation Floor Plan
641
Sq Ft
2
Beds
1
Baths
20x32
Shell
Shell Est: $31,000
Garage with Loft / Apartment AbovePlan HG-1183
642 Sq Ft (20x32) 1 Bed 1 Bath Garage with Loft / Apartment Above Floor Plan with Apartment Above
822
Sq Ft
1
Beds
1
Baths
460
Shop SF
Shell Est: $41,500
Garage with Loft / Apartment AbovePlan HG-1184
642 Sq Ft (20x32) 2 Bed 1 Bath Garage with Loft / Apartment Above Floor Plan with Apartment Above
822
Sq Ft
2
Beds
1
Baths
460
Shop SF
Shell Est: $41,500
20' × 32' Build Cost Guide, Nearby Sizes & FAQs
Slab takeoff, framing span notes, and comparable footprint sizes
20' × 32' Build Cost Guide, Nearby Sizes & FAQs
Slab takeoff, framing span notes, and comparable footprint sizes
Nearby Footprint Sizes:14'×32' (448 sf)14'×36' (504 sf)14'×40' (560 sf)16'×28' (448 sf)16'×30' (480 sf)16'×32' (512 sf)16'×36' (576 sf)16'×40' (640 sf)
20' Clear-Span Truss & Slab Engineering
A 20' × 32' rectangular building envelope (640 sq ft base area, 104 linear feet of exterior wall) is one of the most cost-effective structural modules in residential construction. Because the 20-foot width can be spanned by single-piece prefabricated wood roof trusses or cold-formed steel rafters, interior walls are non-load-bearing—allowing complete flexibility between open great rooms, split bedroom wings, and drive-in garage bays.
Material Takeoff Baseline (10 Cu. Yds. Concrete / 8 Roof Squares)
Every 4-corner 20x32 layout eliminates expensive hip-and-valley roof framing and minimizes foundation form corners. Builders typically budget 10 cubic yards of 4,000-PSI concrete for the monolithic slab, 88 exterior 2x6 studs (or 13 laminated post-frame columns at 8' o.c.), and 8 squares of standing-seam or ribbed metal roofing.
How many bedrooms and bathrooms fit inside a 20x32 (640 sq ft) floor plan?
A 20' × 32' building footprint (640 sq ft base area) comfortably supports 1 to 2 bedrooms and 1 bathroom in an open-concept ADU, tiny home, or cabin configuration. Browse all 12 vetted 20x32 floor plan variations above to compare room sizes.
How much concrete and roofing material does a 20x32 building require?
A 20' × 32' footprint has 104 linear feet of exterior perimeter wall. Pouring a 4-inch monolithic concrete slab with thickened perimeter grade beams requires approximately 10 cubic yards of ready-mix concrete. A standard gable roof with 18-inch overhangs requires roughly 8 roofing squares (800 sq ft of metal or shingle coverage).
What is the average cost to build a 20x32 house or barndominium?
Across our 12 engineered 20x32 blueprints, dried-in structural shell packages range from $19,200 to $30,720, while full turnkey construction averages $136,208 depending on whether the footprint is configured as all-living space or split between living quarters and an unheated shop bay.