HOOLIEHAUSHouse Plans & 2D CAD Blueprints
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137 Duplex / Multi-Gen Floor Plans • 1,200–3,500 Sq Ft

Duplex / Multi-Gen Floor Plans & 2D Blueprints

Symmetric side-by-side duplexes featuring STC-60 double-stud acoustic party walls, mirrored plumbing wet cores for low-cost rough-in, separate utility meters, and private entries.

Duplex / Multi-Gen 3D House Exterior
137 Plans
40' × 40'
Duplex / Multi-GenPlan HG-1008

1,600 Sq Ft (40x40) 2 Bed 2 Bath Duplex / Multi-Gen Floor Plan

1,600
Sq Ft
2
Beds
2
Baths
40x40
Shell
Shell Est: $62,500
View Plan
44' × 24'
Duplex / Multi-GenPlan HG-1426

1,060 Sq Ft (24x44) 2 Bed 2 Bath Duplex / Multi-Gen Floor Plan

1,060
Sq Ft
2
Beds
2
Baths
24x44
Shell
Shell Est: $43,500
View Plan
44' × 24'
Duplex / Multi-GenPlan HG-1427

1,060 Sq Ft (24x44) 2 Bed 2 Bath Duplex / Multi-Gen Floor Plan (STC-60 Mirrored Acoustic Party-Wall Duplex)

1,060
Sq Ft
2
Beds
2
Baths
24x44
Shell
Shell Est: $43,500
View Plan
44' × 24'
Duplex / Multi-GenPlan HG-1428

1,060 Sq Ft (24x44) 3 Bed 2 Bath Duplex / Multi-Gen Floor Plan

1,060
Sq Ft
3
Beds
2
Baths
24x44
Shell
Shell Est: $43,500
View Plan
44' × 24'
Duplex / Multi-GenPlan HG-1429

1,060 Sq Ft (24x44) 3 Bed 2 Bath Duplex / Multi-Gen Floor Plan (STC-60 Mirrored Acoustic Party-Wall Duplex)

1,060
Sq Ft
3
Beds
2
Baths
24x44
Shell
Shell Est: $43,500
View Plan
Shell Est: $42,000
View Plan
Shell Est: $42,000
View Plan
40' × 26'
Duplex / Multi-GenPlan HG-1530

1,040 Sq Ft (26x40) 3 Bed 2 Bath Duplex / Multi-Gen Floor Plan

1,040
Sq Ft
3
Beds
2
Baths
26x40
Shell
Shell Est: $42,000
View Plan
40' × 26'
Duplex / Multi-GenPlan HG-1531

1,040 Sq Ft (26x40) 3 Bed 2 Bath Duplex / Multi-Gen Floor Plan (STC-60 Mirrored Acoustic Party-Wall Duplex)

1,040
Sq Ft
3
Beds
2
Baths
26x40
Shell
Shell Est: $42,000
View Plan
40' × 28'
Duplex / Multi-GenPlan HG-1646

1,120 Sq Ft (28x40) 2 Bed 2 Bath Duplex / Multi-Gen Floor Plan

1,120
Sq Ft
2
Beds
2
Baths
28x40
Shell
Shell Est: $45,000
View Plan
40' × 28'
Duplex / Multi-GenPlan HG-1647

1,120 Sq Ft (28x40) 2 Bed 2 Bath Duplex / Multi-Gen Floor Plan (STC-60 Mirrored Acoustic Party-Wall Duplex)

1,120
Sq Ft
2
Beds
2
Baths
28x40
Shell
Shell Est: $45,000
View Plan
40' × 28'
Duplex / Multi-GenPlan HG-1648

1,120 Sq Ft (28x40) 3 Bed 2 Bath Duplex / Multi-Gen Floor Plan

1,120
Sq Ft
3
Beds
2
Baths
28x40
Shell
Shell Est: $45,000
View Plan

Duplex / Multi-Gen Build Cost Guide & Frequently Asked Questions

Shell kit pricing (~$40/sq ft), framing specifications (2x6 Exterior + Double-Stud Insulated Acoustic Party Wall) & common questions

Structural Framing, Roof Pitch & Foundation Specs

Symmetric side-by-side duplexes featuring STC-60 double-stud acoustic party walls, mirrored plumbing wet cores for low-cost rough-in, separate utility meters, and private entries. Every duplex / multi-gen layout in this 137-plan hub is drafted on a true structural bay module (6" exterior walls, 4.5" interior partitions) using 2x6 Exterior + Double-Stud Insulated Acoustic Party Wall. Standard builds pair a Monolithic Concrete Slab w/ Dual Sewer/Water Stub-Outs with a 5:12 Architectural Shingle or Standing Seam Metal Hip/Gable, eliminating complex roof valleys and reducing framing labor by 18% to 25%.

Shell Kit vs. Turnkey Budgeting & Plumbing Optimization

With dried-in shell pricing averaging $40/sq ft and turnkey builds averaging $155/sq ft, the fastest way to lower construction costs on a duplex / multi-gen is consolidating mechanical runs. Our compositional CAD engine groups kitchens, baths, and laundry rooms along shared plumbing wet walls and keeps clear 36-inch circulation paths around every doorway and kitchen island.

How much does a Duplex / Multi-Gen cost to build per square foot?

Across our 137 engineered duplex / multi-gen floor plans, dried-in structural shell packages average $40 per sq ft ($48,000 to $140,000 depending on footprint size), while complete turnkey construction averages $155 per sq ft of heated living space and $50 per sq ft for integrated workshop/garage bays. The average turnkey build cost across this collection is $280,442.

What structural framing and foundation system is best for a Duplex / Multi-Gen?

Our duplex / multi-gen blueprints are engineered around 2x6 Exterior + Double-Stud Insulated Acoustic Party Wall paired with a Monolithic Concrete Slab w/ Dual Sewer/Water Stub-Outs and a 5:12 Architectural Shingle or Standing Seam Metal Hip/Gable. All exterior walls are dimensioned at 6 inches with 4.5-inch interior partitions for straightforward permitting and local lumber or kit takeoff.

Are these Duplex / Multi-Gen floor plans compliant with IRC residential building codes?

Yes. Every duplex / multi-gen blueprint in the HoolieHaus StructuraCAD catalog is programmatically verified against 2024 International Residential Code (IRC) spatial standards—including R304 minimum room areas (70+ sq ft bedrooms, 7'-0" minimum width), R310 emergency egress window placement in all sleeping quarters, 36-inch main entry doors, and consolidated wet-wall plumbing cores.