21st Century Housing Act — Sec 210: Accelerating Home Building

Pre-Approved Housing
Ready to Build

Browse 24 pre-approved housing designs from ADUs to apartments. Get cost estimates, permit checklists, and start building faster with pattern book designs.

Free to browse Pre-approved designs Location-adjusted costs

Browse by Housing Type

Missing-middle housing designs for every community

ADU

Accessory Dwelling Units

400-800 sq ft

4 designs

Duplex

2-Unit Residential

1,800-2,800 sq ft

3 designs

Triplex

3-Unit Residential

2,700-4,200 sq ft

3 designs

Fourplex

4-Unit Residential

3,600-5,600 sq ft

3 designs

Townhouse

Attached Row Housing

1,400-2,200 sq ft

3 designs

Small Apartment

5-20 Unit Buildings

8,000-20,000 sq ft

3 designs

Mixed-Use

Residential + Commercial

6,000-12,000 sq ft

3 designs

Modular

Factory-Built Homes

1,000-1,800 sq ft

2 designs

Featured Designs

Popular pre-approved designs ready for your next project

Pre-Approved
ADU

Coastal ADU

Coastal Modern

600 sq ft 1 bed 1 bath
$95K - $130KView Details
Pre-Approved
Duplex

Craftsman Duplex

Craftsman

2,400 sq ft 4 bed 4 bath
$320K - $420KView Details
Pre-Approved
Fourplex

Modern Fourplex

Modern

4,800 sq ft 8 bed 8 bath
$580K - $750KView Details
Pre-Approved
Townhouse

Traditional Townhouse

Traditional

1,800 sq ft 3 bed 2.5 bath
$240K - $320KView Details
Triplex

Contemporary Triplex

Contemporary

3,600 sq ft 6 bed 6 bath
$450K - $580KView Details
Pre-Approved
Modular

Modular Home

Modern Farmhouse

1,400 sq ft 3 bed 2 bath
$160K - $220KView Details

How Pattern Book Works

1

Browse Designs

Explore pre-approved housing designs by type, style, size, and cost range. All designs are publicly available per Sec 210.

2

Get Local Costs

Enter your zip code for location-adjusted cost estimates using state-level construction cost multipliers.

3

Start Building

Select a design, get your jurisdiction-specific permit checklist, and submit for expedited review.

Why Use Pattern Book Designs?

Faster Permitting

Pre-approved designs often qualify for expedited permit review — saving weeks.

Known Costs

Every design includes assembly-level cost estimates adjusted for your location.

Act Compliant

Aligned with Sec 210 of the 21st Century Housing Act for pattern book housing.

Proven Designs

Each design has been reviewed by licensed architects and meets building codes.

Ready to Build Missing-Middle Housing?

Browse pre-approved designs, get instant cost estimates, and start the permitting process today.

Browse All Designs Check Zoning First