Duplex: Side-by-Side


A small (1 to 2-story), detached structure that consists of two dwelling units arranged side-by-side, each with an entry from the street. This type has the appearance of a small-to-medium single-unit house and may include a rear yard.

Typical Specifications

Lot Front-loaded Rear-Loaded
Width* 55–75 feet 40–70 feet
Depth* 100–150 feet 100–150 feet
Area* 5,000–11,250 sq. ft. 4,500–10,500 sq. ft.
  0.11–0.26 acres 0.10–0.24 acres
Number of Units 2 units 2 units
Typical Unit Size 600–2,400 sq. ft. 600–2,400 sq. ft.
Net Density 8–17 du/acre 8–19 du/acre
Gross Density 6–13 du/acre 7–14 du/acre
Parking Ratio*
On-street Spaces 2–3 2–3
Off-street Spaces 1 per unit max. 1 per unit max.
Front* 10–25 feet
Side* 5–12 feet
Rear (main building)* 30–60 feet
Between Main and Accessory Buildings 10–20 feet
Building Size
Width 28–55 feet
Depth 28–60 feet
Height (to eave)* 14–24 feet
Floors 1-2 stories
* Varies based on context

Idealized specifications take the best characteristics of this type and update them for today’s typical building standards, serving as a model for new development.

Rear Loaded

Ideal Specifications

Width 50 feet
Depth 100 feet
Area 5,000 sq. ft.
  0.115 acres
Number of Units 2 units
Typical Unit Size 612 sq. ft.
Net Density 17 du/acre
Gross Density 12 du/acre
Parking Ratio 2 per unit
On-street Spaces 2
Off-street Spaces 2
Front 15 feet
Side 5 feet
Width 36 feet
Depth 34 feet
Height (to eave) 14 feet
Floors 1 story

The following example(s) show this housing type documented as real-world examples as they exist today. NOTE: Documented examples may be not be up to today’s local building code standards. See the Idealized tab for up-to-date specifications in line with modern building standards.