DuplexHalf-PlexHouse TypesSide-by-Side December 8, 2025

Duplex vs. Half-Plex vs. Side-by-Side House: What’s the Difference?

Duplex vs. Half-Plex vs. Side-by-Side House: What’s the Difference?

When buyers and sellers talk about multi-unit homes, the terms can get confusing—duplex, half-plex, and side-by-side house often get used interchangeably, even though they describe different types of properties. Understanding these distinctions can help you price a property correctly, attract the right buyers, and market the unique advantages of each option.


What Is a Duplex?

A duplex is a single building that contains two separate living units, each with its own entrance, kitchen, and living spaces.
A duplex can be:

  • Side-by-side (units next to each other sharing one wall), or
  • Up-and-down (one unit on each floor).

Ownership:
A traditional duplex is owned by one owner, who owns both units on one parcel. However, in some markets, duplex units can be separated into two legal parcels (similar to a condo map), but this is less common.

Who it’s good for:

  • Investors wanting rental income
  • Multi-generational families
  • Owner-occupants offsetting costs by renting the other unit

What Is a Half-Plex?

A half-plex is essentially half of a duplex where each side is sold separately.
Think of it as a duplex that has been legally split into two individual properties, often with a shared wall—but each side has its own APN, lot, and deed.

Key features:

  • Each unit can be bought or sold independently
  • Owners are responsible for their own maintenance
  • No HOA in most cases
  • More affordable than a detached single-family home

Why buyers like them:
A half-plex offers the feel of a single-family home at a lower price point, with fewer maintenance obligations compared to a condo.


What Is a Side-by-Side House?

A side-by-side house usually refers to two separate homes built next to each other, often sharing a driveway or a zero-lot-line boundary.
The key difference is: these homes do NOT share a common wall.

This term is less formal but usually describes:

  • Two detached single-family homes sitting close together
  • Sometimes built on smaller lots or in infill developments
  • Each home has its own parcel and ownership, just like any other single-family residence

Why this matters:
A side-by-side house is not a duplex and not attached housing. It offers full privacy and independence, but with the benefit of a more affordable lot size.


Quick Comparison

Feature Duplex Half-Plex Side-by-Side House
Shared wall Yes Yes No
Number of legal parcels Usually 1 2 2
Sold independently? Typically no Yes Yes
Type of structure One building, two units One building split into two ownerships Two separate detached buildings
Best for Investors & multi-gen families Entry-level buyers, downsizers Buyers wanting privacy at a lower cost

Which Is Best for You or You?

  • Duplexes are ideal for investors and those looking to maximize rental income.
  • Half-plexes offer a great middle ground—affordable ownership with minimal shared responsibilities.
  • Side-by-side houses provide the privacy of single-family living while still being cost-effective compared to larger lot homes.

Each option serves a different purpose, and understanding the nuances helps buyers make confident decisions—and helps sellers market their property more effectively.


 

Steve Cardinalli
Real Estate Professional, 01323509
(760) 814-0248
Steve@Cardinalli.com
www.Cardinalli.com
Century 21 Affiliated Fine Homes & Estates
Village Faire in Carlsbad Village
300 Carlsbad Village Dr, 223
Carlsbad, CA 92008


Be the first to know about the market trend in your community at Neighborhood News