The Differences Between a Halfplex and Duplex

duplexes at dusk

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The reason a duplex and halfplex seem to confuse people is probably due to the last half of the word, plex. Plex can be a mirror image or two or more spaces that make up an investment property such as a fourplex, which would be four units. In this same line of reasoning, a halfplex would be one-half of one unit, but it's not. In some parts of the country, a halfplex is called a side-by-side. Although a halfplex is not a duplex, it's similar to one-half of a duplex.

Halfplexes are popular among first-time home buyers because it is generally much less expensive to buy a halfplex than to purchase a free-standing single family home. It is similar to taking a four bedroom, two bath home, and splitting the structure into two units, each consisting of two bedrooms, one bath (or any other configuration).​

Differences Between a Halfplex and a Duplex

A duplex is two units attached and deeded as one parcel. Think of it as a 2-unit residential building with a shared common wall or ceiling. Each unit may be identical to each other in size and configuration, or it may be different -- such as a one bedroom, one bath on one side and a three bedroom, two bath on the other. Duplexes can be side by side, one story, or a two-story structure with one unit upstairs and one unit down.

A halfplex is one-half of an attached residence. You will find two halfplexes per building, but each is deeded separately, and each has its own parcel number. Generally, a halfplex is a personal residence, but it could also be an investment property.

Halfplexes tend to mirror each other; each side may be the same. They do not share common floor space, that is they are not generally built on top of each other but are situated side by side.

Halfplexes usually share a backyard, divided by a fence. For all practical purposes, a halfplex is like a single family residence that shares a common wall. Sometimes they are separated by the garages.

How Maintenance Is Handled on a Halfplex

Unless the halfplex sits within the confines of a homeowner's association, generally each separate owner is responsible for maintaining the halfplex and its land. Here are common maintenance issues that should be considered before buying a halfplex:

  • Painting the Exterior of a Halfplex: You will see colorful Victorians in San Francisco or attached housing units in Ireland painted a variety of colors. However, in most communities in America, people want the exterior of their homes to match. It means if you want to change the exterior color of your home, you may want to encourage your attached neighbor to participate in the cost and labor to repaint. If your neighbor decides to paint his or her side a bright purple, there may not be anything you can do about it. Another good reason to talk to the neighbors before buying a home.
  • Refinishing or Replacing a Halfplex Driveway: I once owned a home with a shared driveway. My neighbors did not want to pay to pour an asphalt drive. They overheard me talking on my cell phone outside about putting a fence down the middle of the driveway and suddenly decided to ante up half the cost of new asphalt. However, if each of you has your own driveway, then cooperation is unnecessary.
  • Repairing or Replacing the Roof of a Halfplex: Ask any roofer about insurance companies who want to pay to reroof only half of a roof after a hailstorm, and you'll quickly find out that's not the best option. You can make repairs to your own roof, but if it has to be replaced in its entirety, you will need to come to an agreement with your neighbor or pay for it yourself.
  • Installing a Fence in the Yard of a Halfplex: Usually, only one fence will separate your yard from your attached neighbor's yard. Depending on the configuration of your yard, you may have another neighbor on the opposite side plus a different neighbor behind you. Most fences are shared, so to put in a new fence, you may need to talk with 3 or more neighbors and get each to agree to share a proportionate share of the cost. If none will agree, a remaining option is to build a new fence in front of the old fence and absorb the cost yourself. But you will lose at least six inches of yard space this way.
  • Repairing Adjoining Walls: Generally, you will own to the center of a common wall. It means if you have water damage or a hole in the wall, repairing your side of the wall is at your expense.

Before you buy a halfplex, it's a good idea to walk through the neighborhood. Meet up with other halfplex owners and talk about the community. Consider buying flood insurance for your halfplex and maintain your own insurance policy.