Side by Side House Definition and Market Overview
A side by side house refers to a residential layout where two or more dwelling units share a common wall, often marketed as duplexes, twin homes, or multi-family side-by-side configurations. These designs maximize lot usage while offering separate entrances, making them popular in urban infill and suburban neighborhoods. Major homebuilders such as Lennar and DR Horton regularly include side-by-side floor plans in their multi-family and mixed-use communities, targeting first-time buyers and investors alike.
According to the National Association of Home Builders, multi-family housing starts have remained a steady segment of total single-family construction, with side-by-side and duplex configurations representing a notable share of permits issued in 2023. The U.S. Census Bureau's Housing Starts report tracks these trends, showing consistent demand for efficient lot configurations in metropolitan areas where land costs push developers toward side-by-side designs.
Cost, Plans, and Financing for Side by Side Houses
Construction costs for a side by side house vary by region, materials, and finishes, but industry data from HomeAdvisor and BuildZoom suggests that building a duplex or twin home typically costs between $150,000 and $400,000 per unit, depending on square footage and local labor rates. Standard side-by-side plans often range from 1,200 to 2,400 square feet per unit, with two-car garages and open-concept living areas as common features. Architects and plan websites such as Architectural Designs and ePlans offer hundreds of pre-engineered side-by-side layouts that comply with local building codes.
Financing a side by side house can involve conventional mortgages, FHA 203(k) loans for renovation, or portfolio loans from banks experienced with multi-family properties. The Federal Housing Administration provides guidelines for owner-occupied duplexes, allowing lower down payments while treating the property as a primary residence. Investors often use the rental income from one side to qualify for the mortgage on the other, a strategy documented by Fannie Mae and Freddie Mac in their single-unit and small-multiplex lending programs.
Investment Potential and Regulatory Considerations
Side by side houses offer strong investment potential due to the ability to live in one unit and rent the other, creating a built-in income stream that can offset mortgage payments. Data from Zillow and Realtor.com indicates that duplex and multi-family properties in major metros often appreciate faster than single-family homes, especially in supply-constrained markets where lot efficiency is prized. The IRS allows owners to deduct depreciation on rental units and claim the mortgage interest deduction, making side-by-side configurations a tax-advantaged entry point into real estate investing.
Local zoning and building codes heavily influence side-by-side construction, with many municipalities requiring separate utility meters, fire-rated party walls, and specific setback distances. The International Code Council publishes the International Residential Code, which sets baseline standards for duplex and side-by-side construction, while individual cities may impose additional overlay zones or historic district restrictions. Before building or buying, investors should consult local planning departments and review SEC filings for publicly traded homebuilders to understand current supply trends and regulatory risks.