Doppelhäuser

Doppelhäuser, or duplex houses, are a housing form consisting of two single-family homes built side by side and sharing a common party wall. The two dwellings form a paired unit with separate entrances and private outdoor space, such as gardens or courtyards. Exterior designs are often symmetrical or mirror-imaged, though variations exist.

Layout and design: Most duplexes are two-storey, sometimes with an attic or basement. Each unit has its own living areas, kitchen, bathrooms, and bedrooms; floor plans are typically mirror images, but asymmetrical layouts are also used. The dividing wall is a fire-resistant party wall to meet safety standards.

Construction: Common materials include brick, render, or timber frame. Insulation and soundproofing are important, particularly for the shared wall. Energy-efficient variants may include double glazing, modern insulation, and independent heating for each unit.

Variants and terminology: In German usage, the whole structure is called a Doppelhaus; a single dwelling within is a Doppelhaushälfte. Some designs have two separate roofs, others share a roof. The arrangement often allows each unit to be owner-occupied or rented.

Advantages: Efficient land use, reduced construction costs per unit, and opportunities for owner-occupation with a garden. The design can accommodate intergenerational living if two entrances are maintained.

Disadvantages: Potential noise transfer through the party wall, limited exterior customization due to twin design, and often stricter fire-safety considerations.

History and usage: The duplex form emerged in Europe in the 19th and 20th centuries to meet housing demand and became common in post-war suburban development. Today, duplexes remain widespread in many countries, including Germany, Austria, and Switzerland.