Home » BIM and Architecture » How to design a two-family house with a BIM model

How to design semi-detached house_guide-with-example-project_EN

How to design a two-family house with a BIM model

Two-family house project: definitions, architecture, materials and a practical example with plans, elevations, cross-sections and a BIM model ready to use

The Two-family house type is a residential building that comes from the union of two different single-family units. It represents an excellent alternative to the isolated single-family house for a series of functional and economic advantages.

The two-family house offers the advantage of giving independence and comfort similar to those offered by a single-family house with lower costs for land acquisition and urbanization works. Moreover, thanks to the possible shared use of the technical systems (eg. heating, outdoor lighting, etc.) and maintenance, the management costs are lower than a typical single-family house.

How to design bifamiliar house_with a BIM software

Example of a Two-family house

In this focus we’ll be taking a closer look at a two-family house project, dealing with both the theoretical and practical aspects: from the definition of the building type to the modeling of a practical example which will be particularly useful as an example to follow and as a design guide.

living room BIM project

Living room – project created with Edificius

This two-family house project is available for download with all relevant technical drawings in dwg (plans, elevations, sections and axonometry) and the 3D model created entirely with an architectural BIM design software.



Semi-detached house – definitions

A two-family house is a building type normally combined of two independent single-family units.

Consisting of two housing units, generally one specular to the other, they are built on the same plot of land to increase density and optimize land use.

The two-family house has reduced dimensional characteristics compared to the average of the single-family house: its accommodations are generally of medium-small size. The distributional and functional characteristics are of course the same: the structure can develop across one floor or more, with a common a preference for this kind of solution.

How to design semi-detached house with BIM

Concept design | Area plan layout within the land plot

Housing characteristics

The two- family house contains two apartments that have at least one wall in common. This allows excellent distribution possibilities for the interior spaces.

Functional distribution diagrams

Concept design | planimetric diagrams of volumes and functional distribution

However, the two-family house type can also be characterized by particular design limits:

  • the open space is generally divided into two areas: reception on the front and private guests at the back of the house;
  • the small green area must be protected with hedges, walls, railings, pergolas, garages;
  • views are limited to only three sides.
Ground level BIM projecct

Semi-detached house | ground and first floor plans

Two-storey semi-detached house project: a practical example

Assessment and calculation of urban planning parameters

For the representation of our design we considered the settlement of a two-family house in a residential urban area. Here are some of the requirements that need to be followed:

  • Lot size: 700m²
  • Coverage ratio with respect to the surface of the land: 50%
  • Max number of floors: 2 floors
  • Max height: 50m
  • Distance from land plot contours: 5m or in adhesion

Distance from road: Respect existing alignments or 5m.

Because we need to respect the distances from the borders and from the road, we get the maximum area that can be occupied by the building which is roughly 287m².

For the configuration of the functional spaces of the two-family house, distributed on two floors, we get these sizes:

  • Surface ground floor for unit A: 115.00 m²
  • Surface ground floor for unit B: 114.00 m²
  • Surface first floor for unit A: 114.00 m²
  • Surface first floor for unit B: 116.00 m²
Two-family house_elevation_software-architecture-BIM-Edificius

Two-family house | Elevation view

The composition/distribution methodology

The preliminary task of the designer, or of the design team, will therefore be to try to study housing solutions where the maximum useful surface is obtained for both housing units.

The volume must then be created and modeled in order to create a shape that meets precise functional needs.

BIM kitchen

Kitchen project with a BIM software

Both houses are developed on two floors comprehensive of:

  • entrance/hallway, garage, services, living/dining/kitchen, on the ground floor;
  • three bedrooms, bathrooms, utility room and terraces, on the first floor.
Two family house_axonometric-isometric_software-architecture-BIM-Edificius

Two-family house | axonometric view

Characteristics of materials and colors

The two-family house has the entire external masonry facing covered with sandstone blocks interspersed, at the points of ‘excavation’ (setbacks, entrances, terraces), from simply plastered surfaces.

BIM project exterior

Project exterior view

The bush-hammered reinforced concrete was used to conform the walls of different heights that delimit the whole lot and separate the two houses.

North-west corner BIM project

North-west corner of the project

The driveways and pedestrian paths, as well as the paved areas of the gardens behind, are always in reinforced concrete slabs.

Entrance BIM project


The interiors have flooring in teak parquet planks arranged in a herringbone pattern, porcelain stoneware tiles, glazed wooden shutters with shutters and steel Cor-Ten railings.

Living room BIM project

Living room project

Software download, DWG project and two-family house model

All dwg drawings and the 3D model of the two-family house project created using Edificius, the architectural BIM design software, are available for download below free of charge.

Edificius - BIM - working drawings


Download the 3D BIM model (in the .edf file format) of the two-family house project

Download the IFC BIM model of the two-family house project

Download the DWG CAD drawings of the two-family house project