Rwanda Housing Authority – Incremental Housing and Other Design Principles for Low-Cost Housing

Incremental housing has emerged as a crucial solution to address the housing crisis in rapidly urbanizing regions, particularly in the Global South. The workshop hosted by the Rwanda Housing Authority (RHA) and the International Growth Centre (IGC) highlighted key design principles for a successful pilot incremental housing project. This approach focuses on land management, housing architecture, building materials, and infrastructure, drawing on international experiences and context-specific challenges and opportunities. This article will delve into these principles and explore how incremental housing can be a viable solution for low-income urbanization.

Effective land management is fundamental to the success of incremental housing projects. Sites-and-services plots require special planning and engineering standards to lower costs and support incremental building processes. Providing a package of basic needs at the time of allocation, including land, infrastructure, community services, and access to financing, is essential. Mechanisms combining savings, subsidies, and credit can help households finance and incrementally build their homes. The location of the subdivision is also critical for access to low-cost public transport, schools, and jobs, which are vital for the project’s success.

Incremental housing architecture prioritizes flexibility and adaptability. It starts with a basic structure that meets immediate needs and allows for gradual expansion and modification as circumstances evolve. Key features include modularity, expandability, adaptability, affordability, community participation, sustainability, and rapid deployment. For example, in informal settlements, residents often make gradual upgrades to their homes as resources allow. However, without proper support, these ad hoc upgrades can lead to unsafe construction and vulnerability to disasters. Incremental housing offers a structured approach to ensure safer and more resilient housing.

The choice of building materials significantly impacts the cost and sustainability of incremental housing projects. Locally available materials, such as compressed earth blocks and improved fired bricks, can reduce costs and support local economies. These materials are not only affordable but also environmentally friendly, aligning with the principles of sustainable construction. For instance, straw-tech model houses and earthbag construction are innovative examples of using locally sourced materials to build affordable and sustainable homes.

Infrastructure plays a vital role in the resilience and livability of incremental housing projects. The sites-and-services approach emphasizes the provision of basic infrastructure, such as water, sanitation, and electricity, to make subdivisions more livable. Infrastructure for resilience includes designing neighbourhoods to reduce risks of flooding, erosion, fire damage, and communicable diseases. For example, Durban, South Africa, and Rosario, Argentina, have upgraded infrastructure in vulnerable areas to enhance resilience. Efficient land use layouts and engineering norms appropriate for incremental development can also reduce the cost of infrastructure per plot.

The urbanization of the Global South between 1950 and 2020 has been unprecedented, occurring at more than double the speed of urbanization in the Global North. While urbanization in East Asia has been accompanied by strong economic and employment growth, migration to cities in Sub-Saharan Africa has often been driven by reasons other than job opportunities. This rapid, low-income urbanization has led to shortfalls in key urban success factors, such as infrastructure, education, financial access, and housing. Lessons from international experiences, such as the Baan Mankong program in Bangkok, Thailand, which has scaled up to over 215 cities in 19 Asian countries, can provide valuable insights for other regions.

Incremental housing offers a flexible and adaptable solution to the housing crisis in rapidly urbanizing regions. By focusing on land management, housing architecture, building materials, and infrastructure, incremental housing projects can address the needs of low-income households while promoting resilience and sustainability. Drawing on international experiences and context-specific challenges, incremental housing can pave the way for more inclusive and prosperous urban development.