NAIROBI, Kenya - On Thursday, 13 November 2025, as the national conversation continues to focus on the high cost of land as the primary obstacle to affordable housing, an investigation reveals a more insidious challenge significantly driving up construction costs: the poor quality of available land. Developers and homebuyers are increasingly grappling with the immense financial burden of building on problematic soils and in areas lacking basic infrastructure, issues that threaten to derail Kenya's ambitious Affordable Housing Programme (AHP).

The government aims to construct 200,000 affordable housing units annually to address a national deficit of nearly two million units. However, the push to find inexpensive land is forcing developers into areas plagued by geological and infrastructural challenges, leading to unforeseen expenses that are ultimately passed on to the buyer.

The Black Cotton Soil Menace

A primary culprit is the prevalence of black cotton soil, a type of expansive clay found in many parts of Kenya, including Nairobi, Kiambu, Kajiado, and Machakos. This soil is notorious for its tendency to swell significantly when it absorbs water and shrink dramatically when it dries. This constant cycle of expansion and contraction exerts immense pressure on building foundations, leading to severe structural problems like cracked walls, uneven settling, and, in worst-case scenarios, total structural failure.

According to engineering experts, standard strip foundations are often inadequate for such soil. Developers are forced to undertake costly and time-consuming measures. These include excavating the entire topsoil layer and replacing it with stable materials like murram, or constructing specialized, expensive foundations such as raft or pile foundations that can withstand the soil's movement. Michael Njahi, a quantity surveyor, noted that while land with black cotton soil may be cheaper to purchase, the necessary foundation work can increase final construction costs exponentially. These additional costs can range from hundreds of thousands to millions of shillings depending on the project's scale.

Infrastructure: The Missing Piece

Beyond soil quality, a critical issue is the lack of essential infrastructure in areas where land is more affordable. Many developers acquire land that is not serviced with access roads, water and sewer lines, or electricity. Chris Chege, a director at Shelter Afrique Development Bank, has highlighted the frustration of developers who must fund this infrastructure themselves, with these costs contributing up to 40 percent of a housing unit's final value.

The cost of building a single kilometre of tarmac road can range from KES 30 million to KES 60 million, while murram roads cost between KES 10 million and KES 20 million per kilometre. These are substantial expenses that developers must factor into their pricing, pushing the dream of an affordable home further out of reach for the average Kenyan, over 85% of whom earn less than KES 100,000 per month.

Regulatory Hurdles and Risky Lands

The pressure to build has also led to development on legally and environmentally risky lands, such as riparian reserves. The National Environment Management Authority (NEMA) defines riparian land as the area stretching a minimum of 6 metres and up to 30 metres from a river's highest water mark. Construction in these zones is illegal without express NEMA approval and an Environmental Impact Assessment (EIA), as it poses risks of flooding and ecological damage. Structures built on such land are subject to demolition, representing a total loss for investors and homeowners.

To combat these issues, the government has implemented stricter regulations. The National Building Code 2024, which took effect in March 2024, now mandates soil testing before any construction can begin. The National Construction Authority (NCA) is tasked with enforcing this code to ensure structural integrity and public safety. However, industry bodies like the Kenya Property Developers Association (KPDA) have pointed to opaque permitting processes and other regulatory bottlenecks as persistent challenges that delay projects and increase costs.

For Kenya's affordable housing agenda to succeed, a shift in focus is required. Simply targeting cheap land is not a sustainable solution. A more holistic approach is necessary, integrating thorough geotechnical surveys, strategic government investment in bulk infrastructure for new development zones, and the streamlined enforcement of building codes. Without addressing the foundational issues of land quality and infrastructure, the cost of housing will remain stubbornly high, and the structural integrity of new developments could be compromised.