A Parametric, Geometry-Aware Residential Construction Cost Estimation Model for Ghana: Design, Validation, and the "Completeness Gap" in Informal Contractor Quotes
Research reveals informal contractor quotes omit critical components, causing widespread project abandonment in Ghana's housing crisis.
A research team from the University of Cape Coast and Kwame Nkrumah University of Science and Technology has developed GhanaHousePlanner (GHP), a parametric, geometry-aware AI model designed to solve Ghana's residential construction cost estimation crisis. The model addresses the country's two-million-unit housing deficit by tackling the 'completeness gap'—a systematic discrepancy where informal contractor quotes using flat per-square-metre pricing omit essential components like structural steel (Y16 rebar), plastering, floor screed, and full services. This leads to widespread project abandonment when funds run out mid-construction.
The GHP model operates through seven specialized calculation modules covering foundation, blockwork, cement, structural steel, roofing, plumbing, and electrical components. It features both a primary geometry-based mode and a formula-based fallback system. Validation against three real-world case studies (75, 120, and 200 square-meter homes) benchmarked with February 2026 market prices revealed shocking discrepancies: GHP's accurate estimates (GHS 519,000 to GHS 1,398,000) were 29% to 98% higher than typical informal quotes.
This research confirms that informal per-square-metre rates rarely cover requirements for code-compliant construction. The GhanaHousePlanner platform provides self-builders with transparent, auditable itemized bills of quantities (BoQ) that reflect true construction costs. Despite challenges like material price volatility and labor market informality, the tool establishes a framework for improving cost predictability and reducing project failure across sub-Saharan Africa's housing markets.
- GHP's AI model revealed informal quotes are 29-98% lower than actual costs by omitting structural steel, plastering, and services
- The parametric model uses seven calculation modules and was validated against three real-world case studies with 2026 market prices
- Addresses Ghana's 2-million-unit housing deficit by providing transparent, itemized bills of quantities to prevent project abandonment
Why It Matters
Provides a scalable solution to prevent construction project failure in emerging markets, potentially impacting millions of housing units.