Purpose: Continual cost reduction of overhead costs of building projects can realign the concept of post-contract cost control towards value-driven construction projects and stakeholders’ satisfaction. This study synthesised and analysed the viable continuous improvement measures critical for waste reduction during the execution phase of a building project. Design/methodology/approach: A review of existing literature facilitated a list of continuous improvement measures. This literature review findings enabled a Likert-scale questionnaire which was administered to two-hundred and fifty (250) small- and medium-scale construction companies (SMSCC) in Nigeria. Multiple linear regression statistical tests deduced the significant cost reduction measure from which a causal loop diagram was designed to indicate continuous improvement measures during the execution phase of a building project. Findings: Cogent construction activities associated with overhead costs were deduced from the statistical tests as being payment of suppliers and sub-contractors and purchase orders. An all-inclusive casual loop model for cost reduction through waste minimisation in construction projects as a viable oriented mechanism for meeting clients' requirements was developed. Practical implications: The causal loop continuous improvement model recognised external and internal factors which are crucial for SMSCC to focus on for their organisational growth and performance enhancement. Originality/value: A focus on non-physical waste in construction organisations potentially addresses behavioural challenges for continuous improvement.