The Impact of Design Changes on Cost and Time Performance in Luxury Residential Construction Projects in South Jakarta

Design changes are among the most common factors affecting construction project performance, particularly in terms of cost and schedule. This study aims to analyze the impact of design changes on project cost and duration in several luxury residential construction projects located in South Jakarta. Data were collected through questionnaires distributed to 30 respondents consisting of contractors, consultants, and site supervisors involved in these projects. The collected data were analyzed using descriptive statistics, correlation analysis, and simple linear regression with SPSS software.

The results of the analysis show that design changes have a moderate and statistically significant positive relationship with project duration (r = 0.486, Sig. = 0.006), indicating that more frequent or extensive design revisions tend to extend project completion time. Conversely, the correlation between design changes and project cost was found to be weak and statistically insignificant (r = 0.212, Sig. = 0.261), implying that design modifications do not significantly contribute to cost escalation in these projects. The regression equation obtained for project duration is Y = 13.591 + 0.465X, indicating that each unit increase in design changes adds 0.465 units of time to project completion.

These findings suggest that while design changes are inevitable in high-end residential projects, their time impact is more pronounced than their cost impact. Therefore, effective design coordination, early design finalization, and structured change management are essential to mitigate schedule delays and enhance project performance.