During operation in the coal-fired power plant, the cyclic operation of the plant exposes components and systems such as boilers to high pressure and temperature, resulting in mechanical and thermal fatigue damage. Like most engineered systems, maintenance of these boilers is required to improve the availability and safety of the plant. However, delays are common in the execution of these maintenance projects. This study explored factors contributing to delays and their effects on boiler maintenance during half station shut down in a coal-fired plant. The study adopted a qualitative approach using project documents and open-end questionnaires as a data source. The findings identified sixteen factors contributing to delays, and twelve effects thereof. Additionally, mitigation for dealing with contributing factors is also presented. The study results can assist practitioners working in boiler maintenance to adopt a proactive approach to manage delays and contributes to the global field of knowledge.