When should the special inspector prepare a written report of inspection?

The correct answer is that the special inspector should prepare a written report of inspection after each inspection visit. This practice ensures that all observations, assessments, and any issues identified during the inspection are documented in a timely manner. Consistent reporting after each visit provides a comprehensive and precise record of compliance with applicable codes, standards, and specifications. This frequent documentation allows for immediate attention to any problems identified, facilitating prompt communication with the project team and contributing to the overall integrity of the construction process. Timely written reports are crucial for maintaining the quality assurance process and ensuring that all involved parties are kept informed of the project's status regarding compliance and quality standards.

The other options do not align with the standard practice for special inspectors, as waiting until the end of the project or providing reports only monthly or for nonconforming work could lead to missed opportunities for immediate corrective actions and could hinder effective communication and oversight throughout the duration of the project.