The glasses rattle when someone crosses the dining room, and the quote says 'reinforce floor'. Will that stop the bounce, repair damaged timber, or support the heavy cabinet you want to add? Blocking and sistering do different jobs. Start with the one you actually need.
Name the complaint first
Is the concern vibration, a split member, a new concentrated load, or tile cracking? Weyerhaeuser's floor-performance bulletin distinguishes performance enhancements such as blocking from measures that extend allowable spans. A floor can feel different without gaining the capacity someone assumes.
Ask for a repair that can be checked
A useful proposal identifies the existing members, attachment, bearing, extent of work, and any services in the way. Engineered joists need their own approved details. Do not assume a short extra board, a few screws, or tight blocks reproduce a designed sistering repair. Ask who accepts the completed work and what access they need.
Before the next step
- Describe the symptom and any planned new loads.
- Ask for the exact repair detail and its purpose.
- Coordinate inspection before the ceiling closes.
Ask the contractor to finish this sentence: 'This work is intended to fix...' You should recognize your actual problem in the answer. A heavy aquarium needs its own floor-load review.