1. Document before anything else
Capture the symptom, timing, and history, and take basic precautions if safety is a concern.
2. Evaluate the mechanical system
Equipment age, duct leakage, airflow balance, humidity control, insulation, electrical capacity, and room-by-room comfort should all be part of this evaluation.
3. Nail down a written scope
Preparation, protection, materials, access, permits, testing, cleanup, restoration, exclusions, and the change-order process belong in writing.
4. Compare providers on more than price
Verify credentials, then weigh the reasoning behind each proposal against the others.
5. Walk through closeout
Confirm testing, cleanup, documentation, warranty terms, and whatever maintenance is left to the homeowner.