1. Look and log
Write down the symptoms, limit additional damage if it’s safe, and collect any background on prior work.
2. Evaluate the house and site
Flashing details, sill condition, frame material, glass performance, and trim finish work together — and count for as much as the window itself.
3. Nail down a written scope
Preparation, protection, materials, access, permits, testing, cleanup, finish work, exclusions, and change-order rules all belong in writing.
4. Line the proposals up
Verify credentials and weigh the reasoning and scope boundaries in each proposal, not just what it adds up to.
5. Wrap-up checklist
Confirm testing results, cleanup, documentation, warranty coverage, and any remaining maintenance duties.