Wow! You've got yourself a friendly and cooperative Builder. I'll bet your friends are jealous. But even good builders make mistakes. This should be easy. It's my very own 12 step program.
1. Document all communications with your Builder.
2. Have the property inspected by a professional home inspector who will cite authoritative sources.
3. Compile your own list of defects not covered by the private home inspector.
4. Give both lists of defects to your Builder.
5. Have the Builder notify you in writing what repairs if any, will not be addressed and why.
6. Agree as to what constitutes and acceptable repair.
7. Determine who will be responsible for the costs of additional inspections if needed.
8. Have applicable warranties extended on repaired items.
9. Have the Builder provide you with a schedule of when the repairs will be started and completed.
10. Re-inspect as necessary and sign off on acceptable items.
11. Take your Builder to lunch and let him know that you'll be referring prospects to him. Then do it. They've earned it.
12. Enjoy and maintain your home.
If you've tried the tips above and aren't making any progress, jump to not-so-friendly builders.