There are multiple claims that may be available to you depending on the promises and warranties made by your builder prior to purchase. I recommend reviewing your contracts and warranties with a real estate and/or construction defect attorney.
I agree with Katie, these are serious and costly problems to fix and you might need to sue the builder.
My name is Stephen R. Cohen and have practiced since 1974. I practice in Los Angeles and Orange County, CA. These answers do not create an attorney client relationship. My answers may offend I believe in telling the truth, I use common sense as well as the law. Other state's laws may differ.. There are a lot of really good attorneys on this site, I will do limited appearances which are preparation of court documents it is , less expensive. However generally I believe an attorney is better than none, but many will offer a free consultation and a face to face meeting generally will be better, I like my clients to write a short one page history of the fact and questions they have prior to meeting with them, so nothing is forgotten.