If you reported the problem during the warranty period in the manner provided for in your agreement with the seller and can prove that the seller had been properly advised of the problem, then the seller should still be responsible for fixing the problem.
However, before taking any further action, I would suggest that you take your contract, and any related correspondence that you have with your seller and meet with a real estate attorney who can review the relevant document and facts with you. Many real estate attorneys offer free 30-60 minute consultations and you would be well-served to set up such a meeting ASAP.
Any answer or other information posted above is general in nature and is not intended, nor should it be construed, as legal advice. This posting does not create an attorney-client relationship between you and the posting attorney, and you are urged to engage a qualified attorney who is licensed to practice in the relevant jurisdiction.
Has the seller/builder told you "oops, you missed the 1-year period?" I would agree with Attorney Hansen that if you notified the warrantor in a timely, and contractually proper method, before the 1 year is up, that person is still on the hook. In addition to a potential claim for fraud, there may also be one for deceptive and unfair business practices. If the seller/builder is a licensed contractor, you may also want to file a complaint with the Contractor's State License Board.
I generally agree with my colleagues' answers, except that this may not be fraud. But it certainly would constitute a breach of warranty, especially if you have anything in writing showing you reported the problem. Even better would be something in writing from the seller acknowledging the problem.
Before you do anything, contact a real estate attorney to review the warranty and sales documents. Not doing so could result in your losing valuable rights.