write to the ontario house garanty association. I am not sure what it is called in ONtario, but in QC, it is the APCHQ. You should write to them soon, or they can say that you didn't advise the builder within a limited time frame and your garanty wouldn't apply.
我的房子在QC,我是应该同时联系APCHQ和builder呢,还是有什么流程呢?