How long is my Building Permit good for? Does it expire?

According to the Building Code, Building Permits expire in 6 months (180 days).  Work must commence within that period and continue without interruption. However, the permit may, with permission of the Building Department, be renewed for up to 6 months provided that the request to extend the permit is made prior to original expiration date and you can show that progress on the project is being made. After that, if you have not started or continuously worked on the project, your permit will be considered abandoned, and you will have to reapply.