Construction Permit necessary in Fort Worth, TX?

[Nancy Wang]

I am buying an investment property in Fort Worth, TX. Once closed, I would like to add new walls to separate bigger empty areas into individual bedrooms. No windows changes are needed. Only need add walls/doors/closets. Also I will add a shower to downstairs half bath to convert it to a full bathroom. I am hiring a licensed plumber doing the whole job.

I called the City. City said permits are needed for above jobs. The contractors I have been talking to all said it is not necessary. I understand all the jobs are done inside so City won't discover it when the work is being conducted, but since I plan to hold this property as rental for a  while and eventually I will sell it. I am wondering anybody has any experiences and suggestions on what I should do now? Can I get by without pulling the permit? Without a permit, once the City found it out, what will be the consequences? How much time and money cost i have to add by pulling the permit? Do you guys investors always pull permit in a similar reno job? Thanks a lot.