Choice are happy to answer your general questions on planning issues but when it comes to specifics you must ask the experts. Either the town planners or your architect or the person drawing your plans.
Remember: Rules and regulations change often! Never take anything for granted as mistakes can be very costly.
When it comes to planning this is where you need to start.
The Cardiff City Planning Office
This is located as follows.
Contrary to popular belief they are there to help you!. Ask them anything you like. Remember, ask first and get the answer in writing. Make sure you never put yourself in the position of having to apply for retrospective planning.