There are however some other areas such as poor percolation (for sewage discharge) which may mean that the site itself may never get planning permission in ROI and it is important to check this out before going too far. In NI, your planning approval will stipulate that you must also get effluent discharge consent separately if you do not already have it.
Your designer, if they are a local, should also have a good understanding and plenty of experience in what the planners are looking for and the things that they tend to reject. This local knowledge can be invaluable. It can also be desirable to get a designer who is not afraid to challenge the planners when appropriate.
Some projects do not require planning permission, such as small extensions if they fall within specific parameters.
In the case of listed buildings, depending on the classification of the listing, you need to secure permission on some internal work too. If in any doubt you can request clarification from the planners whether your project does or doesn’t fall within planning law. The rules are complex. In NI, for example some can contradict or be superseded by others – so get expert advice. Permission for carrying out works to historic buildings in NI is controlled by HED (Historic Environment Division) and requires an application in addition to your planning application.
For new structures in ROI the rule of thumb tends to be is that if it is to be habitable, it requires planning permission.