Hi Tan, I am doing something similar myself at the moment. I went though the planning process myself and selected a builder. There are couple of threads here on this topic too (do a search under "engineer costs"). Before starting the build I had to select an engineer (required by the bank & builder) to check stages and issue a cert of compliance. The stage payments cost approx €1000 plus VAT and approx €350 for the Cert of Compliance. I presume you are going with a contract build as opposed to Direct Labour? If you are happy with your builder (references checked out etc) then they shouldn't need much supervision. Your engineer will check each stage and if you (or your builder) have any doubts at any point then organise an additional visit (and charge!) but if the builder is reputable and the building is bonded with Homebond you should not need too many (if any) extra visits. Certainly, if you have a relatively straight forward house plan, you should be able to work through things like rads and plug points between yourself and the builder. Good luck with it.