An addition or extension, refers to the process of adding an extra room or rooms to your house at either ground level or on top of your existing house. It could also include building under your home, say if it’s on the side of a hill and open underneath.
Renovation is a broad term that refers to home building improvements ranging in scope from small one room upgrades to larger scale whole house remodeling. Major renovations often include both room additions and alterations to existing structures.
Alterations refer to the changes to walls and rooms and their purpose within an existing structure. Say if you want to create a combined kitchen and living space that opens onto your landscaped back yard or to keep an eye on your kids while they play in the yard or, to relocate your living area to the north side of the home to improve your winter warmth. Generally alterations are without significant changes the outside walls or roofline.
There are a lot of older houses in Sydney that are just not energy efficient and have layouts and services that no longer serve the needs of modern families so a choice for home owners today is to knock down their existing home and rebuild a new one to suit their current and future needs instead of renovating. This can sometimes be more cost effective and faster than renovating.