All Australian Heritage sash windows (Victorian,Federation.Art Deco etc) have been built will fine precise joinery ,cedar frames and quality Australian hardwoods for sills. These windows can be seen all over Sydney’s inner west, lower north shore If ,however your timber windows and sills were made cheaply and mass produced from the 60-70s on-wards, the majority of these window sills have been poorly constructed with inferior materials such as Maple and poor quality Cedar. This is not a good solution for a window sill and once they begin to rot,