Firstly, let’s establish the era of your Double Hung Sash Windows.
Are they Art Deco 1920s? Federation style or Victorian or Colonial?
Okay... let’s make it easier... most sash windows in the Sydney area pre 1950 are Counterbalance Double Hung Sash Windows with a rope and pulley system. If you have these windows they are made of quality joinery and cedar frames and hardwood sills.
Before colonization the native Australian red cedar was abundant and in huge stands, their preferred habitat was subtropical forests and river valleys this special timber the aboriginals used their trunks to carve tradition markings for directions on as they were easily carved
From the moment of colonization in NSW these trees were well sought out and were a wonderful resource, and quickly became the go to timber to be used in household furnishings and doors trims and double hung sash windows. The young trees were pink, the more mature and stronger timbers were dark red to almost black sometimes
Do you have traditional double hung timber sash cord windows? If so, they are well worth restoring. These windows were lovingly crafted with joinery hewn from all Australian timbers and built from the 1880s till the late 1960s, classical icons of Heritage Victorian Federation Art Deco style homes are found in abundance from Sydney’s inner city, lower north shore, and inner west, eastern suburbs, south Sydney, northern beaches and beyond.