"Our block backs onto Garigal National Park. Does that actually make a difference to how often we need a clean?"
Yes, and it's worth planning around rather than finding out the hard way. Garigal runs along both sides of Forestville, so a lot of blocks here have taller eucalypts and natives either on the property or right over the back fence on the reserve. More canopy over a roof means more leaf and bark landing in the gutters between cleans, especially with the rainfall Forestville gets, which is among the higher end for Sydney, shared with Frenchs Forest, Belrose and Terrey Hills. For a block like this, I'd give the same advice as anywhere backing onto bush: somewhere between six months and a year, depending on the number and species of trees around the property, with jacarandas in particular pushing that frequency up.



