Our 65mm downpipe is available in 3 different lengths in most colours, these are 2.5m, 4m and 5.5m. Square downpipe is usually used in conjunction with square and sometimes ogee gutter systems. 2.5m lengths are usually sufficient for rainwater pipe drops on single storey buildings, 4m and 5.5m lengths are generally used for buildings of two storeys and above. Rainwater pipes are always a pushfit joint - never use silicon or solvent weld on these systems as there might be a requirement to take them apart for cleaning or unblocking at some point in the future.