Saddle Manholes Saddle Manholes CivilG (Civil/Environmental) (OP) 20 Feb 18 15:49 Could someone please tell me what a saddle manhole is and why are they used in place of regular manholes? Thanks, CivilG RE: Saddle Manholes jgailla (Geotechnical) 20 Feb 18 17:10 A saddle or doghouse manhole is used when you want to place a sewer junction box without disturbing the existing flow for a long period of time. The manhole without a bottom and a notch for the pipe is installed over an existing pipe. The new pipes are hooked into the manhole. Then the base is poured in place and the existing pipe cut.