The fastest horizontal chimney ascent over 10 m is 17.176 seconds and was set by Raffael Armbruster (Germany) at Halbmondgaesschen in Cologne, Germany, on 10 June 2013. The feat was recorded for the TV show GUINNESS WORLD RECORDS - Wir holen den Rekord nach Deutschland, aired on RTL2 (Germany).
The street Halbmondgaesschen is very narrow, marked by two houses facing wall to wall. Raffeal climbed while being 'squeezed' between the walls with stretched out legs and arms, holding his weight only by pressing against the walls.
Comments below may relate to previous holders of this record.