Christchurch police said Michael Croucher went missing hours before his Tilford St home was engulfed in flames last Thursday.
Croucher's father, Glen, reached out to him on Facebook: "Just knock on the door we will help sort things out with you, love you, dad".
Police said the 40-year-old Croucher was still missing and asked anyone who has seen him to come forward.
Croucher was last seen by a neighbour at his home in Tilford St, Woolston, at about 5pm last Wednesday.
Police haven't found any evidence to suggest Croucher was caught up or injured in the fire.
Croucher was an avid cyclist and was known to use a selection of three bikes in and around Woolston.