The firefighter participants, who numbered 411 across the country's professional and volunteer brigades, in some cases climbed the tower using breathing apparatus - which also meant carrying 20kg of oxygen on their backs.
"It was challenging and hot," du Plessis-Allan said of the long climb up.
"I have massive respect for the firefighters. You get inside one of those suits and it's so hot. And all those other women [with slower times] were wearing steel in their boots and wearing their full kit … we [in Squad 31] have got it so easy."
Fellow Squad 31 member, New Zealand Breakers chief executive Matt Walsh recorded a time of 11m 37s while cancer survivor and funding campaigner David Downs did it in 19m 48s.
The fastest firefighter was Josh Harrison, with a time of 8m 17s, and the fastest female firefighter Helen Sinclair, at 13m 28s.
In the Firefighter of Steel category, where participants wear especially heavy gear, Mike Steenson finished in first place, at 13m 30s.
Du Plessis-Allan was taking part in her first stair challenge, after being encouraged by fellow participant and ZB broadcaster Ivanka Zonich, who completed the climb in 19m 10s.
Training was forgotten until about a month out from the event, when she began spending more time on the step machine at the gym and climbing the five flights of stairs in the NZME building where 10 reps equals the number of steps in the stair challenge.
Still, du Plessis-Allan wasn't sure how she'd go, and was amazed to climb the tower in just over 12 minutes.
"All I do is walk around an air-conditioned office all day."
Every day seven children and adults in New Zealand are diagnosed with a blood cancer such as leukaemia, lymphoma, myeloma or a related blood condition.
Funds raised through the stair challenge are used by Leukaemia & Blood Cancer New Zealand to help patients and their families through programmes, hospital visits and providing information, and supporting research into cures and better treatments.
