The current inventory had shrunk from 9500 rooms to about 9200 over the past two years.
Humphries said about 1300 rooms were under construction and should be in use by 2020.
However, a further 3000 rooms were needed in Auckland ensure future demand was met.
"There are a number of issues holding developers back, including high construction costs, the increasing level of difficulty in acquiring adequate development funding, challenges in securing suitable sites, and a general lack of sector experience and knowledge," Humphries said.
"In addition, the proposed 'targeted rate' proposed by Auckland mayor Phil Goff will almost certainly act as a deterrent for new developments moving forward."
Humphries said the growing presence of Airbnb may alleviate some of the supply issues in the short term.
"However, Airbnb alone will not be adequate to cater for demand over the medium to long term."