A permanent solution was needed as the games seemed likely to continue.
He said the grandstand, built in 1962, was "old and tired" and initial investigations indicated it would not meet earthquake ratings for a roof platform.
Geotechnical assessments were needed to determine the rating, likely followed by remedial works before the platform could be built.
He said the games brought huge numbers of people into the city centre and greatly benefitted hospitality businesses.
SKY was not helping to fund the work, he said.
In the Mitre 10 Cup, the Bay of Plenty Steamers played at the Tauranga Domain twice last season and three times in the 2017 season.
This year's draw includes two Tauranga fixtures.