Three people arrested in connection with the fire at the former Tolly Cobbold Brewery in Ipswich have been released under investigation.
Firefighters were called to the scene in Cliff Quay at 4.35pm on Sunday, February 23 and finally left at 7.14am on Monday morning.
A total of 27 engines were called to the blaze, according to Suffolk Fire and Rescue.
Fire crews remained at the scene overnight Sunday to monitor hot spots of heat which posed a continued fire risk.
The spokesman confirmed that a structural engineer inspected the site on Monday.
A 29-year-old male was arrested on suspicion of arson on Sunday and a 26-year-old man was also arrested on suspicion of arson on Monday.
A 44-year-old woman was arrested on suspicion of assisting an offender, also on Monday.
All three have all been released under investigation pending further enquiries.
The fire service spokesman said the fire had eventually spread to all floors above ground level, leaving six floors in all affected by the blaze, making a "significant impact" on the building.
Anyone who witnessed the incident or saw any suspicious activity at around the time of the fire should contact Ipswich police on 101, quoting crime reference 37/11543/20.
Alternatively, contact Crimestoppers anonymously on 0800 555 111.
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