Guinness parent company Diageo PLC said the fire started while a construction worker used a blow torch to repair the felt-lined roof of the unoccupied building, one of dozens on the sprawling brewery site. The building stored empty containers and machinery, not beer.
Dublin's fire department said it took 15 units more than three hours to bring the flames under control. Two firefighters were in stable condition at the nearby St. James' Hospital after inhaling what colleagues suspected was ammonia gas.
The fire sent billowing black smoke over the Dublin skyline and forced authorities to suspend services at a light-rail line that passes the Guinness complex.
But Diageo said brewing operations and tours at the brewery's tourist center - the most popular attraction in Dublin - continued in other buildings a half-mile away while firefighters battled the blaze.
Guinness brews its flagship dark-brown stout, as well as lagers Carlsberg and Budweiser, at the brewery in west Dublin. The company recently celebrated its 250th anniversary of continuous operations at the site.
Earlier this year, Diageo put on hold its 2008 plans to spend $1.2 billion in a radical shake up of its brewing operations in Ireland. Half of the Guinness site in Dublin, including the area affected by Monday's fire, would have been sold for property development. That idea had to be shelved as Ireland fell into deep recession and its property market plummeted over the past year.