Is There Such a Word as Sprinklered?

having or protected by a sprinkler system.

Is it sprinklered or sprinkled?

sprinkled is the past tense of the verb to sprinkle, which (as you guessed correctly) has a different meaning: If the building is sprinkled, the sprinkler systems were already activated & everything is wet.

What does sprinklered mean?

: having a sprinkler system.