Hampshire Fire and Rescue Service said the building was well alight when the fire crews arrived on the scene and two neighbouring houses were evacuated as a precaution. No-one was injured in the fire.
Fire crews remained at the scene over the weekend. The fire service confirmed that an investigation would be carried out to determine the cause of the fire. Hampshire Police said the fire is not being considered suspicious.
Adept Linen and Garment Rental provides laundry services to clients throughout the home counties. No-one at the company was available to comment.