Flames took hold on the first floor of a commercial unit at the site on Brineton Street in Pleck, Walsall, on Saturday evening.
Crews from Walsall and Bloxwich fire stations along with a technical rescue team attended the scene. The fire was put out and crews left the scene at around 7.30am on Sunday.
An investigation is now under way into the how the fire started.
A tweet from West Midlands Fire Service during the incident said: "Crews from are in attendance at a four-pump fire on a trading estate in Pleck in Walsall. Currently tackling a severe fire on the ground floor."