Fire crews from Bingley and Shipley were called to the house on Nab Lane just before 2.30am today (Frid March 30) to deal with the blaze in the ground floor sauna room.
Four adults had got out of the house when fire crews from Bingley and Shipley fire stations arrived.
A West Yorkshire Fire Service spokesman said firefighters extinguished the blaze using four breathing apparatus and two hose reels.
The spokesman added: "Four adults were treated at scene for smoke inhalation. Smoke detectors were working in this property."