Vertical hollow fired-clay brick masonry walls, commonly assembled with thin adhesive mortar, find widespread use in mid-rise building construction due to their advantages, including rapid construction, cost efficiency, precision, aesthetics, and cleaner worksites. This work investigates and analyses experimentally and theoretically the behaviour and the resistance of this kind of load-bearing masonry walls exposed to fire. Walls are built with vertical hollow bricks with a thickness of 20 cm, joined by thin-adhesive mortar. The exposed face is protected by a sandwiched coating constituted of stone wool and plasterboard. Through different tests, it is shown that the sandwiched coating panels adhere strongly on walls and act as a fire barrier. For the engineering application, this kind of wall structurally resists more than 1 h at very high loading levels, proven by experiments and numerical simulations. The simplified engineering method developed contributes for a quick estimation of fire resistance rate for this sandwich masonry walls.