A portable device for measuring deflection of a surface, comprising an elongate frame having a first end and a second end and a first datum surface, a first removable reference assembly adjacent the first end, a second removable reference adjacent the second end, a deflection gauge attached to the elongate frame between the first removable reference assembly and the second removable reference assembly, and wherein the deflection gauge engages and measures a deflection of the surface relative to the first removable reference assembly and the second removable reference assembly.