Fire-testing data, such as charring rates and failure modes of structural elements exposed to ISO-standard fires, for unprotected cross-laminated timber (CLT) panels made of domestic timber were investigated to apply the reduced-cross-section method to CLT panels. For the charring rates, a series of fire tests without loading was conducted with experimental parameters including adhesive type, lamina thickness, and wood species. Based on the measured charring rates, a series of fire-resistance tests for loadbearing walls, floors, and roofs using unprotected CLT panels exposed to ISO-standard fires was conducted to investigate fire resistance in terms of loadbearing capacity, integrity, and insulation. Fire-resistance test for a CLT floor-wall-floor-wall structure with tension bolts and self-tapping screws was also tested to investigate the insulation and integrity of joints under loading. This paper summarizes the results of these tests.