| 摘要 |
PROBLEM TO BE SOLVED: To finish a ceiling simply with excellent appearance without damaging a ceiling board at the time of the assembly execution of the ceiling board in the ceiling board by a tongue and groove joint. SOLUTION: In the ceiling board (a), a surface decorative sheet 4 is stuck on a rear muntin frame 3 formed of left-right muntins 1 and horizontal muntins 2, with which both muntins 1 are joined, a recessed groove 5 is recessed sideways to one muntin 1, and a projecting section 6 as an object to be fitted into the recessed groove 5 is projected sideways from the other muntin 1, and both end faces of the surface decorative sheet 4 are conformed to the surface-side end face of the recessed groove 5 and the surface-side end face of the projecting section 6 respectively. The rear-side end face of the recessed groove 5 is disposed on the same vertical surface as a surface-side end face, and the surface- side end face of the projecting section 6 is retreated and formed in size, in which a joint line is formed to a section inner than the rear-side end face at that time. |
