THE BEST SIDE OF CALCIUM SILICATE

Joints of duct programs shall be made substantially airtight by the use of tapes, mastics, liquid sealants, gasketing or other approved closure programs. Closure units employed with rigid fibrous glass ducts shall adjust to UL181A and shall be marked181A-P for pressure-delicate tape, 181A-M for mastic or 181 A-H for warmth-sensitive tape. Closure s