Design No. U901
Bearing Wall Rating - 4 HR.
Nonbearing Wall Rating - 4 HR.
- Concrete Blocks* - Various designs. Classificaon B-4 (4 hr).
- Mortar - Blocks laid in full bed of mortar, nom. 3/8 in. thick,
of not less than 2-1/4 and not more than 3-1/2 parts of clean sharp
sand to 1 part Portland cement (proportioned by volume) and not more
than 50 percent hydrated lime (by cement volume). Vertical joints staggered.
- Portland Cement Stucco or Gypsum Plaster - If used, add 1/2
hr. to Classification.
- Loose Masonry Fill - If all core spaces are filled with loose
dry expanded slag, burned clay or shale (rotary kiln process), water
repellant vermiculite masonry fill insulation, or silicone treated perlite
loose fill insulation, Class D-2 (2 hr) or C-3 (3 hr) concrete blocks
will provide a 4 hr fire resistance rating.
*Bearing the UL Classification Marking
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