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Michigan Administrative Code
Department - Labor and Economic OpportunityMIOSHAGeneral Industry and Construction Safety and Occupational Health StandardsConstruction Safety and Health Standard
Part 2 - MASONRY WALL BRACING
Section R. 408.40210 - Intermediate period requirements

Mich. Admin. Code R. 408.40210

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Current through Vol. 24-22, December 15, 2024
Section R. 408.40210 - Intermediate period requirements

Rule 210.

(1) When the height of an unbraced masonry wall exceeds the maximum height as shown in table 2 during the intermediate period, the masonry wall shall be braced on both sides.
(2) No one shall be within the restricted zone of a masonry wall subjected to winds exceeding 35 miles per hour during the intermediate period.
(3) When bracing cannot be installed because of work operations, no one shall be permitted within the restricted zone when the wind is more than 20 miles per hour during the intermediate period as shown in table 3.

TABLE 1

INITIAL PERIOD (LESS THAN 24 HOURS)

Maximum Unbraced Height of Unreinforced Masonry

Above its Base or Highest Line of Bracing for Resisting 20 mph Wind

Nominal Thickness Unit Weight of Masonry
Light Weight(1) (<105 pcf) Medium Weight(2) (105 to <125pcf) Normal Weight(3) ([GREATER THAN EQUAL TO]125 pcf)
Maximum Height Maximum Height Maximum Height
4" 8'-0" 8'-0" 8'-0"
6" 8'-0" 8'-0" 8'-0"
8" 9'-4" 10'-0" 12'-0"
10" 13'-4" 14'-8" 17-4"
12" 18'-0" 20'-0" 24'-0"

TABLE 2(5)

INTERMEDIATE PERIOD (GREATER THAN 24 HOURS)

Maximum Unbraced Height of Unreinforced Masonry

Above its Base or Highest Line of Bracing for Resisting 35 mph Wind

Nominal Thickness Unit Weight of Masonry Unbonded Masonry(4)
Light Weight(1) (<105 pcf) Medium Weight(2) (105 to <125pcf) Normal Weight(3) ([GREATER THAN EQUAL TO]125 pcf)
Maximum Height Maximum Height Maximum Height Maximum Height
4" 8'-0" 8'-0" 8'-0" 8'-0"
6" 8'-0" 8'-0" 8'-0" 8'-0"
8" 8'-0" 8'-0" 8'-0" 8'-0"
10" 8'-0" 8'-0" 8'-8" 8'-0"
12" 9'-4" 10'-0" 10'-8" 8'-0"

TABLE 3(5)

INTERMEDIATE PERIOD (GREATER THAN 24 HOURS)

Maximum Unbraced Height of Unreinforced Masonry

Above its Base or Highest Line of Bracing for Resisting 20 mnh Wind

Nominal Thickness Unit Weight of Masonry Unbonded Masonry(4)
Light Weight(1) (<105 pcf) Medium Weight(2) (105 to <125pcf) Normal Weight(3) ([GREATER THAN EQUAL TO]125 pcf)
Maximum Height Maximum Height Maximum Height Maximum Height
4" 8'-0" 8'-0" 8'-0" 8'-0"
6" 9'-4" 10'-0" 10'-8" 8'-0"
8" 14'-8" 15'-4" 16'-8" 9'-4"
10" 18'-8" 20'-0" 22'-0" 13'-4"
12" 23'-4" 25'-4" 28'-0" 18'-0"

(1) Light Weight Units at 95 pounds per cubic foot (pcf) unit weight.
(2) Medium Weight Units at 105 pounds per cubic foot (pcf) unit weight.
(3) Normal Weight Units at 125 pounds per cubic foot (pcf) unit weight.
(4) Flashing or other
(5) Tables 2 mid 3 are based on Type N masonry cement mortar.

Mich. Admin. Code R. 408.40210

1989 AACS; 2010 AACS