I use the 2% Cal-OSHA requirement per section 1717(a)(4) below.
Brent Koch, P.E.
Koch Engineering, Inc.
Subchapter 4. Construction Safety Orders
Article 29. Erection and Construction
?1717. Falsework and Vertical Shoring.
(a) Design Loads.
(1) Formwork and falsework or shoring for the support of concrete or other
materials shall be designed, erected, supported, braced and maintained so as
to assure its ability to safely withstand all intended loads during
erection, construction, usage and removal.
(2) The minimum total design load for any formwork and shoring shall be not
less than 100 pounds per square foot for the combined live and dead load
regardless of slab thickness; however, the minimum allowance for live load
and formwork shall be not less than 20 pounds per square foot in addition to
the weight of the concrete.
When the equipment listed below is used, the above figures shall be
increased in all cases by the amounts shown.
Worker propelled carts.... 10 pounds per square foot.
Motorized carts........... 25 pounds per square foot.
(3) Special consideration shall be given and the necessary additional
allowances made for any unusual circumstances such as floor hoppers,
concentrated piles of reinforcing steel bars, or similar loads.
(4) The lateral loads for shoring to be resisted at each floor in both
directions by diagonal bracing, or other means, shall be taken at not less
than 100 pounds per lineal foot of floor edge or two percent of the total
dead load whichever is greater.