Is there an OSHA regulation governing how many pallets can be stacked on top of each other in a warehouse setting?

There is no specific OSHA regulation for storing pallets. For general industry employers, OSHA can cite using 29 CFR 1910.176(b) when storage is unsafe. This standard is general in nature and does not address specific materials. It requires that stored materials must not create a hazard. Stored materials must be stable and secure against sliding or collapsing. However, an OSHA inspector can also turn to the General Duty Clause (section 5(a)(1) of the OSH Act) to cite an employer for an unsafe condition that creates a serious hazard, but no safety or health standard exists. Under this provision, you have a responsibility to provide “a place of employment which is free from recognized hazards that are causing or are likely to cause death or serious physical harm to his employees.”