Foundation safety factor for overturning and sliding?

[StructureMan44]

Other than the 1.5 safety factor for retaining walls in IBC 1807.2.3, is there anywhere else in IBC or ASCE 7 that states an provides additional necessary safety factor for overturning and sliding, specifically for mat foundations? My prior employer used a safety factor of 3 when checking mat foundation overturning and sliding and a safety factor of 2 when using dead loads adjusted downward for vertical seismic effects (1-0.2*SDS). The strength design load combinations (6 & 7) in ASCE 7 that likely govern overturning and sliding seem to have safety factor built in; a 0.9 dead load (possibly because we over estimate dead load?) and no contribution from live, snow, etc.

 

[SteelPE]

The strength design load combinations (6 & 7) in ASCE 7 that likely govern overturning and sliding seem to have safety factor built in; a 0.9 dead load (possibly because we over estimate dead load?) and no contribution from live, snow, etc.

Bingo.... This has been talked about extensively on this website.