frost depth additonal depth?

[delagina]

I don't normally have projects in the north.
is there anything I should add to this frost depth?
say most cities in Arkansas, it's only 10" below of footing right?

 

[BigH]

I love all these maps - but for frost to "attack" a foundation it needs 1) water, 2) the right type of Soil and 3) temperature(climate such as barren or snow covered). If one has, as I did once in Northern Ontario where 9 to 10 ft would have been the "normal" depth (2.7 to 3.0 m) we put the footings down about 24 inches or so (exact depth is lost in a greyer part of my mind). Why? The depth of the founding soil was extensive clean sand (non frost susceptible); the water table was down 12 ft. It didn't make sense to go down 9 ft in this case. By the way it matched existing foundations - an industrial plant.

 

[bridgebuster]

I agree with Mike, contact the local building department unless you have a geotech familiar with the area. Last year I had a project involving replacement of pipe support foundations in central Pennsylvania that failed due to frost heave. Most maps show the frost depth for that region as 36"; the supports we replaced were constructed at 48"; our geotech said use 60" minimum (so far so good).