Foundation soil grading

When grading soil away from the foundation, what's the optimal distance between the bottom of the house sheathing and the soil?

As BG said 6" More if possible, especially if you live in snow country, and an outward slope of 5% for at least 2'

Don't forget about your crawlspace vents if you have a crawlspace. You don't want to cover them up or send dirt and water down the vent. I shoot for 2% grade away from the house for at least a good 10'. That's only like 3 inches so it is easy on the eyes and functional.

I have also heard that the minimum clearance is 2" from wood siding to concrete. Which jives with the 6" for soil.

International codes one and two family dwellings

Drainage the lot shal be graded so as to drain surface water away from the foundation walls
The grade away from the foundation walls shall fall a minimum 6" within the first 10 feet

height from wood siding 8" unless it is protected by concrete sheathing where the dept can be reduced to 4" providing rot resistant materials / siding is applied Example vinyl siding cement board or PVC material frost board Sorry the sections and sub sev ctions wer too long for me to type it all so I just highlighted the important language