Around 300mm for new construction (a foot in freedom units). Glass wool or styrofoam. Slightly less in older houses.

"styrofoam"

Nitpick / clarification: this is not 'EPS' which is what is commonly known in the US a styrofoam (although according to Wikipedia, the trademarked name 'Styrofoam' actually referes to XPS); so not the white grainy stuff e.g. some disposable coffee cups are made from. Modern insulation is done with PIR, PUR or XPS.