I have a hard time believing parts of the IRC as well. Especially the basement wall stuff. I wouldn’t sleep at night using that or our state amendment basement wall stuff, and now this ICF stuff. The walls are experiencing the same wind, seismic, or soil loads whether they are in commercial construction or not. To me you are just living inside the factor or safety more if you follow the IRC, then designing by IBC. Pretty hard to do when it’s your own license. I don’t do too much stuff without calculation, it’s too hard to trust a table over calculation. Be sure to get your fingers in a bucket of ice, you don’t want them to be sore tomorrow.