how much c4 for stone wall?

Updated: [Rust] Using C4 on Walls (Wood, Stone, Metal & Armored)

As the title says, I am aware it takes 2 C4 to destroy a stone wall, but what if the wall is around the wrong way, so you’re putting the C4 on the inside of the wall compared to the outside?

Rust Raiding Economics – Stone walls and building blocks