I believe it's 4". I like it as I've had more than one hot water heater leak or explode out here. This keeps the water out of the house and from causing water damage/mold issues. PLUS, it gives me 4" of lift space. I'll have 12'4" on the shop side.
The framer was out chalking the lines this AM.
He's been framing for my GC and his dad before him for a long time. I hear good things from so I'm hopeful.