I would like to close in my patio, by framing a wall with a french door. My concern is installing the bottom plate directing to the floor, it will allow water to accumulate at the bottom of the siding and against the bottom plate. Is it possible for me to pour a concrete ledge or anchor some form of concrete to build height from the slab to the bottom plate? I feel like a 4 to 6 inch concrete ledge would help to keep water away from the siding. My understanding is it’s difficult to get old concrete to bond to new concrete. What would you guys recommend?