I'm making some large planter boxes to attach to the house under the windows (82" wide).
I would like to attach them using a French cleat to make the boxes easily removable for cleanout / refinishing.
I'm thinking of ripping the cleats to match the angle of the siding, so the boxes sit plumb against the wall. I'm concerned about water penetrating the screw holes and rotting the sheathing, since I can't put a piece of flashing over the top of a French cleat . The lap siding is fiber cement.
Does anyone have any suggestions to mount these boxes? They will be pretty heavy, since they are made of PT 2x10, with decorative cedar panels attached to the 3 show sides, in addition to the weight of the dirt and plants. Thank you for any advice.