My property is on two different levels, I am building two patios with steps leading to the two hights. The problem is the top patio will finish 600mm above the DPC of the lower extension. The extension extends out about 900mm for the main house so the top patio will run into the side wall. How would I finish this, at the moment there is a 400mm gap between the extension and original top patio. This drop is a potential risk to my kids falling down it. I have read about lead flashing being used chased into the brickwork, would this work or do I have to live with a gap. Any help and advise on how to finish this top patio with out causing damp issues.