I have read most of the postings on this forum...I have two questions regarding my planned project. First I will give you a bit of a description. I would like to build a flagstone patio off the edge of our driveway. The shape will be that of a wedge of pie where each of the straight edges (radii) on the wedge are about 25Â. It is about a 45 degree wedge, so the patio will be about 250 sq ft.

The tip of the wedge will be level with the driveway and there is 18" of drop from the point of the wedge along one 25Â edge of the pie slice and nearly no drop along the other edge.

Thus I need a small retaining wall along one side and along the curved edge of my pie slice. My intention is to build a dry stack wall and back fill behind it to attain a level patio.

My questions are: As this is a retaining wall, is there any reason I canÂt use broken concrete for the non-visible portions of the wall, those behind the face stones? IÂm thinking I can save a couple of bucks here. I understand the need for a gravel footer etc.

Second, the existing area is lawn, though very compacted and generally not what one could call a healthy lawn, there is grass. I understand that I need a given depth of gravel followed by sand to provide a proper base for the patio so I will have to remove sod from much of the area and back fill with gravel just to attain an appropriate base for my flagstone. However in the remaining area, can I leave the sod and back fill on top of the lawn? Anything to save digging out sod!

Thanks in advance for you advice!