California Gardening: Replacing our lawn with DG in SoCal, 1 by aheim

aheim wrote:
We are replacing our front and back yards of about 2000 sq. ft. of misc. grass and weeds with decomposed granite. The workers mechanically removed the grass and tilled what was left. They just left, and we are seeing lots of roots still in the soil. We intend to put about 2 -3 inches of DG on top combined with large pavers, cacti, succulents and dymondia in some areas for ground cover. Our property is completely flat with no erosion issues at all. The big QUESTION IS... How to keep the grass from comming back?
We had thought of using "Layout Board" (a thin non-corregated cardboard used in the film industry to protect floors when setting up sets and shots in sensitive locations) instead of weed barrier fabric. We've heard that weed barriers sterilize the soil underneath, which is not our intent in the slightest. The layout board will theorecically stifle the weeds in the interim, and then decompose over time while allowing water to drain into the water table while the DG gets stable. Any thoughts?...