I have a flat roof which bakes during the hot days here in So. Cal.
The insulation is poor and I would like to put a reflective coating on it.
Question is: It currently has small rocks on the surface, should I sweep these up and toss them ?
Obviously I cant paint over them but would appreciate any other tips.
Thanks

The gravel on the roof is there to protect the surface of the ashphalt. It reflects the rays of the sun and prevents the asphalt from cracking. If you want to put a reflective coating you need to scrape the stone into piles and then use a fibrated silver roof coating. Once its down spread the gravel back over it to offer more protection. If the gravel is is fairly good shape adding the silver coating will do little to drop the temps within the attic area.
The best thing you can do is increase the ventilation below the roof if at all possible. Of course this cannot be done if the ceiling is part of the roof structure. Side wall vents are often used to do this if you have the space.

Be certain that the coating you apply is compatible with the roofing surface material. If the stones are embedded into the top coat of the roof, it is likely to be coal tar or asphalt. If the stones are loose layed on top of a membrane, it could be a completely different type of material. Make sure of what you have before you apply a coating that could damage the roof.