I'm wondering if anybody knows a good source for buying XPS Rigid Foam Insulation in Southern California. It seems difficult to find. I am looking to insulate around the exterior of my foundation as well as under a new concrete slab which will have hydronic radiant heating. If I can afford it I would also use it for insulating the roof from the exterior as I want to retain the exposed beam and t&g ceiling. Thanks, Alexander

Best source in New England seems to be commercial roofing suppliers; don't know if they would use it in SCal, but worth a call.