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To run shower head pipe from the shower valve through 4″ high concrete block exterior wall I had to break out a course about 8 feet horizontally. All the vermiculite insulation drained out of the cavities (about 4 trash bags). After the plumber installs the pipe what is the best way to reinsulate the drained cavities and the pipe before I plug up the hole with block sections and mortar? The shower wall will be tiled over in travertine or ceramic over the block. I have 10-15 3 foot block cavities to fill. I thought about an expanding foam (Great Stuff, or similar) but it would take a lot ( I estimate 6 cubic feet of cavity combined total.