Just had a new roof put on a 3 car garage- gable pitched roof. After every rain (last 2 rains were heavy) I sweep up say, a half dustpan full of the "sand'/gravel/whatever you call them. the shingles are 3 tab. Man, at this rate, will I have any left in a year?
It's normal that soon after new shingles are installed that a portion of the granules come off, & less during the remaining lifespan of the shingle. I'm not a full time roofer but I've installed dozens of roofs over the years & have seen it before. The transporting, the handling, & the installation loosens some of them, but there will be plenty remaining.
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