On Fri, 5 Aug 2011 22:42:29 -0700, "azotic"
wrote:


A Minnesota state residential code says that new asphalt shingles cannot be
installed without first removing exist shingles, and on one section of the
roof Espey was installing new shingles over the old.

It varies by county. Jackson County is one where complete tearoffs
are required. It has to do with exposure to hail.

http://www.doli.state.mn.us/ccld/PDF/map_hail2.pdf