
I am not familiar with a product called "SolarGuard". However, it is not uncommon for metal roofs, especially those with reasonable rigidity, to be installed over old shingles along with a quality roofing underlayment.
I have a contractor installing on top of a tlock shingled barn, a standing seam galvalume metal roof. He is putting down solarguard between the metal and the shingles with no purlins. Is this a common installation? It seems like the solar guard will prevent rubbing at least for a few years. He is using 1.5” screws on 3/4” solid board deck. It sounds like the installation clips to be used allow for expansion/contraction. Should I request he do something different? He says a tear off will be an additional 2700.00. Also, with a tear off he would use ice shield which I read does not breathe properly, although, it is an exposed board deck inside the loft. Please help! -J. J.