I inspected a 1982 home with the original Spanish style concrete tile roof and there was no felt paper, just some foil insulation board for sheathing. I don't see these types of roofs much. I seem to remember that you can use this type of roofing with no underlayment if it is greater than 4 in 12. However, the tiles are no longer mostly decorative installed this way and are far more likely to leak with cracked tiles. I believe the standard now is to have underlayment, but do not believe it was required here when this home was built. I have certainly never seen this type of foil backed board used for sheathing. I could not tell if there were any slats or if the tiles were just fastened to the 16OC rafters. Any enlightenment would be appreciated.

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