“High nails” were found on this roof. During roof underlayment installation it’s easy for installers to forget about proper pressure setting on their nail guns. In most cases too many nailers are hooked up to a low volume compressor and the air supply is not sufficient to drive each fastener fully. At time of installation only the severe “high nails” are noticeable. When the modified membrane seals to itself a tight bond is formed. “High nails” begin to protrude through the top surface of membrane causing rust and seepage.