Fastener selection is a small but critical detail that a professional metal-roof-contractor never overlooks. In exposed fastener systems, the screws must have high-quality EPDM washers that seal out moisture. A meticulous metal-roof-contractor will also ensure the screws are driven at the correct angle and depth. Over-tightening can crush the washer, while under-tightening leaves a ga... https://kkroofspecialist.com.sg/metal-roof-contractor/