Slate shingle roof before repair. Photo: ŠJohn Leeke.   Not Recommended Losing Connections. Here, a slate shingle is missing. The joint of the two underlying shingles is exposed, letting water seep into the roof structure. Slates break when tree branches fall on them or when home owners or "tradespeople" walk on them. The metal nails holding the slates in place can corrode if they remain wet over the long term. If so, look for sources of moisture, such as leaks further up the roof or moisture buildup in the attic space. Slate shingle roof after repair. Photo: ŠJohn Leeke. Recommended Re-Connecting. This slate shingle has been replaced with one that matches the surrounding shingles. A copper sheet metal tab is nailed into the underlying joint and bent up and over the lower edge of the shingle. Wood, asphalt and metal shingles are replaced using other methods. Plan your work: Inspect the roof shingles with binoculars after major storms and at least once every year for loose, broken or missing shingles. Repair as soon as possible. Maintenance tip: Repair using methods, procedures and techniques that respect the original system. Match materials in type, size and quality. Build up a small stockpile of matching replacement shingles in advance from shingles that fall off the roof, architectural salvage companies, and building material suppliers.