Baltimore experiences an average of 30 freeze-thaw cycles each winter. Water penetrates tiny gaps in flashing or underlayment, freezes overnight, expands, and creates larger openings. By spring, those openings allow wind-driven rain to reach the decking. Natural slate roof tiles and composite slate roofing both resist the freeze-thaw damage that destroys asphalt shingles, but only if the underlayment and flashing are detailed correctly. Cheap installations that skip the proper ice and water shield placement or use aluminum flashing instead of copper fail within a decade. The slate tiles survive, but the system underneath them does not. That is why structural prep and flashing quality matter more than tile selection for long-term performance in this climate.
Baltimore's historic neighborhoods contain some of the finest examples of slate roofing in the Mid-Atlantic. The original installations from the 1920s and 1930s used Pennsylvania black slate and copper flashing. Many of those roofs are still functional today because the craftsmanship was excellent. Modern installations must meet that same standard to achieve comparable longevity. A Plus Roofing Baltimore understands the architectural context and structural requirements of these older homes. We work with the same attention to detail that the original builders used, adapted for modern building codes and material science. When you choose slate for a Baltimore property, you are making a multi-generational investment. We treat it that way.
