How Can I Tell If My Slate Roof Needs Repair?

Posted on: 14 February 2015

Slate is a highly durable material that can last anywhere from 50 to 175 years, depending on the quality of the slate. Performing an annual inspection of your slate roof will help you decide when it's time to seek slate roof repair. To start your inspection, walk around the exterior of your home and use a pair of binoculars to examine the state of your roof. As you're inspecting the roof, look for these signs of damage and distress:

  • Deteriorating flashing. Flashing is often the first thing to go on a slate roof. Look for signs of rust and corrosion on the exposed flashing around vents, pipes and chimneys. 
  • Effervescence on the slates. Effervescence is a white, chalky substance that may appear on the exterior of slate shingles. Effervescence will start at the edge of the shingle and work its way inward until the entire shingle has turned white. 
  • Missing or broken slates. Because slate roofs often have no sheathing beneath the shingles, missing or broken shingles can be a particular problem. In some cases, missing shingles can open up a direct hole into the attic below. 
  • Slates are flaking and the edges are jagged. Slate will start to flake when it's beginning to deteriorate. Flaking will begin at the edges of the slate, resulting in a jagged perimeter around the exterior of each shingle. 

Once you've performed a visual inspection, go into the attic of your home to perform a tap inspection. Use your knuckles to rap on the underside of the exposed slate shingles. Slate that is in good condition will emit a clear, high ringing noise. Slate that is significantly deteriorated will emit a dull thud when tapped. 

Slate shingles deteriorate all the way through when they're at the end of their lifespan. This means that when you're in the attic, you'll be able to see as well as hear signs of shingle deterioration. The same signs of visual distress that were visible on the top of the shingles (effervescence and flaking) will  be visible on the underside of the shingles as well. 

If you've noticed that some of your shingles are showing signs of age, contact a roofing specialist immediately. Replacing broken and deteriorating shingles on an as-needed basis can prevent the need for a roof replacement later on. By performing this kind of annual maintenance, you can extend the life of your roof by many years.