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How Much Does It Cost To Repair A Slate Roof?

Typical Range: $697 - $2,084

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On This Page:

  1. Types of Repairs
  2. Slate Roof Maintenance
  3. Other Slate Roof Facts

Considered the Rolls Royce of roofing materials, slate roofs are popular not only for their historical significance and dignified look, but also for their 100+ years of life, on average. In fact, depending on the type you install or that your home already has, it may actually last closer to 200 years, which extends much far beyond the average of 20 years for asphalt shingles. Indeed, when compared to any other major roofing material, including clay tile (50 years), metal (30-50 years), wood (15-25 years) and concrete (50 years), slate is not only on top when it comes to longevity, but far above the crowd. However, a long lifetime doesn’t necessarily mean that a slate roof is installed and then forgotten. Even the highest quality roof cannot last a century or more without proper repair and maintenance on your part.

The cost of repairing a slate roof can vary. Small repairs or replacing a single cracked shingle may cost as little as a few hundred dollars, whereas more involved cleaning and restoration may cost several thousand dollars. However, given the fact that the average slate roof costs at least five figures to install, even the steep price tags associated with maintenance and repairs may be worth the expenditure in terms of preservation and increasing your home’s value.

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National Average
$1,361
Typical Range
$697 - $2,084
Low End - High End
$300 - $4,500

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Cost data is based on actual project costs as reported by 457 HomeAdvisor members in .

Types of Repairs

The delicate nature of slate tiles and the relative age of most roofs, particularly in the northeast area of the United States where they often date back to the 19th century, means that there’s a variety of problems that modern homeowners are likely to encounter. Among the most common slate roof repairs, two are the most common according to professionals:

        • Replacing individual slates
        • Replacing the flashing and fastenings

Replacing Individual Slates

By far the most common and least expensive repairs for a slate roof, replacing individual slates that have broken or cracked is an important maintenance point. In many cases, roofs with one or two cracked or fallen tiles don’t leak, but failure to address these issues in a timely manner can lead to more expensive and expansive repairs.

Most slaters liken the failure to replace one or two broken slates until more need fixing to waiting to have a cavity filled until more teeth decay. Thus, you should initiate repairs as soon as possible and have a roofer experienced with slate installation and maintenance perform periodic checks on the structural health of the roof to catch small problems before they worsen.

To that end, depending on the type of roof on a home and the extent of the damage to the individual tiles and roofing area, the cost to replace or repair a slate tile varies. Costs can be as low as $40–$50 per slate or as high as $200, with labor and other factors such as sealing, and replacing or repairing nearby fastenings affecting the final price as well.

Replacing Worn Flashings and Fastening

Another common repair, though one that is much more detailed and expensive, is replacing or repairing the flashings and fastenings surrounding your slate roof. Considered the "weak link" of any roof design, flashings are made of some type of malleable metal, such as:

        • Lead-coated copper
        • Terne-coated (a combination of a tin and lead alloy) sheet iron
        • Lead sheet
        • Copper
        • Galvanized steel

These materials are all used to seal up the penetrations throughout the roof, including chimneys and vents.

Flashings

These materials don’t last nearly as long as the slate itself and generally need replacement several times throughout the life of the roof. In fact, depending on the material used, flashings may need replacement as often as every 15–20 years or as infrequently as every 70. The costs to replace flashings, which is a preferable method to sealing them because that’s merely a Band-Aid in most cases, ranges from as little as $600 up to $20,000 or more, depending on the size of the roof and the materials used for the new flashing.

Fastenings

Fastenings, on the other hand, are the components used to secure slate tiles onto a roof. They are usually nails, though there is a French method that uses hooks instead. Fastenings are usually made of the following materials:

        • Steel
        • Galvanized steel
        • Copper
        • Wire

A professionally installed and well-maintained slate roof generally doesn’t require fastener replacement. However, excess moisture may lead to a more rapid deterioration of these materials and necessitate their replacement at some point. Failure to recognize this problem and fix it can lead to rapid roof deterioration and complete slate loss.

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Restoration/Replacing

In most cases, the minor maintenance and repair jobs needed throughout the life of your slate roof will be sufficient enough to ensure that it lasts. However, in some cases, particularly with historical homes, insufficient maintenance over the years leads to deterioration and disrepair ahead of the lifetime of the roof itself. In these cases, choosing restoration, a more intense form of slate roof repair, may be warranted. In other cases, age or damage may lead you to make the tough decision about whether or not to completely replace your roof.

Restoring a Slate Roof: Slate roof restoration can involve any of the repairs mentioned above, though generally on a grander scale. In order to choose restoration, between 70%–80% of the roof itself should be viable, with minor replacements needed throughout rather than damage concentrated in one area. Complete replacement of flashings and some or all fastenings may also be included in a restoration project.

Replacing a Slate Roof: Replacement, on the other hand, needs to take place at some point in the life of all slate roofs, particularly those on older, historical houses. The rule of thumb among slaters is to push for replacement once 20–30% of the slate has deteriorated beyond reasonable repair. However, it might not be immediately obvious that a roof is deteriorating. Professionals need to test the roof itself, looking for signs such as flaking of the tiles, powdering on the underside of the roof or a general hollow sound when tapped, indicating that the core of the slate has begun to break down.

In comparison to other roofing materials, slate is much more expensive to replace, which leads many homeowners to balk at a complete replacement. However, in some cases, especially with historic properties, the value of your home is attached to the slate roof, making replacement the only real choice. Either way, it’s important to acknowledge that replacing a roof is no small job, and if you’re in a home with an older roof, you should begin to plan and save for such an expense.

For comparison's sake, here's a look at the relative cost of slate, which is significantly more per square (which equals 100 square feet) when compared to any other roofing material:

Material

Cost per Square

Average Cost to Replace a 2,000-square-foot Roof

Slate

$1,500

$30,000

Asphalt Shingle

$90

$1,800

Clay Tile

$900

$18,000

Metal

$350

$7,000

Wood

$400

$2,000

Concrete

$400

$2,000

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Slate Roof Maintenance

One of the most important steps homeowners with slate roofs can take is regular maintenance of that roof. This not only includes immediately addressing any problems, such as a cracked or fallen tiles, but also having your roof inspected annually by an experienced slater who can safely and effectively evaluate the roof's condition.

Scheduled Cleanings

Regular cleaning can help maintain the structural integrity and appearance of your roof. An experienced slate roof cleaner removes debris such as moss and fallen leaves from above and below the tiles before washing the roofing with a gentle cleaning solution. Because the frequency at which you need to clean your roof can vary depending on your local climate, it’s important to consult with a professional about how often this project needs to be performed.

Careful Treatment

It’s also important to remember that it’s never okay to walk on a slate roof, as doing so will cause the slate to crack and create an even bigger and more expensive problem. This is why, unlike other roofing materials, only professional, experienced roofers used to working with this material should perform these inspections.

Conscientious Hiring

Furthermore, you should be exceedingly cautious regarding which roofing professionals you allow to evaluate and service your slate roof. Even more so than negligence on your part, the biggest threat to the life of a slate roof is shoddy or inexperienced workmanship from roofers accustomed to working with asphalt and/or those who simply want to rip a slate roof down to put up their own (familiar) materials. Especially in historical homes, it’s important that you only allow experienced slaters to work on and advise about your roof, or you risk losing significant value and historical integrity.

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Other Slate Roof Facts

While the repairs and maintenance needed for slate roofs are pretty universal, there are a few peculiarities that you should note in regards to the type of slate used on your roof. In addition, when replacement is inevitable, you should also be aware of the options available in terms of slate alternatives. These modern materials, though still more expensive than asphalt and other roof types, provide the look of slate without the delicate, heavy and expensive reality of the real thing.

Different Types of Slate

Whether or not a roof needs repair can depend on a number of factors, including the type of slate used to make the roof and its relative characteristics. While all slate is made of stone, where that stone originates and its resulting composition affects its durability over time as a roofing material. There’s a number of different colors, shapes and even styles used on various roofs from any number of areas, including Vermont, Pennsylvania, Virginia and New York, but all of them fall into one of two broad categories:

Soft Slate

        • Also known as S2 or S3
        • Lifespan of 50–125 years
        • Usually black

Hard Slate

        • Also known as S1
        • Lifespan of 75–200 years
        • Usually colored (not black)

Slate Alternatives

One final point you may want to consider if you need to replace your slate roof is that getting the finished look of slate does not always mean paying for it. In the 21st century, a number of "alternatives" made of everything from recycled rubber to ceramic offer a less expensive option that may last up to 75 years. While not as costly, these materials are still pretty pricey, ranging from around $235–$600 per square.

Also, it's important to note that these alternatives are no replacement for real slate in terms of value and authenticity, especially in historical homes where the home's integrity is often linked to the original slate roof. Instead, they’re a great choice for modern homes looking for a more upgraded roofing look.

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