How Much Does Slate Roof Repair Cost?

Average Slate Roof Repair Costs

Slate roofs are popular largely because of their longevity and classic look. They can last up to 200 years, depending on a few factors, like hardness and composition. Other common roofing materials like clay and concrete last up to 50 years, while wood shingles can last 25 to 80 years, depending on the variety. However, even slate tiles require periodic maintenance and occasional repairs.

Synthetic vs. Natural Slate Roof Repair Cost

Slate roof repairs run twice what general roof repairs cost. But that depends on whether it’s real or synthetic. Synthetic tends to fall on the less expensive side, but only by about $2 per square foot. 

Synthetic

Synthetic slate costs $5 to $13 per square foot to repair. It’s usually made from composite materials such as plastics and rubber, meaning repairs often mean replacing a shingle or two. Consider replacing it if it's near the end of its lifespan, which varies based on the material. Synthetic slate is:

• Slightly less expensive to maintain than natural slate. 

• Slightly more impact resistant than stone, meaning you shouldn’t need to repair it as often.

• Better suited for lower angle roofs. 

Synthetic slate materials come in two different varieties. 

• Slate style asphalt shingle repair costs: $600–$1,600. Not a true slate look alike, but something of an alternative. It’s simply cut in a slate or shake style, but still looks like asphalt and lasts about 30 years.

• Composite and rubber slate style: $300–$1,000. Composite materials made from plastics and rubber, often with recycled materials, make up the majority of synthetic slate and last up to 80 years.

Natural

Repairs to natural slate roofs cost $5 to $15 per square foot, about $2 per square foot more than synthetic. Although installation of natural slate shingles costs far more than synthetic, repair costs remain close. Because of the long life of natural stone—up to 200 years—the other materials used with it need to last just as long. Typically, you’ll find only copper roofing nails, hooks, and flashing, though stainless steel is sometimes okay. 

• With proper maintenance, it should last four times as long as synthetics.

• Tend to delaminate and deteriorate faster on lower sloped roofs.

• Last longer than any other roofing material.

Types of Repairs

Maintenance and repair are usually sufficient for most slate roofs. However, slate roof popularity peaked in the 50 years prior to 1925, making many slate roofs along the eastern United States at least 100 years old, in many cases nearing their expected lifespans. Real slate roofs require a professional assessment to see if it needs repairs, maintenance, restoration, or a complete replacement. 

Get a field survey, which assesses:

• Broken or missing shingles

• Condition for delamination

• Condition of fasteners and underlayments

• Flashing and gutters

Replace Individual Slates

The cost of replacing a slate tile can range from $50 to $200, depending on the cost of local slate roof repair services and the specific procedure. For example, roofers may need to repair the surrounding fastenings when replacing a slate. They also commonly include sealing in a slate replacement.

Replacing individual slates is the most common and least expensive repair for a slate roof. A few cracked slate tiles may not cause leaks right away, but you still need to replace them to avoid more expensive repairs in the future. Hire a roofer with specific experience in slate tiles to inspect your roof and perform routine maintenance at regular intervals.

Replace Flashings and Fastening

The cost of replacing flashings ranges from $600 to $20,000, depending on the size of the roof repairs and the materials comprising the flashing. Replacing flashings is a common repair, although it’s more expensive than replacing slates. Natural slate roofs almost always use copper flashing, since it will last as long as the slate will.

Flashings are generally composed of some type of malleable metal such as the following:

• Copper

• Galvanized steel

• Lead

• Tin

Flashing materials also include combinations of these materials, including lead-coated copper or an alloy of tin and lead.

Flashings

The purpose of flashing is to prevent water from leaking through gaps in the primary roofing material, especially chimneys and vents. Flashing protects your home from the weather, working with the shingles wherever there is an angle that a shingle cannot fit. These areas include:

• Valleys

• Edges

• Chimneys

• Walls  

Flashing for natural slate is almost always copper, so it’ll last the lifetime of the roof. Synthetic materials might use standard flashing techniques used on asphalt roofs, but often use copper as well, for the authentic look.

Fastenings

Fastenings attach slate tiles to the roof. Fastenings are usually made of copper, steel, or galvanized steel. A slate roof doesn’t generally require replacement of the fasteners, provided it’s receiving regular, professional maintenance. However, excessive moisture can cause them to deteriorate.

• For natural slate, you’ll almost always use copper roofing nails since they’ll last as long as the slate. In some cases, you’ll also use copper hooks, but this is less common. Stainless steel nails and hooks can be used.

• For synthetic, you’ll use a typical galvanized roofing nail. They’re typically nails, but they can also be hooks. Some types of fastenings also require wire in addition to the primary fastener. Underlayment

Restoration

Restoration is the process of bringing an older stale roof up to like-new status. You’ll want to consider it for historical homes or restoration projects. However, restoration can mean either minor repairs or a complete replacement.

One exception is after a long period of neglect, which often occurs with historical buildings. In these cases, restoration may be better than individual repairs. Restoration is a comprehensive form of repair that involves the entire roof, rather than specific areas of damage.

A restoration can include any combination of repairs on a large scale. For example, it may involve the replacement of all fastenings and flashing. Most sources recommend complete replacement if over 20% to 30% of the roof needs replacing. 

Replacement

You’ll want to maintain your slate as long as you can, since new slate roof installation costs $15,000 on average, including both synthetic and natural. Natural slate costs $1,000 to $3,000 per square (per 100 square feet). A roof generally requires complete replacement once 20% to 30% of the slates have deteriorated beyond reasonable repair. 

A local slate roofer will need to perform an inspection for signs such as flaking tiles and powdering on the underside. A tile that produces a hollow sound when you tap it is also a sign that the slate is breaking down.

The following table compares the costs of replacing a roof with various types of roofing shingles, including slate:

Common Slate Roof Problems

Although slate looks beautiful, can last centuries, and cost more than most to install, it still comes with a few common issues you’ll want to watch out for. 

• Chipped or missing tiles: $50 to $200 per tile. A roofer can spot these from ground level. 

• Leaks: repair costs vary, but you’ll likely pay at least $500. Happens most often on older roofs with missing tiles.

• Hail damage: Costs the same as missing and chipped tiles and involves simply replacing each damaged tile. 

• Delamination: costs vary depending on the extent of the damage. It can mean a tile or two or a complete roof replacement. 

Slate Roof Maintenance Costs

Real slate roofs need regular maintenance, like any other. You’ll want to clean the gutters in the spring and the fall and replace any broken or missing slate. 

Every five years, get an inspection by an experienced slate professional. Roof inspections cost $120 to $300 but might be a little more for steep slopes. Make sure you hire a pro experienced in inspecting or working on slate. 

Cleaning

You’ll spend $0.30 to $1 per square foot for a low-pressure wash of your slate tiles. Cleaning your slate roof regularly can help maintain its appearance and structural integrity. The process generally consists of removing debris such as moss and fallen leaves. The roofer then washes the tiles with a gentle cleaning solution. The recommended cleaning frequency depends primarily on your climate, so you’ll need to consult with a roofer in your area.

Gutters

You’ll want to clean, maintain, and sometimes repair your gutters. With real slate, you’ll likely have copper gutters, but cleaning costs the same regardless of the material. 

• Gutter cleaning costs $160 on average.

• Copper gutter replacement costs $2,400 on average.

• Gutter repairs cost $375 on average.

Slate Roof Facts

The procedures for maintaining and repairing a slate roof are generally the same, but there are a few differences depending on the specific type of slate. Furthermore, there are several alternative materials to consider when a replacement is necessary. These materials can provide the look of slate, but are less expensive.

Real slate roofs weigh so much that you’ll need to reinforce the roof framing to support them. Synthetic weighs about half as much, which requires no extra reinforcement.

Different Types of Slate

All slate is made of stone, but its specific characteristics have a direct effect on how it will last. Hardness is the most important characteristic for durability, but so are mineral composition and impurities in the stone, which can cause delamination over time, shortening the lifespan. 

The specific composition of slate primarily depends on its origin, which includes New York, Vermont, Virginia, and Pennsylvania. Each quarried area has its own lifespan range. The types of slate fall into the general categories of hard and soft slate.

The following table shows the characteristics of slate tiles:

Alternatives

Alternatives to slate tiles range in cost from $3 to $8 per square foot, which is considerably cheaper than the real slate. These materials include ceramic and recycled rubber, among many other possibilities. They may last for up to 75 years.

However, these alternatives don’t match up to slate in terms of value, especially for historical buildings. In these cases, the value of the home may largely depend on whether it still has the original slate roof. Slate alternatives are therefore a better choice for a modern home that needs an upgraded look.

DIY Slate Roof Repair vs. Hiring a Pro

Slate is likely the worst choice of roofing material to DIY. Synthetic slate may be doable if you have roofing experience, but real stone requires experience. Without proper experience, you’ll likely overdrive or underdrive the nails, install the tiles incorrectly (which can lead to leaks), or crack tiles as you install higher up the roof. 

It’s almost always preferable to hire a professional slate roof installer for this job. And it’s important to hire a professional with specialized experience with slate, not just roofing in general. It’s not installed quite the same as any other material. 

Hiring a Slate Roofer

Always hire a professional with specific experience with installing slate roofing. There is no other material that goes on the same as slate tiles. There are also alternative options, hybrids that cut down on the install time, cost, and weight but with real slate. But those systems are specialized as well. It’s easy to crack the stone when installing it or put it in improperly, leading to leaks and damage later on that will require extensive repairs. 

You should be particularly cautious when hiring a roofing contractor to assess and service your slate roof. Not only should the roofers have years of general roofing experience, but they also need specific experience with slate tiles. Asphalt shingles may accidentally damage slate tiles, which is particularly undesirable when you own a house with historical value.

FAQs

What are the different types of slate roofs?

The types of slate roofs include standard, patterned, and random systems. 

• Standard: Same width, thickness, and length. They overlap in alternating rows and look uniform when fully installed. 

• Patterned: Use colored tiles and sometimes different shapes to create patterns.

• Random: Use random sizes and thicknesses to create a rustic look, much like wooden shake.

Are there alternatives to slate roofs?

The alternatives to slate roofs include fiber cement, concrete, and clay. They’re all less expensive and don’t last as long. But they provide hard, fire-resistant roofing. You can also choose rubber- or plastic-made composites that mimic slate. Be sure to discuss which is right for your home and budget with your pro before deciding. 

How do I pick a roofer to install a slate roof?

The training that professional roofers require varies by state, but they typically need to serve an apprenticeship of at least two years before applying for a roofing license. In addition, a roofer should also have liability insurance and a business license. Call the issuers of these credentials to ensure they’re valid.

Should I repair or replace my slate roof?

Repair a slate roof if it needs more than 20% to 30% of the tiles replaced. In most cases, this means that the roof may be nearing the end of its life and will likely continue to need rapid tile replacement. It’s better to just do it all at once. 

Is it OK to walk on a slate roof?

It is not OK to walk on slate roofing unless absolutely necessary. Many other types of roofing materials can withstand someone walking on them. However, walking on a slate roof can cause the tiles to crack, leading to expensive repairs. Only pros trained in slate tile installation and repair should walk on slate roofs.