The average cost to repair a slate roof is about $1,560, with a range between $706 and $2,487. Small repairs like replacing individual shingles may cost as little as $250, but restoring a major portion can cost up to $5,000. A new slate roof costs over $10,000 to install, so even major repairs are usually worthwhile.

On This Page:

1. Slate Roof Repair Costs
2. Types of Repairs
3. Slate Roof Maintenance
4. Slate Roof Facts
5. FAQs

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 the specific type. Other common roofing materials like clay and concrete last up to 50 years, while wood shingles can last 15 to 25 years. However, even slate tiles require periodic maintenance and occasional repairs.

Types of Repairs

Slate tiles resist weathering extremely well, but they can break easily if you walk on them. They’re most common in the northeastern United States, where many slate roofs date to the 19^th century. Here are a few common repairs that homeowners should watch out for while maintaining their roofs:

• Replace individual slates
• Replace flashings and fastenings
• Restoration

Replace Individual Slates

The cost of replacing a slate tile can range from $40 to $200, depending on the cost of local roofers 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. 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 and the materials comprising the flashing. Replacing flashings is a common repair, although it’s more expensive than replacing slates. 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. Replacing flashing is usually preferable to sealing them, which is usually just a stop-gap measure. Flashing usually lasts for only 15 to 20 years, so a slate roof will require a roofer to replace its flashings several times over its lifetime.

Fastenings

Fastenings attach slate tiles to the roof. They’re typically nails, but they can also be hooks. Some types of fastenings also require wire in addition to the primary fastener. 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.

Restoration

Maintenance and repair is usually sufficient for most slate roofs. One exception is when it has been neglected for a long period, which often occurs with historical buildings. In these cases, a restoration may be a better choice than individual repairs. Restoration is a comprehensive form of repair that involves the entire roof, rather than specific area 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. However, 70 to 80 percent of the roof must still be viable to consider a restoration over a complete replacement. Restoration also requires the distribution of damage to be fairly even, instead of concentrated in one area.

Replacement

A roof generally requires complete replacement once 20 to 30 percent of the slates have deteriorated beyond reasonable repair. A slate roofer in your area 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:

Slate Roof Maintenance

Regular maintenance is one of the most important tasks for homeowners with slate roofs. This process should include regular inspections and prompt repair of cracked and fallen tiles by the best slater in your area.

Cleaning

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.

Treatment

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 a professional roofer should repair slate tiles.

Hiring

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, 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.

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 a number of alternative materials to consider when a replacement is necessary. These materials can provide the look of slate, but are less expensive and fragile.

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, but the color is also a property to consider when selecting a slate roof. The specific composition of slate primarily depends on its origin, which include New York, Vermont, Virginia and Pennsylvania. 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 $2.30 to $6 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.

FAQs

What are the different types of slate roofs?

The types of slate roof include standard, patterned and random systems. A standard system is composed of slates with the same length, width and thickness such that alternating rows have vertical joints that align. A patterned system uses slates of different shapes or colors to create designs. Random slate systems use tiles with different widths in patterns that provide adequate joint offset without maintaining joint alignment.

Are there alternatives to slate roofs?

The alternatives to slate roofs include fiber cement, concrete and clay. Fiber cement tiles are much cheaper than slate, but they don’t last as long. Concrete tiles are also less expensive than slate tiles, but are at least twice as heavy. Clay tiles last longer than the other alternatives to slate, but are so heavy they may require structural reinforcement.

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 they can apply 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.