How much does it cost to repair a slate roof?

Reviewed by Adam Graham remodeling expert. Written by Fixr.com.

Slate is one of the toughest and most beautiful materials for a roof, and many homeowners enjoy the unique look. However, slate roofs can suffer from a range of problems, including broken tiles, damaged flashing, underlayment issues, and leaks. When these issues occur, you need to contact professionals to repair your slate roof.

The national average cost for slate roof repair is $300 and $1,500, with most homeowners spending around $900 to replace a couple of damaged squares of underlayment and some slipped tiles after a storm. This project’s low cost is $50 to replace a single synthetic slate tile. The high cost is $4,000 for extensive repairs after a severe hail storm.

Slate Roof Repair Cost

Slate Roof Repair Cost by Type

One of the factors influencing the cost of your repairs is the type of slate roof. Some slate roofs are made with synthetic materials, while others are crafted from natural slate, and others are made with a hybrid material. Depending on the material, certain repairs cost more or less, such as shingle replacement.

Synthetic Slate Repair

The average cost of synthetic slate roof repairs is between $5 and $13 per sq.ft. Synthetic slate roofs are usually the cheapest to repair because the material costs of replacing synthetic slate sections are inexpensive. On the downside, synthetic slate tiles are more likely to crack and break than natural or hybrid slate, so you may have to deal with more frequent problems and repairs.

Repair Hybrid Slate

Homeowners usually spend between $6 and $14 per sq.ft. on hybrid slate roof repairs. A hybrid slate roof features a mixture of real slate tiles set on synthetic waterproofing materials. They are the ideal compromise between natural slate and synthetic slate, aiming to offer the best of both worlds. Still, hybrid slate roofs can suffer from various problems like broken tiles, leaks, and underlayment damages.

Natural Slate Repair

To repair a natural slate roof, expect to pay $7 to $15 per sq.ft. Natural slate roofs are the most expensive to install, maintain, and repair, due to the high costs of slate. Slate is a strong material and can withstand a lot of damages, but tiles may crack or fall, and you may need to pay for other repairs like fixing leaks, chips, and water damage.

Slate Roof Repair Cost by Type of Repair

The cost of your slate roof repair may also depend on what damage has been done and how much work is needed to fix it. Various sections of the roof can get damaged from storms, weathering, or general wear. Certain parts are easier and cheaper to fix than others. The table below shows common slate roof repairs and their average costs.

Slate Roof Underlayment Repair

The average cost to repair slate roof underlayment is between $150 and $350 per square. A square is equivalent to 100 square feet, and it is common for roof repair specialists to charge by the square when quoting prices for underlayment repairs. Underlayment is placed underneath the slate roof tiles to provide an extra layer of water protection for the roof. It can get damaged and develop holes, but a repair worker can patch the holes to fix the underlayment.

Repair Slate Roof Flashing

Homeowners spend between $200 and $300 on slate roof flashing repairs. Flashing is a metallic material usually found around the outside of the chimney. It is designed to provide a waterproof seal for areas prone to damages and leaks. Flashing can get worn with chips and cracks. It may be possible for a repair specialist to patch these damages without replacing the flashing entirely.

Cost to Fix a Slate Roof by Type of Replacement

In many cases, damaged parts of your slate roof must be replaced. The cost of slate roof replacements varies depending on which part needs replacing. Some elements are much cheaper and easier to replace, and the table below shows common slate roof replacements and average costs for each.

Replacing Slate Roof Tiles

The average cost of replacing slate roof tiles is between $50 and $200 per tile. The price depends on several factors, such as the tile type and size. Naturally, small synthetic tiles are much cheaper than larger tiles made from natural slate. Tiles must be replaced if they have broken, cracked, or been seriously damaged.

Replace Slate Roof Fastenings

Expect to pay $150 to $650 to replace slate roof fastenings. The price depends on the fastening type and how many are needed. Typically, copper, stainless steel, and galvanized steel nails are used as fasteners for slate roofs. These fastenings can become loose, rusty, or brittle and need to be replaced to maintain the roof’s solidity and structure.

Replace Slate Roof Flashing

The cost of replacing flashing on a slate roof varies from $200 to $1,000. The price mostly depends on how much flashing needs to be replaced and how accessible the affected area is. Flashing can last for many years and is made to be resistant but it naturally wears, and severely damaged flashing must be replaced to prevent leaks and water damage.

Slate Roof Underlayment Replacement

The average cost to replace underlayment in slate roofs is between $350 and $550 per square, with one square being equivalent to 100 square feet. Depending on your roof size and damage, you may need to replace multiple squares of underlayment, leading to high costs. Underlayment may need to be replaced if it has holes or tears and is causing leaks.

Slate Roof Repair Cost by Problem

Many issues can occur with slate roofs, from relatively minor issues like slipped tiles that need replacing to more serious and widespread problems like leaks, hail damage, and asbestos problems. Depending on what issue you are dealing with, repair costs can vary widely. The table below shows common problems and average repair costs on a typical slate roof of 1,500 square feet.

Repair Slipped Roof Slate

Homeowners pay between $50 and $200 to deal with slipped tiles from a slate roof. Individual slate tiles can slip from the roof and fall due to storms, wear, and fastening problems. You usually must replace the slipped tiles and fit some new fasteners. It may be possible to put the slipped tile back in position to save money if the tile is intact.

Chipped Slate Tiles

For chipped slate tiles, homeowners spend between $75 and $200 for repairs. In some cases, chipped tiles can be left in place and may need minor patching or new fasteners if the damage is only minor. In other cases, the damaged tiles must be replaced.

Cracked Slate Roof

Repairs for cracked slate roofs average $75 to $250. Usually, if a tile is cracked, the best thing is to replace it with a new one. It may be possible to patch minor cracks, but larger cracks get larger over time and could eventually lead to leaks. You pay more to repair cracks in real slate tiles than in synthetic or hybrid ones. You may also need to pay extra if the underlayment is damaged.

Hole in a Slate Roof

To repair a hole in your slate roof, expect to spend between $100 and $500. The cost mainly depends on the hole size and scale. A small hole in a single tile can be patched cheaply and simply, but larger holes going through the tiles and into the underlayment can be more costly.

Slate Roof Leaking

Repairing a leaking slate roof averages $250 to $1,000. The total price depends on the extent of the damage. Some leaks are relatively minor and can be fixed by replacing cracked or damaged tiles, while others require more extensive underlayment replacements or flashing repairs.

Asbestos Slate Roof Repair

The average cost of dealing with asbestos in a slate roof ranges from $500 to $2,500. The price depends on the extent of the asbestos problem. Asbestos may be present in slate roof tiles, soffits, and other sections of the roof structure. You may have a higher cost if the problem is more widespread.

Water-Damaged Slate Tiles

Homeowners pay $500 to $3,000 to fix a water-damaged slate roof. Slate is designed to be water resistant, but water can penetrate beneath the tiles, pass through gaps and weaknesses, and damage the roof’s structure. You may even have to deal with issues like rot, mold, and algae in slate roofs if water problems are not fixed, so the roof may need restoration, cleaning, and sealing.

Hail Damage to a Slate Roof

Homeowners pay between $700 and $4,000 to repair hail damages to a slate roof. The price mostly depends on how much damage has occurred. After a hail storm, you may find a range of issues on your roof, such as damaged fasteners, slipped tiles, cracks, holes, and other damages. So, the roof may need to be patched and restored, and certain elements may need to be replaced.

Slate Roof Repair Prices by Solution

Repair workers may use various repair methods on your slate roof, depending on the damages and problems. For example, a slate roof suffering from water damage may need to be sealed, or one that has become covered in dirt and algae needs to be cleaned. The table below shows common repair methods and solutions for slate roofs, with average costs for each.

​​Clean a Slate Roof

The cost to have a slate roof professionally cleaned is between $0.30 and $0.70 per sq.ft. To clean a full-sized 1,500 sq.ft. roof, expect to pay between $450 and $1,050. Slate roofs may need to be cleaned if debris, dirt, and algae have built up around the tiles. Usually, low-pressure washes are used because high-pressure blasts can dislodge and damage the tiles.

Reinforce a Slate Roof

The average cost to reinforce a slate roof varies from $150 to $1,000. Various methods may be used to reinforce the roof. One common method is to replace the fastenings, using strong, galvanized steel nails to provide maximum strength and stability. New battens may also be required to reinforce an old and damaged slate roof.

Seal Leaking Slate Roof

Homeowners spend between $500 and $2,000 to seal a leaky slate roof. Be careful when sealing slate roofs because some sealants may cause the slate to age faster and do more harm than good. Slate roof specialists must be contacted to use the correct products and techniques to waterproof the roof, such as cement mixtures and butyl tape.

Labor Cost to Repair a Slate Roof

The average labor cost to repair a slate roof is between $50 and $100 per hour. You may find some roofers who charge per hour, while others give you repair quotes based on the job size and scale. Some repair companies have set fees for certain tasks like replacing a slipped tile. Prices vary by location, depending on the competition. You may have to pay extra if you live in a remote location because the workers must travel farther to get to your home.

Some repair workers also charge a call-out fee of $50 to $75, which may be waived if you hire them for the repairs. You also typically pay extra for emergency slate roof repairs, so consider this if you have an emergency situation like a sagging roof or bad leak.

Slate Roof Maintenance

One of the best ways to reduce the risk of slate roof problems and hefty repair bills is to keep your roof in good condition. Homeowners can take several steps to maintain their slate roofs, starting with regular visual inspections. Keep an eye on your roof for loose or falling tiles or other noticeable damages. It is especially important to look at the roof after bad storms or during the winter because this is when problems are most likely to occur.

You can also schedule professional inspections of your roof. For an average cost of around $200 to $500, a slate roof specialist visits your home, climbs onto the roof, and inspects it for damages. They provide you with a full report of their findings and suggest repairs or replacements that may be needed.

You should also try to keep your slate roof as clean as possible. It is best to leave cleaning to the professionals because you may damage your slate roof when trying to clean it using a standard pressure washer. Professionals clean a slate roof for a cost of around $0.30 to $0.70 per sq.ft., using gentle cleaning solutions and low-pressure washes.

Repair vs Replace Slate Roof

If your slate roof is badly damaged and needs repair, you may wonder if it is best to replace or repair the roof. You must consider several factors to make this decision, including cost and age.

Cost is a key factor to think about. The average cost to replace a standard-sized 2,000 sq.ft. slate roof is between $30,000 and $50,000. This is much more than any individual slate roof repair job. However, if your roof is repeatedly suffering from damages and has to be repaired regularly, you may find that you could save money by replacing it with a new one, which does not need to be repaired as often.

You also have to think about age. A synthetic slate roof can last for around 20 to 50 years, while natural slate roofs last from 50 to 200 years before needing to be replaced. So, if your slate roof is old, it may be nearing the end of its lifespan and will continue to cause problems and cost you money in repair bills until you replace it.

Enhancement and Improvement Costs

Gutter Replacement

Homeowners pay between $900 to $5,000 for gutter replacements on a slate roof. The reason for this wide price range is because there are many materials and styles you can use for gutters. Some are inexpensive and simple, while others are more decorative and expensive. Most people pay around $1,400 for 150 linear feet of seamless aluminum box gutters.

Additional Considerations and Costs

• Lifespan. Synthetic slate roofs can last for 20 to 50 years, while natural slate roofs may last up to 200 years. Roofs become more prone to damage and wear as they get older.
• Permit. Depending on building codes in your location and the extent of roof repairs you require, you may need a permit. Check with local authorities to be sure.
• Licensed professional. Slate roofs must be handled with care by true professionals, so ensure you work with licensed roofers who know what they are doing.
• Insurance. Your homeowners insurance may cover certain kinds of roof damages, such as damage caused by hail. Check the policy to see if you can make a claim.