Slate Roofing: A Comprehensive Guide

comprehensive guide to slate roofing

Dating back to the early 17th century, slate roofing is one of the most beautiful and durable roofing materials around.

Learn more about this century-old roofing material with the help of our guide to commercial roofing. Below, we outline the most common types of slate roofing available today, the advantages and disadvantages to a slate roof, and the cost of installation and repair.

On this page, we discuss...

Slate Roofing Thickness & Weight

Genuine roofing slates are split by hand using a hammer and chisel, revealing a naturally uneven surface that varies slightly in thickness.

These thicknesses are grouped into different groups, which can vary in weight:

Common Slate Roofing Thicknesses & Average Weights
Slate Thickness Average Weight
3/16" - 1/4" 800 lbs per square
1/4" - 3/8" 1,000 lbs per square
3/8" - 1/2" 1,400 lbs per square
1/2" - 3/4" 2,500 lbs per square
3/4" to 1" 3,000 lbs per square

Slate roofing shingles

Expected Lifespan of Slate Roofs

If you’re looking for a long-lasting roofing material, slate should definitely be at the top of your list.

There are documented cases of slate roofs in Europe that have withstood the elements for more than two centuries. A good-quality natural slate roof can be expected to last 60 - 125 years if installed correctly.

Because slate is an all-natural material, its quality varies. The ASTM grades slate roofing material on a scale ranging from S1 to S3. S1-grade slate is the highest quality and most durable choice.

Average Slate Roofing Lifespans
Grade Expected Lifespan / Durability
S1 75 + years
S2 40 - 75 years
S3 20 - 40 years

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Slate Roofing Materials Comparison

Historically, slate roofs have always been extremely heavy and quite expensive, but that's no longer the case.

Slate is naturally heavy, but modern manufacturers are finding ways around all this unnecessary weight. For example, GAF's TruSlate is made of genuine slate; however, instead of overlapping slate-on-slate—as is traditionally done—they've used a high-tech waterproofing material to help lighten the load.

There are other slate roofing options available, too, so be sure to compare your options before committing.

Slate Roofing Materials Comparison
  Traditional Slate GAF Truslate Synthetic Slate Slate-look Asphalt
Easy to install No Yes Yes Yes
Easy to repair/replace No Yes No No
Made from real slate Yes Yes No No
Affordably priced No Yes Yes Yes
Does not warp or curl Yes Yes No No
Individual slates can be adjusted after installation No Yes No No
Realistic slate appearance Yes Yes No Some
Lifetime limited warranty available on roofing system No Yes No Yes

Slate Roofing Pros & Cons

Slate Roofing Pros and Cons

Advantages of a Slate Roof

  • Highly-desirable appearance
  • Available as a natural slate or composite slate
  • Produces a one-of-a-kind roof
  • Fire resistant
  • Eco-friendly roofing choice
  • Very low maintenance
  • Weather resistant
  • Can last 75+ years

Disadvantages of a Slate Roof

  • Heavy
  • One of the most expensive roofing choices
  • Finding an experienced slate roofing contractor can be challenging in some cases
  • Natural material can shatter from strong impacts
  • Not suitable for commercial or low-slope roofing applications

Slate Roofing Cost

Natural slate roofing typically costs between $7 and $13 per square foot, but can reach as high as $25 per square foot installed.

The cost of installing a new, natural slate roof can vary significantly, and it depends on a number of factors, like the size and complexity of your roof, your geographic location, the slate material you're using, and more.

The prices below depict the average price for tearing off a single layer of roofing material and installing new slate tiles in various locations across the United States.

Average Cost for Natural Slate Roofing Installation
Location Roof Size Cost
Chicago, IL 2,000 sq. ft. $17,000 - $26,500
Atlanta, GA 2,000 sq. ft. $16,500 - $25,000
New York City, NY 2,000 sq. ft. $17,500 - $28,000
Los Angeles, CA 2,000 sq. ft. $17,000 - $26,000

(This pricing does not include costs associated with installing added ventilation or gutters. Contact your local slate roofing contractor for a customized quote.)

Synthetic slate roofing tiles may cost less, but they vary in quality and durability. The best quality synthetic slate roofing products have a thickness of ½-inch or more, carry a 50+ year warranty, are UL rated for impact resistance, are resistant to wind (110 mph+), and are Class A fire-rated.

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Slate roof repair

Slate Roof Maintenance and Repairs

Natural slate roofing requires basic periodic inspections and minimal maintenance.

Due to the longevity of slate roofing, it’s almost inevitable that repairs will be necessary at some point. However, slate roofs are almost always repairable.

It’s important to have cracked or missing slate tiles repaired as soon as possible. This helps limit water damage and potential damage to the surrounding roof. Luckily, an experienced slate roofer can replace individual slate tiles without having to remove a large section of the roof.

Sometimes slate roofing repairs aren’t the best option, particularly when a large portion of the roof is damaged. If 20% or more of the roof is damaged, it’s often more cost-effective to replace the entire slate roof rather than repairing the damaged areas.

Slate roofing

Warranties on Slate Roofing

There are two warranties to consider when working with slate roofing: manufacturer’s warranty and workmanship warranty.

Manufacturers' warranties protect against factory defects and are typically long-term, ranging from 50 years to a lifetime for natural slate products and 20 - 50 years for synthetic slate products.

It’s important to never purchase roofing based exclusively on the length of its manufacturer’s warranty. If you go with an S1 graded slate, it’s unlikely you’ll ever end up exercising the manufacturer’s warranty since you can expect to get 75+ years of usable service life.

In addition to a manufacturer’s warranty, most roofing companies offer workmanship warranties designed to protect your roof against damage directly related to the installation. Some workmanship warranties may also contain “leak-free guarantees” or similar language. Always read the fine print to make sure you understand what’s covered under your warranty and what isn’t.

Find the right roofing contractor for the job.

The roofer’s expertise and knowledge of slate roofing is far and away the most important factor to consider.

An experienced slate roofing contractor can recommend the optimal roofing material for your installation based on the local weather patterns and their experience installing and repairing a particular slate product.

It's challenging to find an experienced slate roofing contractor due to the fact it’s such a specialized type of roofing product and a high level of skill is required to get the job done right.

Hometown Roofing Contractors aims to simplify the process of finding the right roofing contractor for the job. We list the roofers' specialties and verified credentials, so you can find a qualified slate roofer quickly and efficiently.

We also publish roofing contractor reviews, ratings, and project costs. Hometown verifies every review to ensure that it comes from an actual customer, or we don't publish it.