Slate Roof: Buyer's Guide to Choosing the Right Type

Chris Gennone
Jan 6, 2021
5 min read

Natural slate roof

Image source: Matthews Roofing

With their old-fashioned Gothic appearance, slate roofs are one of the most eye-catching, durable, and longest-lasting roof types. Natural slate roof tiles are made up of hard metamorphic rock, which derives from sedimentary rock, usually made from clay or volcanic ash. So naturally, slate roofs are incredibly environmentally and eco-friendly. If you're considering installing a slate roof, let's explore what you should know before hiring professional installers.

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What You Should Look for Before Installation

Slate roof with a dormer window and a chimney

Image source: ASCH Roofing

Installing a natural stone slate roof is an investment. Finding the right contractor who is experienced with installing slate roofs is highly important, or you may find yourself paying for repairs more often than you should. But before installation, there are also several other points to consider to ensure your slate roof lasts as long as possible.

Structural integrity - Before hiring a professional roofer, we recommend you check with a structural engineer regarding the structural integrity of your home. Slate roofs are extremely heavy and can weigh four times more than an asphalt roof. Some homes may even require extra reinforcement before installation.

Where the rocks are from - It's important also to know where the slates come from. In addition to knowing the manufacturer, it makes a difference knowing where exactly the rock comes from as well. Some companies will even try to pass off fake synthetic slate shingles as real slate. Knowing where exactly the rock comes from can determine the lifespan of the shingles and the length of warranties.

Hard slate and soft slate - Another key point to remember is that there are two different types of slate available. Hard slate is incredibly durable and resistant to fire and moisture and can last up to 200 years. Soft slate is still very durable but has a shorter lifespan, lasting up to 125 years. Typically, most colored slates are hard slates while black slates are usually soft slates. While soft slate may not last as long, it is significantly cheaper, almost half the price of hard slate.

Selecting the right materials - Choosing the right materials is extremely important or your roof might need some unnecessary repairs. Make sure you try to avoid using any laminated woods or any kind of board that's glued together for your roof decking. Your roof decking should have the same lifespan as the slate. Instead, select solid wood boards as the sheathing. When selecting nails, remember that they should be twice as thick as the slates. We also recommend choosing between copper or stainless steel nails, which last longer than other metals that could rust over time.

Headlap - One of the biggest mistakes you or your contractor could make is not using enough headlap. Slate roofs with little to no headlap can result in large gaps, and the entire roof will have to be replaced. Depending on the slope of your roof, lower slopes should have a four-inch headlap and a three-inch headlap for steep-sloped roofs. Anything less than three inches though could be disastrous.

Hiring the right contractor - Another big mistake you could make is hiring the wrong contractor. If you’re investing this much money in a roof replacement, the last thing you want to do is have someone install slate poorly. Make sure you find a professional who specializes in installing a slate roofing system.

Cost of a Slate Roof

Slate roof with a dormer window

Image source: Top That Roofing

There’s no way around it, the cost of slate is high. While asphalt shingles can cost nearly $100 - $400 a square installed, slate shingles can cost between $150 and $3,000 per square installed. For an average-sized roof of 1,700 square feet or 17 squares, it would cost between $2,550-$51,000 to install a slate roof.

A synthetic slate tile roof can be a more cost-effective option but these tiles or shingles are typically made of rubber, which is not environmentally friendly, unlike natural stone.

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Types of Slate Roofs

Natural slate roof with a stone chimney

Image source: Slate Association

Before you install a slate roof, it’s important to determine which style suits your needs. While most of these styles offer the same benefits like durability and a long lifespan, they differ in thickness, color, texture, and pattern. Let’s discuss the options.

Standard Uniform Slate Roof

Close-up of an standard uniform slate roof

Image source: RestoreMasters

The name says it all. The standard uniform slate roof is the most common style found in the U.S., featuring slate shingles all cut into one uniform length and width. These slates are usually ¼”-?” of one standard length and width and assembled in a traditional horizontal shingle pattern.

Patterned Slate Roof

Close-up of a patterned slate roof

Image source: Black Diamond Slate

A patterned slate roof features different colored slates in different shapes laid out in a specific pattern. If you’re interested in a pattern slate roof, it is best to incorporate the pattern among standard-style slates. This arrangement will allow the pattern to pop.

Hang-Down Staggered Slate Roof

Natural slate roof

Hang-down or “staggered butt” slate roofs use slates that are of different lengths and widths, colors, and textures. With all different sizes and rough bottoms, the slates protrude over each other, creating a hang-down appearance.

Textural Slate Roof

Textural slate roof

Similar to the hang-down staggered slates, a textural slate roof has a more rustic-like appearance. These slate tiles have uneven butts, different sizes and thicknesses, missing slate corners, and tend to overlap each other. This creates a unique, textured look for your roof.

Graduated Length Slate Roof

Slate roof with dormer windows

Graduated length slate roofs emphasize the skill and craftsmanship of roofing. These slates are made with different lengths, widths, and thicknesses. The larger, thicker slates are typically placed at the eaves and the thinner slates are placed on top.

Why You Should Install a Slate Roof

Natura slate roof

Image source: Blue Nail Roofing

In addition to having a striking natural appearance, slate roofs are incredibly durable and long-lasting. While traditional asphalt shingle roofs and wood shake may be a more cost-effective roofing option, slate can last up to 150 years or more, requiring little maintenance. Slate is also fire and water-resistant, and can also help insulate your home in the winter, lowering energy costs. Slate roofing tiles are fireproof and resistant to moisture, making them better for homeowners living in colder, wetter climates. And if you do intend to sell, a slate roof could also increase the resale value of your home.

While a slate roof installation may be incredibly expensive, it’s an investment. Invest in the real thing. If you’ve found your forever home or plan on sticking around for a while, a slate roof is an excellent option.

Talk to local pros to get quotes on your slate roof installation project