When replacing an old roof or installing a new one, which roofing material you install is arguably the most crucial decision you’ll make. For best results, select a durable, weather-resistant material that will protect your home from the elements for a long time while adding curb appeal. Slate roofing outclasses most other roofing materials on all these counts.
Slate’s stony appearance gives it a classic allure that homeowners love, and it’s so durable that its lifespan can extend over a century. In that time, the slate will give your home’s interior unbeatable protection, and its superior insulation will also lower your utility bills.
The high upfront cost of slate is one of its few downsides. Slate is one of the most expensive types of roofing materials. You really get what you pay for with slate, though; its durability and long lifespan mean you probably won’t ever have to replace it again. Keep reading to learn more about the costs and benefits of slate roofs.
What is a slate tile roof?
A slate roof is a high-end roofing system made with slate tiles instead of alternatives like asphalt shingles, cedar shakes, clay tiles, or metal sheets. Slate is a hard, natural stone quarried from the earth, so it’s exceptionally durable and waterproof. When properly installed with weatherized fasteners and underlayment, a roof made with slate tiles is virtually weatherproof, fireproof, insect-proof, and impervious to many types of damage.
Slate roofs can last up to 200 years. While you have to do some routine roofing maintenance to ensure your slate lasts long, keeping up with the upkeep means you’ll probably never have to totally replace your slate roof.
If you’re considering replacing an existing roof with a slate roof, be aware that your current roofing structure may not be equipped to support slate tiles, so the swap may not be as easy as you expect. Slate roofs are very heavy—heavier than asphalt, concrete, and metal roofs—so you may need to reinforce your roof’s frame with support beams or replace your decking before getting slate tiles. Otherwise, your roof could buckle under its own weight.
This is part of why hiring a professional roofer is essential for this job. Without an expert to inspect your roof, there’s no way to know if your current roof’s structure is up to snuff. Of course, reinforcing your roof will add extra charges to this project’s already high costs, but it’s the only way to do the job right.
How much does a slate roof cost?
Slate is one of the most expensive materials used for roofing, and it costs anywhere between $11 and $20 per square foot to install a slate roof. If your roof measures 1,500 square feet, this project will cost you somewhere between $16,201 and $29,477. Your exact costs will depend on factors like the type of slate and the roof style you have.
These prices don’t include the costs to replace or reinforce your roof’s decking or frame, which can cost up to $10,000. If you simply need to replace a few weakened joists or add a few panels of stronger decking, the project probably won’t cost this much.
Unfortunately, you won’t know exactly how expensive your slate roof installation will be until you get a written estimate from a professional roofer. You should be prepared to spend around $40,000, though.
Different types of slate roofs
Slate roofing comes in a few different types, and not all slate roofs are equally durable. Firstly, there are three varieties of slate roofing materials.
Hard slate tiles
As the name suggests, hard slate is the strongest type of slate, so it has the longest life expectancy. Hard slate roofs can last up to 200 years. Most slate tiles that come in colors like red, green, gray, and purple are made from hard slate. On average, hard slate tiles cost between $15 and $30 to install per square foot.
Soft slate tiles
Soft slate isn’t quite as strong as hard slate, but it’s still highly water- and fire-resistant. It will weather and erode faster than hard slate, though, so soft slate roofs generally last no longer than 125 years. On the plus side, soft slate can be a little more cost-effective than hard slate as it only costs $10 to $15 per square foot to install. Usually, only black tiles are made from soft slate.
Synthetic slate tiles
Synthetic slate isn’t even really slate at all. Instead, it’s made from rubber that’s been molded to take on the appearance and texture of real slate. And while some synthetic slate tiles still provide Class A fire ratings and exceptional weather resistance, they fall short of natural slate in a few regards.
Firstly, they aren’t as environmentally friendly. Real slate is an all-natural material, so it’s less ecologically harmful to produce than synthetic alternatives. Additionally, real slate is biodegradable, whereas synthetic slate is made from materials that don’t biodegrade for a long time. Despite this, synthetic slate lags behind natural slate in terms of lifespan because it weathers (which is different from biodegrading) quicker. Most synthetic slate tiles only last 100 years.
So, why do some people opt for synthetic slate at all? First, it offers a nice mid-range between hard and soft slate price-wise. On average, synthetic slate tiles only cost around $7 to $12 per square foot. Also, synthetic slate is much lighter than the real McCoy, allowing you to get the classic slate appearance without installing support beams for your roof.
Different slate installation styles
In addition to the different types of slate—or imitation slate—used for roofing, there are also various installation styles. Before you install your slate roof, it’s essential to determine which style suits your taste. 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
A uniform slate roof with tiles arranged in neat lines looks similar to an asphalt shingle roof. Image source: RestoreMasters
The name says it all. The standard uniform slate roof features slate shingles all cut into one uniform length and width and arranged in straight lines. The lines are offset horizontally from each other to provide visual variety and prevent water from seeping through cracks between the tiles.
Patterned slate roof
The tiles in a patterned slate roof are cut from different slate colors and arranged to create attractive designs. Image source: Black Diamond Slate
A patterned slate roof features differently colored tiles laid out in a specific pattern. If you’re interested in a patterned slate roof, it is best to incorporate the pattern between lines of standard-style tiles to make the pattern really pop.
Hang-down staggered slate roof
The tiles in a staggered slate roof are less uniform than in other styles, giving these types of roofs a more rugged, cottage-style look. Image source: Northface Construction LLC
Hang-down or “staggered butt” slate roofs use slate tiles of different lengths and widths, colors, or textures. With all different sizes and rough bottoms, the slates protrude over each other, creating a hang-down appearance that can make a roof look more homespun and quaint.
Textural slate roof
Like the staggered roof style, a textural slate roof incorporates tiles of various sizes and textures for visual variety. Image source: RestoreMasters
Similar to the hang-down staggered slates, a textural slate roof has a more rustic appearance. These slate tiles have uneven butts, different sizes and thicknesses, missing corners, and tend to overlap each other. This creates a unique, textured look for your roof.
Graduated length/thickness slate roof
Graduated length slate roofs emphasize the skill and craftsmanship of roofing. The tiles on these roofs are made with different lengths, widths, and thicknesses. The larger, thicker slates are typically placed at the eaves and the thinner slates are placed at the top of the roof’s slope. This design creates an optical illusion that makes the roof appear much larger and grandiose.
What are the benefits of a slate roof?
There are many reasons to install slate roofs, chief among them being the longevity and durability of slate. Alternatives like asphalt shingles may be far cheaper than slate tiles, but they simply don’t last as long, so they have to be replaced more often. Since slate is fireproof, doesn’t absorb moisture, doesn’t rust, and isn’t edible to insects, it provides a sense of security that few other roofing materials can.
Additionally, slate can bring down your monthly energy bills. Slate is a fantastic insulator that counters thermal transfer, so it can prevent heat and coolness from escaping your home through your roof. This makes homes with slate roofs much more energy efficient than homes without them.
Finally, slate adds a romantic charm to a home, increasing its curb appeal. This beauty paired with slate’s durability can increase your home’s resale value. However, roofing replacements almost never raise your home’s value enough to recoup all the money the project cost, so resale value shouldn’t be the only reason you opt for slate.
What are the biggest problems with slate roofs?
Slate's only real drawbacks are its high price and its weight. Slate both costs and weighs several times as much as other roofing materials. And while the benefits of a slate roof are considerable, the strain on your budget and the potential need for extra structural support might make it an unrealistic option for your home.
How to maintain your slate roof
Slate’s durability makes it a very low-maintenance roofing material that doesn’t require much upkeep. That said, there are a few things you should do to ensure your slate lasts as long as it can. Here are a few quick tips for maintaining your slate roof.
Inspect the roof every year
Once the winter snow fully melts away each spring, you should hire a roofer to come out and inspect your slate tiles and flashings. Slate doesn’t absorb water, but it can erode over the years like any stone, and especially heavy hail can chip and crack slate. This makes it essential to check for worn patches and holes in your roof’s armor at least once every year. Otherwise, you won’t know about any damage until it becomes a leak which can be much harder and more expensive to fix.
Make necessary repairs quickly
If your annual inspection turns up any damage, take it seriously and don’t wait. Get the damage fixed as soon as possible. Small cracks in the slate could mean more extensive water and ice damage down the road, and missing tiles leave sections of your roof completely vulnerable to the elements. Better to nip these problems in the bud than to wait.
Clean your gutters
Keeping your gutters clean and functional is an important part of any roof’s maintenance, and slate roofs are no exception. Clogged gutters can lead to pools of water on your roof. The pooled water can then seep between your tiles and damage your roof’s structural decking, joists, and beams. Every season, use a ladder to reach your gutters and ensure they’re clear of leaves, sticks, animal nests, and other debris. Alternatively, you can hire a pro to come clean your gutters for you.
Slate roofing: the 411
Slate is one of the hardiest and most attractive roofing materials, so it’s no wonder that slate’s popularity is rising. Just be aware that the cost and weight of slate are serious hurdles to account for if you’re considering slate roofing for your home. But if money is no concern and you don’t mind reinforcing your roof’s structure pre-installation, you can’t go wrong with a slate roof.
Joe is a home improvement expert and content specialist for Fixr.com. He’s been writing home services content for over eight years, leveraging his research and composition skills to produce consumer-minded articles that demystify everything from moving to remodeling. His work has been sourced by various news sources and business journals, including Nasdaq.com and USA Today. When he isn’t writing about home improvement or climate issues, Joe can be found in bookstores and record shops.