What Are the Pros and Cons of Slate and Tile Commercial Roofs?

If your building has a slate or tile roof you can expect it to last up to 100 years or more — how’s that for longevity? The reason these roofs have been so popular for centuries (millennia, actually) is that they’re durable, beautiful, do a great job of protecting buildings, and, in the long run, provide excellent value even though they’re expensive to install. The materials are also sustainable, which is increasingly important in today’s market.

Slate and tile commercial roofs are often considered the best available. But they can also be a challenge to repair and replace. This post is part of our series on Pros and Cons of the most popular commercial roofing systems. Check out the other posts and learn about all the systems: TPO, EPDM, metal, asphalt, and vegetative.

You can also see our Guide To Commercial Roofing Systems: Pros and Cons that covers highlights of each system in a PDF you can view online or download.

Slate and tile roofs

Slate and tile are natural products. Slate shingles are quarried from mines and clay tiles are fired, as with earthenware. There are also plenty of synthetic options available now. During installation, the shingles are hung in rows using nails attached to a framework underneath, with the shingles overlapping each other so the nails are hidden and rainwater flows over the top of the shingles. This system has worked perfectly since about 2500 BC, or more than 4,500 years.

If a building has a slate or tile roof, it’s usually a critical part of a building’s design. The exact texture, length and other shingle qualities are often specified by architects. A sleek, modern slate roof, for example, will call for a different shingle length, color and thickness than a roof on a centuries-old country estate.

Synthetic materials

Synthetic (faux) slate shingles look like the real thing but are made from composite materials — plastic or rubber — so they don’t break as easily and cost about half as much as natural slate. They also last about half as long. Faux tiles and faux cedar shakes have the same properties and longevity as faux slate. Concrete tiles, which look like clay tiles, are another less-expensive option and also have a life expectancy of up to 50 years.

The Pros:

Traditional slate comes in many varieties of colors, thicknesses, and grains, and is considered to be the most sophisticated roofing option. It’s also the longest lasting roofing system — a high-quality, properly installed slate roof can last 150 years. The slate tiles themselves can last even longer (400+ years) so they can be used again and again. Weathering characteristics vary for natu

ral products. Slate shingles may be “unfading,” “semi-weathering” or “weathering.” Just as copper ages to a fine patina, slate can hold its basic color for years or mature into elegantly weathered hues depending on the type of slate.

Clay tile roofs are also extremely durable with life expectancies between 75 and 100 years. Colors vary from classic terracotta red and other reds to greens, grays and blues. Finishes vary, too. You can expect color fastness of premium tiles to last for as long as the tiles themselves.

Natural slate and tile roofs are:

• Durable — last for 50, 75 or 100 years and even up to 150 years
• Practically maintenance-free
• High-performing under the harshest conditions, including natural disasters
• Energy efficient, with insulation qualities that keep buildings cooler in summer and warmer in winter — some shingles are Energy Star rated and can earn LEED points
• Fire resistant
• Pest resistant
• Easily cleaned and reused
• Recyclable, and some clay tiles are made with recycled post-industrial materials
• Often a good investment, increasing architectural impact, curb appeal and overall property value

The Cons:

While exceptionally durable once installed, slate shingles are fragile during installation. Artistic skill is needed to coax out the color magic in the shingle pattern so it looks random and natural, not checkerboard. Installers must be able to drive nails down to 1/8 inch above the shingle but no further. Since shingles hang on the roof substrate like a picture hangs on a wall, enough nail length must remain for them not to slide off of the roof. Yet, if slate is hit with a hammer, the hairline crack that results will cause the shingle to fall apart within a few years. If a shingle in a visible area gets cracked, a skilled artisan will be able to replace it with one from a more hidden area of the roof and then integrate a new shingle into the more hidden area so differences in patina aren’t noticeable.

To be properly installed, tile roofs require countless decisions during planning and installation. Moisture penetration can be an issue so it’s critical that the underlayment, batten system and flashing are installed correctly — quality materials should be used throughout the project. Installing or repairing a slate or tile roof is not a job for inexperienced craftsmen.

Other cons for slate and tile roofs can include:

• Cost (initially)
• Experienced specialists to work on your roof, which can be tough to come by in many areas
• Specialists need to know the right fabrication techniques for your type of shingle for proper life expectancy
• Takes longer to repair and replace the roof — it’s an intricate process, especially if you need to remove the entire roof to replace the substrate and then clean each tile and put it back
• Designing the roof so technicians can access it for maintenance duties, such as servicing air conditioning units
• Risk of cracked shingles if crews don’t use “walk boards” or specialized rigging for difficult-to-reach places

Crews also need to know how to install Heritage copper guttering systems, a high-end 1/2 round gutter system that works in conjunction with slate and tile roofs and last just as long.

Warranties

Depending on the material and manufacturer, warranties for slate and tile roofs are usually 50, 75, or even 100 years. Sometimes a labor warranty of 20 years or lifetime is included as well. Most synthetic slate roofs and concrete tile roofs have 50-year warranties.

Sentry Roof is one of the few roofing companies in metro Atlanta that has the experience and skillsets to repair and replace slate and tile commercial roofs — our specialists are true craftsmen. We are proud to have worked on many of Atlanta’s historical slate or tile roofs, including Piedmont Driving Club, Agnes Scott College and Atlanta First United Methodist Church (renovation work currently in progress). We’ve also installed plenty of new slate and tile roof — some of them even have fun stories that go along with them. Our clients like that we’re well-versed in all slate and tile materials (including synthetics) and have relationships with distributors all over the world, from slate quarries in Vermont and Spain to hand-crafted tile manufacturers in Italy and Spain. Special orders and complex projects are welcomed.