Slate FAQs

Is slate readily available?

Yes, here in the United States, natural slate roofing and tiles are available from several different sources. Most of the US companies have one quarry or one color of slate and source out any other products that their customers might be seeking. There are only one or two companies here in the United States that truly offer a full range of domestic and imported Slates from around the world. The slate industry is leaning toward a global market. For example, 15 years ago in England their domestic slate, called Welsh slate, dominated over 98% of the British slate market. Today, it is less than 10% of the market due to the increase in imported products. The imports offer different qualities, varieties, more availability and different ranges of pricing. If global trends continue towards a “single world market”, then the likelihood of growth for the imported slates here in the United States is great and will continue to have a strong future.

In the United States, quarries are generally producing one or two truck loads a month, which equates to fifty to one hundred squares, with only a few quarries capable of producing more. In Europe, there are many “mom and pop” operations that produce over 180,000 to 200,000 squares a year or 3,600 squares per week. That would be approximately 72 full truck loads per week.

The demand for Natural Slate Roofing here in the United States can easily be supplied from producers around the world. As the production in the United States is limited, we as global consumers benefit greatly from slate produced worldwide.

How much does slate weigh?

Slate weighs between 800 to 1,000 pounds per square, or eight to ten pounds per square foot. The weight of each slate piece is directly related to the thickness of each piece of slate. The thinner the slate, the lighter it is. The thicker the slate, the heavier it is. Since all slate roofing material is still hand split today, the thickness for each slate varies according to the eye of the splitter.

    Most producers offer slate in several ranges of thickness:

  • 1/ 4” – 3/8” about 900 to 1,200 pounds per square
  • 3/8” – 1/2” 1,200 to 1,800 pounds per square
  • 1/2” – 3/4” 1,800 to 2,500 pounds per square
  • 3 /4” – 1” 2,500 to 3,300 pounds per square

The majority of slate sold today in the United States is 1 /4” – 3/8” thick.

How much does slate cost?

Natural slate today cost between on average $400.00 to $500.00 per square. Slate roofing in the United States today normally runs around $400.00 per square plus the cost of shipping. Some softer weathering or fading slate is less expensive because they are easier to mass produce. Harder unfading slates are more desirable and thus bring more of a premium because it is harder to mass produce. The size of the slate also affects the cost of the material as well as current stock levels. Thicker slate costs are normally higher because there is more material per piece, thicker material is harder to produce, there is more trim work usage and the cost of shipping is higher due to the additional weight of each piece of slate.

Slate jobs are priced out individually because of the variables of product color, size, thickness, quantity, current availability of that requested size, and shipping cost. There is no such thing as a normal cost. One can only give a ballpark figure until the project progresses to a point where more of the decisions are made regarding the different variables. Only then can a true cost be determined for the material. And as we all are aware, in our current time shipping cost are always subject to change.

Are there different sizes, thickness and colors?

Slate lengths are: 12”; 14”; 16”; 18”; 20”; 22”; and 24” and the widths are usually determined by the length of the slate. The width is never less than half of the length. In other words, a standard slate cannot be 18” long by 6” wide. The width would have to be minimally 9” which is half of the length.

Slate length, width and thickness vary. Since slate products are natural stone, the product can usually be cut to a customers requested size in length, width and thickness. Any deviation from standard production demands a premium price.

Unfading Slate is normally a harder stone that changes very little from it’s freshly quarried look. Whatever changes occur are uniform typically throughout a slate roof provided that the material comes from one quarry. Unfading Slate products are in higher demand over the “weathering” slate products and command about a $100 premium more than the
weathering slate.

There are also Fading Slate or “Semi” Weathering Slate, that change color once exposed to the weather. The reason for this change in the color is due to the high percentage of Iron (Rust) and Calcium, which causes the slate to lose its color pigment. These slate normally turn brown in color. These softer semi-weathering slates are often considerably less expensive and can cost in the lower $300.00 range.

What does standard or random mean?

Standard means all of the slates are the same size in both length and width. Random is where all of the lengths are the same size but the widths will vary. In this case all of the slate would have the same exposure, it is just the width of each slate piece that would be “random” or varying. In some cases, different patterns can also be achieved in the thickness of the slate and this is called graduated. This is where the thickness of the slate at the bottom is thicker and gradually the thickness decreases as it goes up the roof. This is more common in old European homes and newer affluent homes. This is the costliest application of all. The bottom line for the owner of the project is to determine what look they are going for at what price. But it can be easily said that all slate roofs are unique, beautiful, and last a lifetime.

How is slate installed? Are instructions available?

Slate is still installed the way it has been for hundreds of years. Most slate comes with two pre-punched holes, to enable the installer to nail it to the roof. Manuals with complete instructions on how to properly install a natural slate roof are available on our “Resources” (click here to visit.) page. Or call us at 804-745-4100. Our company will e-mail; fax, or mail our entire manual on how to install a Natural Slate Roof free of charge.

What is the benefit of slate? Why select slate?

Natural slate roofing is:

  • Leed certified Green
  • Recyclable
  • Extremely durable and has a long life expectancy
  • Environmentally friendly, a natural product from the earth
  • Requires minimum repairs, ease in care and maintenance.
  • High re-sale advantage/good salvage value
  • Excellent fire retardant
  • Insurance and loan advantages
  • The Natural beauty of the product
  • One of the few roofing products that have truly been tested by time

What is S-1? What is Miami-Dade County approved?

The American Society of Testing on material has established a standard specification for roofing slate, C-406, which tests the slate for three physical requirements that the slate must pass to be classified as S-1 Slate.

• C -120- Modulus of Rupture of Slate
• C- 121- Water absorption of Slate
• C – 217- Weather resistance of Slate

All of our slate at The Virginia Slate Company has been tested and retested over the years and qualifies as S-1 slate. In addition, all of our slate is Miami-Dade County approved. In order to have your product “Miami-Dade-County “ approved the product must pass many stringent tests including the wind up-lift test where the slate is tested on a roof and subject to 110 mph wind with gust up to 140 mph. This test is by far the most severe test for any roofing product to pass. If your product fails any one of the tests, the product can not be “Miami-Dade-County Approved”.

How is slate produced?

Slate is natural stone. Natural stone, like slate, is found in the earth in a few select places. The slate is drilled, blasted and/or sawed from the ground. The slate is removed in huge slabs that are extracted from the quarry to produce varying slate products. These large slabs are then sawed down to size and split into thick blocks. The blocks are then split by hand down to chips. These chips are then trimmed to a specific size and punched leaving a nice beveled edge around all four sides of each slate. The slate product is then crated in pallets and shipped to markets around the world.

How is slate sold?

Slate is sold both through distribution and direct to the contractor or owner of individual projects. It is my belief that most of the slate industry in the United States would rather sell through distribution, if given a choice. The slate industry has never supported distribution and distribution has never supported the slate industry. The domestic supply of slate has historically been low in supply, so there was not a need for distribution as much. Today, that has changed.

With the massive increase in supply that is now available from around the world here in the United States, I believe distribution is going to become more important to this industry.

    Advantages of Distribution :

  • There is a comfort level in dealing with one’s local supplier of roofing products
  • Logistic issues are handled easily by distribution
  • With distribution, no deposit or COD is required. Terms of 30-90 days are given depending on the relationship with the distributor
  • Distribution helps creates more awareness and knowledge of Slate to the average customer. Helps them understand that there is an abundant supply in the United States Market today

Natural Slate Vs. Fake Slate

The introduction of Fake or Synthetic Slate over the past few years in the United States, has both helped and hurt the Natural Slate industry. On one hand it has brought a renewed awareness to Natural Slate that over the years had been slipping from the general public. But on the other hand, in the effort to sell Synthetic Slate, this new industry has made several statements that are misleading. An of example of this would be the statement that the cost of Synthetic Slate is “for a fraction of the cost” of Natural Slate. What is not being conveyed to the roofing contractor or the owner(s) that the cost is a very large fraction. I have recently verified that the cost difference was minimal. The current price for the “Fake” slate is approximately $350.00 for the material plus the trim and accessory pieces plus the cost of shipping which reflects an estimated cost of $400.00 per square.

Natural Slate runs from about $350.00 to $500.00 per square delivered to the job site. The price of Natural Slate is normally determined by whether the slate chosen is an unfading or “weathering” slate, the size of the slate, current inventory of production levels of the particular size chosen, the quantity of slate requested and what the shipping requirements are. Currently the cost of real slate is clearly in the same range as the “cheaper” alternative and ultimately a much better choice. It is also in the interest of the Contractor and Owner to review the difference in the Warranty. The Natural Slate roof product warranty for an S-1 slate is for an excess 75 years compared to the warranty for “Fake” material which is often dubious at best. The negative issues that face the new “fake” slate material have been numerous. With the true difference in cost between Natural versus Fake Slate products installed between 10% to 20% more, is the small savings really worth the risk ?

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