Natural Slate vs Synthetic Slate

The topic of this post addresses the appropriation of the term slate. Appropriation is the action of taking something for one’s own use, typically without the owner’s permission. The manufacturers of synthetic slate have been misusing the word slate as their product is a rubberized polymer. The issue with this is that the uninformed homeowner can easily be mislead by incorrect terminology.

Definition of Slate

The Slate Roofing Contractor’s Association recently came up with a definition of slate and it is as follows:

“Slate is a naturally occurring, fine‐grained, metamorphic rock able to be split into tough, thin sheets for roofing, flooring, cladding, and other structural purposes.”

This is important because it describes what slate is not. Slate is not a synthetic, man made material out of rubber and plastic. 

The Issue

The natural slate industry is at a disadvantage for the following reasons:

  • Tipping Point of Slate – Slates installed in the early 20th century need to be repaired / replaced and the homeowners must decide their roofing material
  • Less Marketing Budget – The current slate industry is up against marketing budgets that have 5 figure booths at trade shows and promotional tools that fuel their agenda
  • Unclear Information – How can a homeowner make a decision when there are 2 products, both called slate, yet completely different?
  • Lack of Skilled Installers – Unskilled workers can do a poor job and give natural slate a bad reputation

Slate currently occupies a 1% market share of the roofing industry. The goal isn’t to grow to 10%, it’s to move the needle to 2%. There are various ways to attack this and it involves training contractors, keeping architects educated, making certain material distributors know slate is available, and informing the home owner of the decision they are making. Within a small industry, we need help to accomplish each individual piece.

Testing Fake Slate

This is a PDF from 2008 about tests being done on synthetic products.  A few highlights:

  • Virtually every product introduced during the 1980s and 1990s has been pulled from the market and is, fortunately, no longer available.
  • Current plastic and rubber slate and shakes do not have track records to match their warranties.
  • When the short-term test programs demonstrated the “new and improved” products could provide characteristics similar to the products they were replacing, the materials were introduced to the market. Most products were marketed with long-term warranties.
  • Offering new and untried products with 30- to 50-year warranties left users with an essentially untested product that ultimately failed within the first few years of installation by disintegrating on roofs when exposed to normal weather conditions. When such failures occurred, the industry was unwilling or unable to make good on its obligations because of the large financial burden of virtually a total failure of all products delivered and installed.

It should be noted that these are tests from 2008 and it’s not fair to equate this to material being released in 2019. However, that’s the point. Products in the field need to be tested in actual conditions provided by nature and not with short term results. Products can’t be warrantied for 50 years when they have only been created 5 years ago. Simple math. This is why the actual slate industry gets so steamed. Natural slate is time tested by nature. 


One of the hardest parts of being in the natural slate business is the information that is being produced by the pro-synthetic community. Here is a compilation of incorrect statements I came across through some research that I can cite if you email me, but my goal is not to attack anyone directly.

  • Natural slate roofs are actually highly durable, they look great, and they last a very long time. However, they’re among the most egregiously expensive roof types.

Expensive upfront costs should not be called “egregious”. Slate roofs provide high value over the lifetime of the roof. A slate roof signifies longevity in a structure that can last a century. Average slate lasts 100 years, good slate lasts 150, and great slate can last 200 and counting.

  • Synthetic slate is a great roofing alternative because it’s one of the safest and most durable roofing choices you can make.

Anyone can write this, but my guess is the facts won’t back this up.

  • Synthetic slate, by extension, is gaining in popularity as a less-expensive, more efficient alternative.

The only extension is that both materials are rectangular.

  • Synthetic slate is much more durable than true slate. 

More durable in what sense?

  • Synthetic slate shingles are a modern improvement on a construction classic. Made from combinations of plastic and rubber, synthetic slate is designed to mirror the beauty and uniqueness of authentic slate without the expense or installation headaches. 

This is a marketing statement. No one who knows slate would agree that synthetic mirrors the beauty of slate.

  • Synthetic slate shingles are more durable than authentic slate, as they contain advanced ultraviolet inhibitors to reduce wear from the sun.

As written many times, synthetic has no track record to say that they last longer than natural slate.



  • Installing a roof system that has less of a track record than its expected life is an experiment; this is acceptable as long as its owner is a willing participant.
  • Only a roof system’s historical durability in a similar environment is an appropriate performance indicator.
  • Warranties are legal documents used as sales tools and provide more protection for roofing manufacturers than they provide purchasers.
  • Natural slate is a green material that comes from the Earth. Synthetic is marketed as green, but that’s only if you separate the nails, underlayment, and “goo” that is attached to them after installation, which roofing contractors won’t do.
  • As an uninformed consumer to “slate”, you can see why posts like these need to be written.
  • Support the hardworking people in the quarries.