Slate roofing was once the material of choice for high-value roofs. Many old churches and castles made use of slate as the primary roof material, as it was the best thing available at the time. Even today, slate remains the premier choice for those who want the best. Even with all the modern roofing materials out there, slate has retained its position near the head of the pack.
Slate roofs have some serious pros and some serious cons as well. When you get a roof of this sort, you need to be well-educated about these pros and cons so that you can be prepared for whatever may come.
Benefits Of A Slate Roof
Slate roofing has a unique arsenal of advantages that explain why such a “primitive” material is still in use today. These include beauty, longevity, insulation value, and safety.
Beauty
This is the primary reason that high-end homeowners are drawn to this material. The look of natural stone is something that cannot be fully duplicated by modern materials, and that’s why it has remained as a premium building material. In fact, you may have noticed that many commercial shingles try to mimic the look of natural stone. Sure, fake stone might look halfway decent, but there is no substitute for the real deal.
The color and texture of natural stone will add an element of beauty to your roof that cannot be obtained from any other roofing material. Also, you might be surprised at the number of colors in which slate can be found. While grey is by far the most common color, you can find slates that are green, black, red, or even purple. Apart from its natural colors, slate can also be dyed to produce nearly any color or color pattern that you want.
Longevity
Along with its beauty, longevity is the other big advantage of a slate roof. Because they are made of stone, a slate roofing tile will have already endured the weather for thousands (if not millions) of years. Have you ever noticed that the oldest monuments still standing are all made of stone? That’s not a coincidence.
When roofing companies install a roof of this type, they typically guarantee their work for a long time indeed. It probably helps that they don’t have to worry about manufacturer defects since this material is not manufactured. While many types of roofs will require maintenance and repair within a decade, a slate roof is expected to last anywhere from one hundred to one hundred and fifty years.
Slate can also do a much better job of handling adverse weather than most other materials. For an idea of how that works, check out this study. In this test, researchers measured the bending strength of slate under a variety of temperatures. They subjected the stone to a cycle of freezing and thawing, to see if the flexibility of the stone could be altered. They found that repeated freezing and thawing would indeed make the stone a little more flexible.
At the same time, the stones also developed micro-cracks that could eventually cause breakage, but bear in mind that they were changing the weathering conditions of these stones far more quickly than nature would ever do. Have you ever taken a hot glass out of the dishwasher, only to have it shatter when hit with cold water? That’s the effect that we are talking about here.
Insulation Value
As you may know, there are a lot of materials that can help to insulate your home from outside temperatures. We have seen old houses in which newspaper was stuffed into the walls as insulation, which gives you an idea of how many things can be used to provide extra insulation in a home.
However, not all of these insulation materials are equal in terms of their ability. As you might guess, newspaper insulation is not very high on the list but is certainly better than nothing. Slate, on the other hand, has great insulation properties. Because it is so dense and hard, it is nearly impossible for cold or hot air to get through your slate roof.
This will translate to a greater level of home comfort, and also a reduction in your electric bill. It’s hard to say how great that reduction will be, as the reduction will also depend on your actions. It won’t do as much good to install a slate roof if your home and habits are not energy efficient in the first place.
It should also be noted that stone walls or roofs will require some form of insulation underneath them in order to achieve optimal insulation. Although the dense structure of the stones makes it harder to penetrate, stones can still conduct and hold both heat and cold. Without an additional barrier underneath, stone roofs and walls will allow some hot and cold energy to pass through. However, when combined with an underlayment, they work extremely well.
Safety
For those who are paranoid about house fires (and you should be), slate is ideal roofing material. Natural stone is one of the few materials out there that simply does not burn. With enough heat, slate can crack, but that requires extreme heat that will only be present if your house is already engulfed in flames.
Slate is also completely nonconductive, meaning that electricity cannot travel through this material at all. Thus, any danger of electrical hazards is also reduced. All in all, slate has a safety factor that should make anyone stop for a second look.
Drawbacks Of A Slate Roof
In spite of all these great advantages, there are also reasons for the fact that slate roofing isn’t used all that much. These include cost, installation problems, weight, and impact resistance.
Installation Problems
As we mentioned earlier, slate roofs are not used all that much these days. As a result. there are fewer contractors and companies that know how to properly install this material. That can make it a little bit hard to find the right contractor. Even when you do find a good slate roof contractor, you will likely have to pay a lot more for such specialized services. Those who repair slate roofs don’t get as many opportunities to use those skills, so they have to charge more for each job.
Perhaps the worst thing about this factor is the fact that contractors are not always honest about their capabilities and experience. When you request a slate roof, they often won’t tell you if they have the experience to do the job correctly. Naturally, they don’t want to lose your business. As such, they will probably tell you that they can do the job even if their company has never done a single slate roof in the past.
When you are thinking about hiring a particular roofing contractor, ask for some references and ask to see some of their previous work. Make sure that the previous work includes at least two slate roofing jobs. We would suggest that you not ask them to include slate jobs in their portfolio, because a decent and experienced slate roofer should include that regardless. If you ask for a portfolio of their recent work and they hand you nothing but pictures of non-slate roofs, just walk away and find a more honest contractor.
Weight
Slate is not a good roofing material unless your home is strong and structurally sound. We say this because slate is probably the heaviest roofing material on the market. This extra weight is probably the main reason that it is less used today. In order to cope with the extra weight of a stone roof, a structure needs to be well-reinforced.
We all know that rocks are heavy, but how heavy are we talking here? Let’s see if we can find some exact numbers to settle the question. This handy material weight calculator should give us a decent estimate.
If we assume that each tile is a quarter-inch in thickness, six inches wide, and one foot long, we get a weight of 1.74 pounds per shingle. When you consider all the shingles that a roof requires, that comes out to a really large amount of weight. For comparison, let’s calculate the weight for a piece of oak that is exactly the same size. An oak shingle of this size would weigh about 0.5 pounds. In all, slate is nearly as heavy as granite or marble.
Impact Resistance
Slate does an amazingly good job of resisting the weather, but it doesn’t do so well with impact resistance. Any sharp impact could potentially break one of your stone tiles. One of the weird little quandaries of the universe is the fact that the hardest materials are sometimes the easiest to break. As the ancients learned, that which is hard without being flexible will invariably be brittle, and slate rock is a perfect example of that fact.
The good news here is the fact that slate will resist the impact of hailstones, even if they are large hailstones. Studies have confirmed this fact, but anything stronger than a hailstone is likely to crack or shatter these types of roofing tiles.
Even a careful roofer might accidentally break some stone tiles while stepping on them. They just don’t have any flexibility at all, so the weight of a human body is more than enough to make them chip, crack, or split. What’s worse, each slate tile has a slightly different size and shape. That is the case because slate is usually split along its natural grain, and that grain is rarely 100% straight. These small variations between tiles make it a serious pain in the neck when it comes to replacing shingles.
How Did Slate Become Popular As A Roofing Material?
You may be wondering why people started using slate for roof tiles in the first place. As we have already shown, stone tile has some significant advantages over the other options. However, you could get those benefits from almost any sort of stone. Why did they choose slate out of all the rocks in the world?
The answer is that slate is easier to split than most others. Like wood, all stone has a grain structure, and this affects the way that the substance will break. In the case of slate, its grain goes long-ways down the length of the stone, much like a straight piece of wood. Thus, this is one of the few stones that can be neatly split into small, flat pieces in the same way that you could do with a block of wood.
Conclusion
Slate roof tiles may not be the perfect option for everybody, but they do offer a unique and appealing range of benefits. If well maintained, a slate roof should be the last roof that you ever need to buy. If you can afford them, we recommend them over most other options. Still, you need to understand all the pros and cons before making a decision. We hope that we have made that decision a little bit easier. If so, we hope that you will fill out the contact form below so that we can keep you updated at all times.
