A slate roof is king among all “forever” roofing materials, set far apart from the rest in terms of exceptional curb appeal, durability and long lasting service. It is no surprise that the average cost of slate starts at $20,000 plus
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Across Europe and US, slate tiles have been used to cover upscale homes and palaces for centuries. They have a time proven track record of resistance to severe weather, a service life lasting well over 100 years, and a classic look that never goes out of style.
In this guide:
How much does a slate roof cost?
On average, homeowners across US, report spending about $20,000-24,000+ to install slate roofing on a 1,600 sq.ft. house. When you consider the entire system, labor and old roof removal costs, you are looking to spend at least $1,500-4,000 per square.
Real slate is the most expensive building material, and there are a number of factors that contribute to this.
The quality (grade), thickness, color, and the amount of material required, greatly impact final prices. Larger jobs will cost less per square than smaller ones. The cost of the stone itself can range from $450-800 per square.
Installation charges also vary greatly, depending on the contractor, size and complexity of the job. You can expect to pay $650+ per square for a high quality installation.
If your existing roof framework will require additional reinforcement to support the weight of slate, this may add anywhere from $1000-10,000+ to the total job cost.
Remember that a roof has many critical components/materials, in addition to the stone itself! If you are already investing into such an expensive material, DON’T try to save on other parts of the system.
Just like you would not put used tires on a Bentley, don’t use sub-par materials for flashing, underlayment, etc. Saving money on these components will not significantly reduce the total price tag, but will definitely contribute to major and costly problems in the near future.
Here are the top reasons why people choose this classic material over more modern and modestly priced roof types.
1. Superior protection: regardless of the weather conditions prevalent in your area, you can be sure that slate will protect your home! This roof is completely resistant to wind, snow, rain, sun, hot and cold fluctuations.
2. Impervious to water: leaks large and small are a serious issue for the majority of roofing materials. However, being a stone, slate will remain 100% leak free for the duration of its life (provided proper installation techniques and high quality materials for other parts of the roofing system have been used).
3. Exceptional Durability: the stone is highly resistant to mold, mildew, insect infestation, rust and other sources of damage that plague many other materials.
4. Longevity: it is one of the longest lasting materials. 1st grade stone can last over 200 years! In fact, there are many instances, where the entire house is destroyed, and the roof is the only thing that remains in tact.
5. Fire Proof: this material will never catch fire.
6. Custom Look: you can order it in a countless array of lengths/widths/thicknesses, different tile patterns, and a variety of installation types. It can compliment almost any architectural house style.
7. Easy Maintenance: unless slate tiles crack or break (requiring replacement) you can enjoy a virtually maintenance free service life for many years to come.
8. Environmental Benefits: this is a green building material. Over the course of its lifetime it can help lower your energy costs and conserve resources required for frequent roof replacement.
9. Increase Home Value: superb curb appeal, combined with the fact that it is a “lifetime” roof can add great value to your house and attract more buyers.
Here is a run down of the most significant slate disadvantages.
1. Brittle: this means it can easily crack and break during installation or a repair job. Falling tree branches, thrown stones or large hail can also cause it to crack, warranting replacement of the damaged tiles.
2. Exceptionally heavy: slate weighs from 8 to 15 pounds per square foot. Many existing house structures are not built to withstand such a heavy load. It is important that you structurally evaluate your residence to make sure it is an appropriate fit for slate installation. If your roof is not properly built, you will need to upgrade the framing to support the roof load, as well as snow (if you live in the Northern States). New construction homes can be specified to withstand the added structural load of with extra reinforcement.
3. Long job completion time: unlike most other roofing materials, slate is not instantly available upon placing your order. It may take as long as 1-3 months for your materials to arrive to the job site. Furthermore, because of the difficult and tedious installation process, completing the install also takes a long time.
For an average home size, you can expect the job to take up to 3 months (if you hire a professional slater, who will not skip on crucial installation procedures). In rare cases, very large jobs (around 170 roof squares) that have many obstacles on the roof (dormers, valleys, chimney, etc) and require graduated, textural patterns can take up to 1 year!
4. Challenging tile replacement: if you will need to replace broken tiles, it will be essential to get the right size, shade and texture, which match the existing roof.
5. Lack of professional installers: slate tile installation is an intricate balance of art and science. As a result, there are only a handful of expert roofers who can do the job right. Many homeowners fall prey to unprofessional contractors who claim to know this trade and end up doing a lot of damage that costs thousands of dollars to fix. To avoid this problem, consult the National Slate Association to find an expert slater in your area.
Slate used on roofs can be divided into two types: hard and soft. Generally, hard varieties last 75-200 years, while soft ones last 50-125 years. Another distinct characteristic is that hard slate is almost always colored, while the soft one is almost always black.
These stones can come in a variety of thicknesses. The standard, most common size is about 3/16″ – 5/16″. However, many roof designs call for thicker pieces, and other sizes are 3/8″ – 1/2″, 1/2″ – 3/4″ or even 3/4″ – 1″ or more. Obviously, thicker tiles will be a lot more expensive than the standard size.
In fact, because these roofs are so good looking and long lasting (but unfortunately expensive), metal roofing manufacturers have created various metal shingles profiles that look similar to slate.
What color is slate?
Slate color pallet is arrestingly beautiful. Because its 100% natural, no pigments are ever added to enhance or alter the existing color. There are beautiful shades of green, grey, brown, purple and black.
When looking at the stone, you will notice that there are no separate, discrete colors. Instead, there are hues that gradually flow into one another. As with anything produced by Mother Nature, no two stones will have the exact same color.
Two types of colors
Color slate can be divided into two categories: unfading (permanent) or weathering.
Permanent shades will remain the same over the years; they will NOT fade.
Weathering shades may change to brown, rust, or grey on the exposed surface. However, the original color can still be determined by looking at the inside of the broken stone.
If you want something really special, is is possible to get true Unfading Red color slate. This is the most expensive stone available, and the price tag is reflective of the limited deposits and challenging production procedures. Produced in Washington County, New York, Unfading Red is also one of the most durable varieties.
Repair and replacement considerations
Just like all materials, slate will eventually age, break, leak, etc. At that point you will need to decide whether to repair or replace your roof. Choosing one or the other will largely depend on the type of slate your roof is made of.
As we discussed in the beginning, there are soft and hard varieties. If you are not sure which type you have, you need to seek advice of an expert “slater”.
If you have the hard type and it is leaking (even if it is already 100 years old), it may make sense to fix and restore, because you can get another 100 years of service out of it. However, if its soft slate, and the roof is already very old, it may not be worth repairing, as it is already nearing the end of its service life.
To avoid putting your home at risk and wasting a lot of time and money, be sure to work only with a professional slater for both repair and replacement jobs. While slate is supposed to last for centuries, at the end of the day it is only as good as the roofer who installs it.
Slate vs. asphalt shingles
There is no fair way to compare roofing shingles to slate, with the former being the cheapest, most common material, and the latter being the most high-end, exclusive product.
Asphalt shingles are best suited for homeowners who are price-conscious and are not looking for the most long lasting and durable material. A basic asphalt roof can cost as little as $5,000. On the down side, this low cost is associated with frequent leaks, poor weather resistance, short life span (12-20 years) and often sub-par installation quality. On the up-side, repairs and replacement are quick, cheap, and there are plenty of roofers to do the job.
Comparatively, money is not a concern for people who want slate on their roof. They are willing to pay top dollar for the premium quality and prestige of this material.
When it comes to environmental considerations, asphalt shingles are not a green option. They are made of petroleum byproducts, require a lot of energy during the manufacturing process, and typically do not save on energy costs for the home. An asphalt roof also needs to be landfilled at the end of its service life, further exacerbating existing pollution problems.
Slate, on the other hand, is very environmentally friendly. It is 100% natural, and its long service life eliminates the need for frequent replacement, avoiding the wasting of precious resources. Moreover, it can be recycled at the end of its service life.
Where does slate come from?
Slate is one of the few completely natural building materials. It takes tens of thousands of years of sediment to form 1″ of stone! This explains why it is also one of the most expensive roof coverings.
Essentially, slate is a metamorphic rock that formed under intense heat and pressure, deep below the earth’s surface. Due to a particular formation process, it has a unique parallel alignment of the minerals that allows it to be separated into layers (split).
Slate is retrieved from quarries. This is a difficult and labor-intensive process, where only 10% of the handled stones ends up as a finished product. In the USA, active quarries are located in Vermont, New York, Pennsylvania and Virginia.
During the manufacturing process, the stone is hand-split using a hammer and chisel. This procedure requires precision and great craftsmanship. In fact, special splitting techniques (secrets) are passed down from generation to generation.
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