FAQ

Looking for a slate roofing contractor?
We work with the top “slaters” to ensure quality installation from slate roofing repairs, restoration or new construction. Our recommended list of slate roofers have the knowledge and craftsmanship to meet your project’s needs. Contact our office or complete a Request Information form to tell us about your project and we will be in touch with information about experienced slate roofing contractors near you.
What sizes of roofing slate are available?

The standard sizes for roofing slate start at 12″ in length and increase by 2-inch increments up to 24″ in length. The standard widths are never less than half their length (12×6, 14×7, 16×8, 18×9, etc.) and increase by 1-inch increments up to 14″ wide. Additional lengths and widths are also available.

SCHEDULE OF STANDARD SIZES

Slate size Pieces per square Exposure
Inches at 3″ headlap at 3″ headlap
24 x 12 115 10.5″
22 x 12 126 9.5″
22 x 11 137 9.5″
20 x 14 121 8.5″
20 x 12 141 8.5″
20 x 11 154 8.5″
20 x 10 170 8.5″
18 x 14 137 7.5″
18 x 12 160 7.5″
18 x 11 175 7.5″
18 x 10 192 7.5″
18 x 9 213 7.5″
16 x 14 158 6.5″
16 x 12 185 6.5″
16 x 11 201 6.5″
16 x 10 222 6.5″
16 x 9 246 6.5″
16 x 8 277 6.5″
14 x 12 218 5.5″
14 x 11 238 5.5″
14 x 10 262 5.5″
14 x 9 291 5.5″
14 x 8 327 5.5″
14 x 7 374 5.5″
12 x 10 320 4.5″
12 x 8 400 4.5″
12 x 6 534 4.5″
How much does a slate roof cost? We are often asked by designers, architects, home and building owners “What will a slate roof cost me”?
On average, North American produced S-1 rated roofing slate will cost $400 – $600 USD per square (100 square feet) or $4.00 to $6.00 USD per square foot for a standard thickness 1/4”-3/8” roof. Color, size and availability are all contributing factors to this range of roofing slate material costs. Historically, semi-weathering gray/green (Sea Green) has been one of the less expensive slates, due to its easy working characteristics and the relative abundance of stone deposits; while unfading red, due to its difficult working characteristics and relative rarity, can range upwards to over $1,000 USD per square. In general, the cost of weathering or semi-weathering slates are less expensive than unfading slates, although both will give comparable service life. The cost of transportation of roofing slate from the producer to the job site must also be taken into consideration. These costs may range from $15 – $80 USD per square depending on quantity shipped, the distance to destination and access to the job site. The delivery of a quality, North American produced, S-1 rated roofing slate to your job site at this point will yield a roof with a minimum service life of more than 75 years and represents a solid, cost effective and aesthetic investment in your building. Once the slate has arrived on site, the cost of installing a slate roof system by a qualified contractor depends on a number of factors, including roof complexity, roof pitch, accessibility, the details of hips, ridges and valleys, flashing materials and regional wage, insurance and benefit variations. Installation costs on a simple gable to gable roof with few or no roof penetrations may cost $15 USD per square foot. Installation on a more elaborate and complex roofscape may cost $30 USD per square foot or more. Having a qualified slate roofing contractor install your slate roof system including underlayment, ice dam protection membrane, flashing and valley metal, drip edge, slate, gutters and downspouts will be the key to your 100 year roof. These are the people who can assess your roof or roof plans and give you a budget price for the installed cost of a complete roof. Should natural roofing slate be outside your budget, these same roofing contractors can recommend suitable alternatives for your building. North Country Slate would welcome the opportunity of providing you with information on our natural roofing slate products and we would be pleased to refer qualified slate contractors in your area to you to get you started on your way.
What minimum roof pitch is required in order to utilize slate?
With special consideration for slate size, headlap and underlayment – natural roofing slate can be applied to roofs with a slope of four inches per foot.
What roof decking is required for the application of slate?
One inch board sheathing or 3/4″ APA plywood provides a suitable deck material for the installation of natural slate. This material provides minimum deflection during nailing, supports the weight of the slate between rafters and provides adequate resistance to nail pull out.
What weights should be taken into account when considering natural slate?
The weight of nominal 3/16″ slate is 7 – 8 lbs. per square foot and nominal 1/4″ is 9 – 10 lbs. It is worth noting that the common practice of applying 3 layers of asphalt shingles, before tearing off, creates a combined total weight of 7+ lbs. As with the application of any roofing material, dead load weights for natural roofing slate should be taken into consideration at the design stage or prior to re-roofing.
What climatic restrictions apply to the use of natural slate?
Good quality natural roofing slate has been used under the harshest climatic conditions in the world and has proven performance dating back a thousand years. Poor quality roofing slate yields a limited life expectancy under moderate conditions and therefor its use should be restricted to milder climates with very careful evaluation of precipitation and freeze thaw cycles.
Can you suggest a competent slate roofing contractor who can supply the slate and install my roof?
We maintain a database of qualified North American roofing contractors who have the necessary skills and experience to install your roof. With some basic information regarding your roofing requirements, we can recommend the contractors that are most capable and interested in your type of project.
How long can I expect a slate roof to last?
The life expectancy of a slate roof will depend on climatic conditions, roof pitch and slate quality. Climatic conditions and roof pitch are variable, however, ASTM International’s C406 Standard Specification for Roofing Slate establishes expected service life for grades of slate as S1 over 75 years, S2 40-75 years and S3 20-40 years..
How many nails will I have to order?
Typically, each piece of slate is punched with two nail holes. In most cases, nails are ordered by the pound. Please check out this resource which will show the pounds per square required based on the size of slate tile.
What are slate roofs?
Essentially a slate roof is a stone roof! Slate roof tiles are made of metamorphic rocks which are derived from sedimentary rock of volcanic ash and clay. Created by the forces of nature over 500 million years ago, slate roofs have provided shelter to homes, churches, courthouses, universities and historic buildings for more than a thousand years. As a natural product, no two pieces of slate are the same. There will be a variation in shade, veining, texture and grain. Being a natural stone they are environmentally friendly and don’t give off volatile organic compounds (VOCs) or other pollutants.
If you’re missing a few slate shingles do I need to replace the entire roof?
The rule of thumb is if 20-30% of the slates are damaged, it’s better to replace the entire roof. If it’s just a few pieces, a skilled slate roofer will be able to match the existing color, size and thickness and with a copper repair hook can slide the new piece back into place.
How much does slate weigh?
Slate is available in several thicknesses depending on the supplier. The weight is based on the pounds per square. One roofing square covers 100 square feet. The most common thickness is 1/4” to 3/8”.
  • 3/16” (675-700 LBS)
  • 3/16” – 1/4” (820 LBS)
  • 1/4” (935 LBS)
  • 1/4” – 3/8” (1170 LBS)
  • 3/8” (1405 LBS)
  • 1/2” (1870 LBS)
Where does slate come from?
Roofing slate is actively produced from high quality North American quarries located in Vermont, New York, Virginia and Quebec, Canada
What is the price difference between unfading and semi-weathering slate?
Natural roofing slates are classified based on their weathering characteristics. Please note that a semi-weathering slate is not inferior to an unfading one, the weathering characteristics of a slate has to do with its chemical and mineral composition. The price may vary slightly depending on the color, size and availability. The most expensive roofing slate is an unfading red due to its limited availability and production.
Where to buy slate roof tiles?
If you are reading this then you’ve come to the right place! Buying a slate roof can be one of your most expensive purchases, but also a wise one when you consider how long they last. Keep in mind, not all slates are created equally. Do your research as slate can come in three different grades. Slates should be tested by the quarry or slate supplier to ensure they meet the ASTM testing requirements. An S-1 slate will last over 75 years, a S-2 will provide a service life of 40-75 years and an S-3 will last 20-40 years. Some S-1 slates have lasted well over 100 years! With that said, you may be enticed with foreign slate pricing. Ask the supplier for up to date ASTM test results to ensure you are getting a good quality slate.
What kind of Slate roof underlayment is necessary?
Traditionally, a slate roof will have #30 (thirty-pound) asphalt saturated organic felt unperforated roof underlayment. Required by many building codes, a slate roof’s underlayment serves many purposes and application may vary depending on thicknesses of slate, weather conditions of the area and size of slate. Order an extra 10% of underlayment to account for overlaps and waste. Underlayment is sold by squares similar to roofing slate. A 3’ x 72’ roll will cover 216 square feet which would cover 2.16 squares. You can see more of the slate roof underlayment process here.
Are slate roofs good?
Natural slate roofing has been used for hundreds of years and can last well beyond 100 years when installed properly using an ASTM S-1 rated roofing slate. Not only are they durable and long lasting, but they are also non-combustible (fireproof), unaffected by freeze/thaw cycles, environmentally safe, and can be made up of an assortment of colors with unfading and weathering characteristics.
How to remove slate roof tiles?
You will need a slate hammer and slate ripper. A slate ripper weighs 3 lbs and is made of carbon steel, including the handle it is 30.5” long. Once you have identified the piece of slate to be removed, slide the ripper under the slate tile. You may need to hit the ripper’s handle to reach the nails to be cut with the hook at the top of the ripper. Once the nails are cut, you will then be able to slide the slate out. Check out 3 tools you should invest in when installing and maintaining a slate roof
How is slate roofing made?
The Glendyne quarry that produces our North Country Unfading Black slate uses diamond wire, which is threaded onto a continuous wire loop that is passed round the area of slate to be extracted. Once the block has been wire sawn it is extracted from the rock face using a hydraulic pecker which is split into more manageable sizes. These blocks which can weigh over 5 tonnes are transported to the mill where they are marked by a trained quarry expert who determines the best potential size to be produced. The marked block then goes through the primary and secondary sawing department which cuts the block into more manageable slabs. The slabs then move onto the splitting department where they are split into approximately eight 1 ½’ thicknesses. The slates are then trimmed to the desired final size and the trimming machine removes the sawn edges and creates the bevelled edges. The final stage, the slate goes thru is grading and packing to ensure high quality controls. You can see more about how slate roofing is made here.
How are slate roof tiles attached?
Slate roof tiles are holed with two nail holes, located approximately 1/3 of the way down from the top of the slate and 1 ¼” – 1 ½’ in from each side. They are attached with copper nails (10 gauge) and typically smooth shank in the event they need to be repaired it’s easier to cut with a slate ripper. The required length of the nail will be twice the slate’s thickness plus an inch.You can read more about nails used on a slate roof here.
Can a slate roof be repaired?
Absolutely you can repair a slate roof! Sometimes a slate roof can be damaged by stress cracks, over nailing, foot traffic, fallen tree limbs and inclement weather.
A slate roof can last 100 plus years so when a few pieces or a section of the roof is damaged, it’s worth repairing. More importantly, finding an experienced contractor will ensure the repair is done properly and not repaired with a roofing cement which doesn’t last and makes future repairs difficult. An experienced slate roofer will be able to match the existing color, and identify the size and thickness.
The rule of thumb is if 20-30% of the slates are damaged, it’s better to replace the entire roof. Contact us for an experienced slate roof specialist in your area.
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I have never had anything except a 5 Star Experience when working with North Country Slate.

- ABC Supply, Outside Sales

When our clients are looking for a natural slate roof, we highly recommend North Country Slate.

- Raines Brothers, Inc.

We have used North Country black on a large number of occasions, and we’ve found it to be an excellent quality slate it is very “workable”.

- John Chan, The Durable Slate Company
Looking for a slate roofing contractor?
We work with the top “slaters” to ensure quality installation from slate roofing repairs, restoration or new construction. Read More
What sizes of roofing slate are available?
The standard sizes for roofing slate start at 12″ in length and increase by 2-inch increments up to 24″ in length. Read More
How much does a slate roof cost? We are often asked by designers, architects, home and building owners “What will a slate roof cost me”?
On average, North American produced S-1 rated roofing slate will cost $400 – $600 USD per square (100 square feet) or $4.00 to $6. Read More

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