Slate Roof Information

Technical Bulletins

Reuse Of Slate Shingles Exposed To Fire

Recent research has confirmed that slate is not flammable and does not create or emit toxic substances when exposed to fire. The remaining question, which comes up periodically, is: can slate that has been exposed to fire be salvaged and reused?

Nail Holes In Slate

Each natural roofing slate is typically installed with a minimum of two nails. Learn more why slate comes from the quarries the way it does.

Vertical Joint Spacing

Vertical joint spacing refers to the amount of space between two adjacent slates within the same course. Learn more how it affects the roof.

Lesser Known Slate Deposits

Between 1879 and 1957, quarries in the principal commercial slate deposit regions produced 83.5 percent of total U.S. output (roofing and structural slate). What is less well known is where the other 16.5% of U.S. slate production came from.

Checking Roofing Slate Deliveries

It is always prudent to review the slate received prior to beginning installation to make sure it meets the requirements of the purchase order placed with the supplier, confirm quantities received, and record any obvious damage to pallets or product during transportation.

Common Myths About Slate Roofing

Slate shingles are a natural product with exceptional durability and aesthetic beauty. They have been in use in North America for over 400 years. During this time, certain myths have developed around the product. The purpose of this Technical Bulletin is to address some of the more common myths with factual information.

Historic Production Data

This Technical Bulletin pulls together information from various sources in an attempt to provide a meaningful window into the long and venerable history of the United States roofing slate industry.

Dutch Lap Slate Roofing

The Dutch Lap method of installing slate can be defined as a lightweight method in which the slates are laid with a side lap and single lap at the heads of the slates.

Slate Roof Condition Assessment Surveys

In assessing the condition of slate shingles, it is helpful to have knowledge of the type of slate present on the roof and the date the shingles were installed. This information, combined with knowledge of the estimated service life of the slate, can provide an insight into the expected remaining service life of the roof.

Corrosion and Wear of Metal Flashings

Slate roofs rely on metal flashings at critical junctures. When leaks develop in slate roofs, it is often due to flashings that have worn out. Understanding what causes the flashings to wear out, and proper detailing to address these problems, can improve the function of slate roofs, and defer the need for costly repairs. C

Natural Slate Vs. Synthetic Imitations

The fact is, no synthetic shingle has ever achieved a service life of 50 years, not to mention that of a S1-grade slate (75 years or more).

Technical Information

NSA Safety Data Sheet

The Safety Data Sheet was developed and undertaken to provide National Slate Association members with a generic Safety Data Sheet covering North American produced natural roofing slate based on the average mineral and chemical makeup of the roofing slate produced by North American quarries.

Slate Hail And Fire Test

The testing was conducted on North American produced S-1 rated natural roofing slate by Architectural Testing of Southlake, Texas, in accordance with Factory Mutual FM 4473, Specification Test Standard for Impact Resistance Testing of Rigid Materials by Impacting with Freezer Ice Balls.

Slate Testing Labs

Testing slate roofing materials to ensure that standards are met is important to everyone. However, the National Slate Association has found that there can be significant variation in test results from some slate testing labs. Therefore we offer the below list of NSA-recommended slate testing laboratories.

Pallet Card For Slate Installation Wind Test

Asphalt shingles have long included basic installation instructions on the wrappers—the NSA Pallet Card, adapted from the NSA’s Slate Manual, performs the same service for slate installation. It is a weather-proof sheet, stapled to the slate pallets, that uses text and diagrams to illustrate basic procedures, such as shuffling slate, eave and valley lay-out, etc.

Professional Roofing Red Slate Article

Built in 1892, the Old Red Museum of Dallas
County History and Culture is a symbol of Dallas heritage.
Located at the crossroads of tourist traffic, the museum
is adjacent to the John F. Kennedy Memorial and Dealey
Plaza. Seeking to inspire and educate people about the rich
cultural, economic, political and social history of Dallas,
the museum showcases many cultures that formed the

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