BuildCompared

Slate Roof vs Shingles

Slate is stone, and it is heavy: one producer lists its grades from 680 to 780 lb per square (thinnest grade) up to 2,500 to 3,000 lb (thickest), while CertainTeed's Landmark asphalt shingle weighs 217 to 229 lb per square (100 square feet).[1, 2] Slate also needs a steeper roof, 4:12 against 2:12.[3] Roofing slate is graded S1, S2 or S3, each with its own breaking load, absorption and depth-of-softening limits.[4]

Sources checked How we compare

Natural slate

Slate roof: individual stone slates laid in staggered courses
Individual stone slates

Pick slate if the structure can carry the weight, the slope is 4:12 or steeper, and you want natural stone with a graded service class.[1, 3, 4]

Asphalt shingles

Architectural shingles: two laminated layers with tabs of different sizes
Laminated asphalt shingles

Pick shingles if you want a much lighter roof, or the slope is under 4:12.[2, 3]

At a glance

Natural slateAsphalt shinglesSource
Weight per square (100 sq ft) Greenstone Slate: 680 to 780 lb per square (thinnest grade) up to 2,500 to 3,000 lb (thickest) CertainTeed Landmark: 217 to 229 lb per square (100 square feet) [1, 2]
Minimum slope in the code 4:12 2:12 [3]
Material standard in the code ASTM C406 ASTM D3462 [3]
Grading S1, S2 or S3, each with its own breaking load, absorption and depth-of-softening limits Wind classes: GAF Timberline HDZ ASTM D3161 Class F and ASTM D7158 Class H [4, 5]
Expected life or warranty (examples) Greenstone: S1 slate is rated to last at least 75 years; 100-year guarantee GAF architectural: Lifetime, 10 years non-prorated [1, 6]

Weight

Slate weight depends on thickness. Greenstone Slate lists its thinnest grade at 680 to 780 lb per square and its range at 680 to 780 lb per square (thinnest grade) up to 2,500 to 3,000 lb (thickest).[1] CertainTeed lists Landmark shingles at 217 to 229 lb per square (100 square feet).[2] A house built for shingles may need its structure checked before it carries slate.

Grades

ASTM C406 sorts roofing slate as S1, S2 or S3, each with its own breaking load, absorption and depth-of-softening limits.[4] Producers advertise the top grade with a service life: Greenstone says S1 slate is rated to last at least 75 years, and offers a 100-year guarantee.[1]

Slope and standards

The residential code allows slate from 4:12 and asphalt shingles from 2:12. Slate must meet ASTM C406; shingles ASTM D3462.[3]

Cost

We did not find a neutral, published installed-cost comparison for slate and shingle roofs, so this page does not show one.

Common questions

How heavy is a slate roof?

One producer lists 680 to 780 lb per square (thinnest grade) up to 2,500 to 3,000 lb (thickest).[1]

What do S1, S2 and S3 mean?

They are the ASTM C406 grades: S1, S2 or S3, each with its own breaking load, absorption and depth-of-softening limits.[4]

What is the minimum slope for slate?

4:12 in the residential code.[3]

Sources

  1. Greenstone Slate Company Greenstone Slate brochure (Rev. ISVT-J11282-2016) (2016). Accessed November 3, 2026.
  2. CertainTeed Landmark Shingles Technical Data Sheet (copy hosted by RCABC) (03/23). Accessed November 3, 2026.
  3. California Building Standards Commission 2025 California Residential Code, Section R905 Requirements for Roof Coverings (effective January 1, 2026). Accessed November 3, 2026.
  4. ASTM International C406/C406M-22 Standard Specification for Roofing Slate (2022 edition). Accessed November 3, 2026.
  5. GAF Timberline HDZ Shingles spec sheet (RESGN467HDZ) (January 2026). Accessed November 3, 2026.
  6. GAF GAF Shingle & Accessory Limited Warranty (RESWT160L) (Form RESWT160L-0426, for installations after January 1, 2025). Accessed November 3, 2026.

We did not install or test these products. Everything on this page comes from the documents listed above. If a source changes, numbers here may be out of date until our next check. Spot an error? Email [email protected].