Steep-slope coverings and flashing

One-line orientation

Above 2:12, roofs use overlapping coverings whose watertightness comes from lapping plus correct flashing, and the high-yield distinction is split shakes (thick) vs sawn shingles (thinner).

Key points

• Steep-slope basics: slope > 2:12; sheds water/snow efficiently; more complex and costly to install than low-slope membranes.
• Shingles (e.g. asphalt):
  • Pros: economical, easy to install and repair.
  • Cons: shorter lifespan, more maintenance.
• Shakes:
  • Split from the wood, so thicker than shingles with a rugged, natural look.
  • Pros: natural appearance, durable.
  • Cons: need skilled installation, higher cost, and maintenance for mold and rot.
• Flashing at walls: step flashing — overlapping L-shaped metal pieces woven into the courses where a sloped roof abuts a vertical wall, lapping shingle-over-flashing-over-shingle.
• Tile and slate may be heavy and long-lived. Metal is also durable but is generally a lightweight covering.
• Weight comparison: metal roofing is relatively light; natural slate is much heavier.

Confusions / comparison

Covering	How made / form	Pros	Cons
Asphalt shingles	Manufactured, uniform sheets	Cheap, easy to install/repair	Shorter lifespan, more upkeep
Wood shingles	Sawn — thinner, uniform	Cleaner, more regular look	Wood upkeep; combustibility concerns
Wood shakes	Split — thicker, textured	Natural look, durable	Skilled install, costlier, mold/rot upkeep
Tile / slate	Lapped units	Long lifespan, durable	Often heavy; check structure
Metal	Panels or sheets	Durable; relatively light	Weight varies by full assembly

Related

→ Roof slope and drainage (this topic): the 2:12 low/steep dividing line · Roof flashing and terminations (this topic): coping, base vs counterflashing, vents · Low-slope membranes (this topic): the membrane alternative below 2:12.