Learn More About Asphalt Shingle
Asphalt shingle categories
| Type | What it is | Pros | Considerations | Typical lifespan* |
|---|---|---|---|---|
| 3-Tab | Single flat layer; notched to look like 3 tabs | Lowest cost, light weight, clean look | Shorter life, lower wind/hail resistance | 15–25 yrs |
| Architectural | Two+ bonded layers with varied shapes | Better curb appeal, thicker, higher wind ratings, best value | Heavier, mid-price | 25–35+ yrs |
| Designer | Extra-thick laminates that mimic slate/cedar | Premium look, longest shingle life, very high wind ratings | Highest cost, heavy | 30–40+ yrs |
*Actual life depends on ventilation, installation quality and weather.
Which Components Influence Roof Lifespan?
The following elements affect roof longevity as much as the shingles themselves. Knowing these helps you understand what goes into a quality roof and why it matters.
Roof Deck
What is it
The roof deck (or sheathing) is the layer of wood panels fastened to the rafters/trusses. Common materials are OSB or plywood; older homes may have plank/board decking. A solid, flat, and dry deck is essential for proper shingle performance, wind resistance, and leak prevention. Rotten or soft areas are replaced before installation. Manufacturers require a sound, nailable deck for warranty coverage.
Why it matters
- Nail holding & wind resistance: Shingles only perform to spec if nails bite into a solid, dry, code-rated deck.
- Flat, smooth surface: A flat deck lets shingles seal properly and look right (no waves).
- Leak prevention: Rotten/soft spots let fasteners loosen and water find its way in.
- Warranty & code: Manufacturers require a sound, nailable deck; many warranties are void if it isn’t.
Best practice when replacing a roof
- Full tear-off to bare wood so the deck can inspect everything.
- Replace any rotten/soft sections.
- Choose the right sheathing & thickness for your framing:
- Typical: 7/16" OSB on 16" O.C. trusses/rafters (good value).
- Upgrade: 1/2" plywood for added stiffness and moisture resilience.
- Wider spans/uneven framing: 5/8" (OSB or plywood) is often the better call.
- Only cover a dry deck; then apply ice & water at eaves/valleys/penetrations and synthetic underlayment over the rest.
Ventilation
What is roof/attic ventilation?
A proper attic ventilation system allows cool, dry air to enter at the eaves (intake) and warm, moist air to exit at the ridge (exhaust). Balanced airflow extends shingle life, reduces ice dams, controls moisture, improves energy efficiency, and is required by both code and manufacturer warranties.
Why it matters
- Longer shingle life: lowers attic temps so shingles don’t “cook.”
- Fewer ice dams: colder, drier attic = less melt-freeze at eaves.
- Mold & moisture control: moves humid air out before it condenses on wood.
- Energy efficiency: reduces AC load in summer and protects insulation performance in winter.
- Warranty/code: manufacturers and building codes require a vented attic on shingle roofs.
Best Option
Balanced attic airflow: continuous soffit intake (vents under your eaves) brings in fresh air, while a continuous, baffled ridge vent at the roof peak lets hot, moist air out, without letting wind-driven rain or snow in.
Starter shingles
What are they
The first row of shingles at the eaves and rakes, with an adhesive strip to lock down the edges and prevent wind uplift. They also create a straight starting line and improve water control.
Why they matter
- Stops wind uplift: the adhesive “locks” the shingle edges, preventing blow-offs.
- Straight, clean edge: gives a perfectly straight line to start the roof.
- Better water control: helps keep wind-driven rain from getting under the first course.
Best Option
Factory starter strips (often required for warranty)
Ice & Water Shield
What is it
A self-adhesive, waterproof membrane for leak-prone areas such as eaves, valleys, and around roof penetrations. It self-seals around nails, blocking water from ice dams and wind-driven rain.
Why it matters
- Blocks ice-dam leaks: When snow melts and refreezes at the eaves, water can back up under shingles. This membrane is waterproof and self-seals around nails, so backed-up water can’t sneak in.
- Stops wind-driven rain: Great defense in valleys and around penetrations.
Best Option
A peel-and-stick waterproof layer at the eaves, valleys, and roof details that self-seals around nails to prevent leaks from ice dams and wind-driven rain.
Synthetic Underlayment
What is it
A tear-resistant layer covering the rest of the roof deck under shingles. Works with Ice & Water Shield for maximum leak protection. Options include standard synthetic, high-temperature, and breathable types.
Why they matter
A durable, tear-resistant layer installed over the entire roof deck that helps shed water and protect the wood beneath your shingles. Used together with Ice & Water Shield at critical areas for maximum leak protection.
Options
- Standard synthetic underlayment (great value for shingle roofs).
- Premium/high-temp synthetic (for dark roofs, hot exposures, or under metal details).
- Breathable synthetics (special cases; usually for metal roofing assemblies).
What is the difference between the Ice & Water Shield and the Synthetic Underlayment?
The ice & water shield is a waterproof membrane for leak-prone spots and the synthetic underlayment is a breathable, water-shedding layer that covers the rest of the deck under the shingles. Both are typically use on a roof.
In Ottawa’s climate, the ice & water shield required by code. However, in some case it can be useful to install it in a larger section, such as a low-slope roof.
Metal flashings
What are they
Custom-bent metal pieces that direct water away from vulnerable areas such as edges, walls, chimneys, and vents. Critical for long-term leak prevention and warranty compliance
Why they matter
- Direct water into gutters and off the roof
- Block wind-driven rain at joints and seams
- Protect vulnerable transitions (edges, walls, chimneys, vents)
Best Option
Custom-bent metal at roof edges, walls, valleys, and penetrations that channels water into the gutter and away from your home, critical for long-term leak protection and manufacturer warranty.
Ridge Vent
What is it
A continuous vent along the roof peak that releases hot, moist attic air, working with soffit vents for balanced airflow. Reduces heat buildup, prevents ice dams and mold, and helps shingles last longer.
Why it matters
- Reduces heat and moisture buildup: helps shingles last longer, prevents ice dams/mold, improves energy efficiency.
- Warm air rises and exits at the ridge vent while fresh air enters through soffit (eave) vents. Balanced intake & exhaust is key.
Best Option
A continuous vent at the roof peak that lets hot, moist attic air escape, helping prevent ice dams, mold, and premature shingle aging. Works with soffit vents for balanced airflow.
Ridge Caps
What are they
Pre-formed shingles that seal and protect the ridges and hips, providing weather protection and a finished look.
Why they matter
Weatherproof the ridge, protect fasteners, and give a clean, finished look.
Best Option
Pre-formed shingles that seal and finish the roof peak (and hips), protecting against wind and rain and delivering a polished look.
Skylights
What are they
Roof windows that bring in natural light and ventilation. Must be installed with manufacturer-specific flashing kits to ensure watertight integration with roofing materials.
Why they matter
Skylights brighten interior spaces, improve energy efficiency by reducing lighting needs, and can add ventilation to help control moisture. Without proper installation and flashing, though, they can be a major leak risk.
Best Option
Energy-efficient skylights installed with manufacturer-specific flashing kits. This ensures a watertight seal, proper integration with roofing materials, and long-term performance.
Ottawa Climate
In Ottawa, Ice & Water Shield is installed at eaves and valleys by code, with synthetic underlayment elsewhere. A ridge vent and matching ridge caps are recommended for warranty compliance and maximum roof life.