Asphalt Shingle Roofing Guide

Complete guide to asphalt shingle roofing installation including underlayment types, shingle grades and warranties, nailing patterns, starter strips, ridge cap installation, valley methods, and proper ventilation requirements.

Shingle Types & Warranty Grades

Understanding Shingle Quality

Asphalt shingles are rated by warranty length, weight, and wind resistance. Higher-grade shingles last longer, resist wind better, and often have better aesthetics. The warranty period directly correlates with thickness and durability.

3-Tab Shingles

Basic, economical option

• Warranty: 20-25 years
• Weight: 200-250 lbs per square
• Wind rating: 60-70 mph
• Appearance: Flat, uniform pattern
• Cost: $80-120 per square
• Best for: Budget projects, rentals

Architectural/Dimensional

Premium/Luxury

Highest quality

• Warranty: Lifetime limited warranty
• Weight: 400-480 lbs per square
• Wind rating: 130+ mph
• Appearance: Ultra-dimensional, designer
• Cost: $200-400+ per square
• Best for: High-end homes, curb appeal

Special Features to Consider

Algae resistant: Copper or zinc granules prevent black streaks (add $5-15 per square)
Impact resistant (Class 4): UL 2218 rated, insurance discounts in hail areas
Cool roof rated: Reflective granules reduce heat, energy savings in hot climates
Enhanced wind resistance: SBS modified asphalt, higher nail strip adhesive
Warranty transferability: Some limited lifetime warranties transfer to new homeowner

Underlayment Selection

15 lb Felt (Tar Paper)

Traditional option

• Type: Asphalt-saturated organic felt
• Cost: $15-25 per roll (400 sq ft)
• Installation: Staple or nail down, 2" overlap
• Pros: Inexpensive, breathable
• Cons: Tears easily, limited water resistance
• Best for: Budget reroof, low-slope areas

30 lb Felt

Heavier duty felt

• Type: Thicker asphalt-saturated felt
• Cost: $25-40 per roll (200 sq ft)
• Installation: Staple or nail, 2" overlap
• Pros: More durable than 15 lb, better water resistance
• Cons: Heavier, still tears, wrinkles
• Best for: Steep slopes, temporary weather protection

Synthetic Underlayment

Modern standard

• Type: Woven or spun polypropylene
• Cost: $50-90 per roll (1000 sq ft)
• Installation: Plastic cap nails or staples, 4" overlap
• Pros: Tear-resistant, slip-resistant, UV stable
• Cons: Higher cost than felt
• Best for: New construction, quality projects

Ice & Water Shield

Self-adhering membrane

• Type: Rubberized asphalt, peel-and-stick
• Cost: $60-100 per roll (200 sq ft)
• Installation: Self-adhering, 6" overlap
• Pros: Waterproof seal, self-heals around nails
• Cons: Expensive, can trap moisture if overused
• Required: Eaves, valleys, penetrations, low-slope

High-Temp Ice & Water

For metal and dark roofs

• Type: Higher temp tolerance membrane
• Cost: $80-120 per roll (200 sq ft)
• Installation: Peel-and-stick, 6" overlap
• Pros: Won't bubble in extreme heat
• Cons: More expensive
• Best for: Metal roofs, dark shingles, southern climates

Breathable Synthetic

Vapor-permeable option

• Type: Micro-perforated polypropylene
• Cost: $60-100 per roll (1000 sq ft)
• Installation: Plastic cap nails, 4" overlap
• Pros: Allows moisture to escape from attic
• Cons: Higher cost
• Best for: Cathedral ceilings, no attic ventilation

Underlayment Installation Requirements

Eaves (ice dam protection): Ice & water shield from eaves to 24" inside warm wall (entire eave overhang + 24")
Valleys: 18" wide centered on valley, or full ice & water shield
Penetrations: Ice & water shield around chimneys, skylights, vent pipes
Field: Synthetic or felt underlayment over entire roof deck
Overlap: Horizontal laps 2-4", vertical laps 6", stagger end laps
Fastening: Just enough to hold until shingles installed (don't over-fasten)

Nailing Patterns & Requirements

Critical Nailing Rules

Proper nailing is essential for shingle performance and warranty validity. Improperly nailed shingles will blow off in wind, void the warranty, and cause leaks. Always follow manufacturer specifications exactly.

Standard Nailing Specifications

Shingle Type	Nails Per Shingle	High Wind Areas	Nail Location
3-Tab Shingles	4 nails	6 nails	5/8" above cutouts, 1" from ends
Architectural/Dimensional	4 nails minimum	6 nails	Through nailing strip, 1" from ends
Premium/Luxury	4-6 nails (per specs)	6 nails minimum	Check manufacturer specs
Starter Strip	3-4 nails per shingle	Every 12" minimum	3-4" from eave edge, above seal strip
Ridge Cap	2 nails per cap	2 nails (both sides)	1" from each edge, 5 1/2" exposure

Proper Nailing Technique

Nail type: Roofing nails, 1-1/4" minimum (1-1/2" for thick decking)
Nail head: 3/8" to 7/16" diameter minimum
Material: Galvanized steel or aluminum (rust-resistant)
Depth: Flush with shingle surface (not overdriven)
Angle: Perpendicular to roof deck (90°), not angled
Spacing: Follow manufacturer's nailing line precisely

Common Nailing Mistakes

High nailing (above nail line) - shingles blow off
Overdriven nails (cut through shingle) - creates holes
Underdriven nails (nail head above surface) - tears shingles
Angle nailing (not perpendicular) - poor holding power
Missing deck entirely - no hold, will fail
Too few nails - voids warranty, wind damage

Wind Zone Requirements

Normal wind (under 110 mph): 4 nails per shingle standard pattern
High wind (110-150 mph): 6 nails per shingle, hand-seal tabs with roofing cement
Hurricane zones: 6 nails minimum, use high-wind shingles with enhanced sealant
Coastal areas: Stainless steel nails recommended (salt air corrosion)
Steep slopes (over 60°): 6 nails plus hand-sealing with cement

Starter Strips & Ridge Cap Installation

Starter Strip Installation

Starter strips provide a solid base for the first course and seal the eave edge to prevent wind-driven rain and uplift.

Purpose: Fills gaps between shingle tabs at eave
Options: Dedicated starter, or field shingles cut/reversed
Overhang: 1/4" to 3/4" beyond drip edge (check code)
Adhesive: Must have sealant strip facing up toward eave
Nailing: 3-4" from eave edge, above sealant strip
Rakes: Install starter along rake edges too

Ridge Cap Installation

Ridge caps seal the peak and hip ridges, provide finished appearance, and ensure wind and water protection at the most vulnerable areas.

Options: Pre-cut ridge cap or field shingles cut into thirds
Exposure: 5" to 5-1/2" exposure typical
Direction: Install toward leeward side (away from prevailing wind)
Nailing: 2 nails per cap, 1" from each edge, 5-1/2" back from leading edge
Hips: Start at eave, work up to ridge
Final piece: Seal last ridge cap nails with roofing cement

DIY Starter Strip Method

If dedicated starter strips aren't available, you can create them from field shingles:

1. Take full 3-tab shingle and cut off the tabs (keep the top portion with sealant strip)
2. For architectural shingles, reverse the shingle so tabs point up toward roof
3. Install with sealant strip toward roof, overhanging drip edge 1/4"-3/4"
4. Nail 3-4" above eave edge, spacing nails every 12"
5. Ensure joints in starter course don't align with joints in first course of shingles

Valley Installation Methods

Valley Importance

Valleys channel the most water on a roof (water from two slopes converges). Proper valley installation is critical to prevent leaks. Always use ice & water shield in valleys regardless of climate.

Open Valley (Metal)

Most durable method

Material: 24" wide galvanized or aluminum valley flashing
Base: Ice & water shield 18" wide centered on valley
Flashing: Crimp center to form V-channel
Shingles: Cut back 2-3" from centerline on each side
Clip corners: Angle cut top corner to direct water
Pros: Longest lasting, easy to clean, fast water shed
Cons: Visible metal (aesthetics), higher cost

Closed Cut Valley

Woven Valley

Traditional method

Base: Ice & water shield 18-24" wide
Method: Weave shingles from alternating planes
Pattern: Each course crosses valley, alternates overlap
Nailing: No nails within 6" of valley center
Best for: Similar-pitch roofs, 3-tab shingles
Pros: Maximum coverage, no exposed membrane
Cons: Most labor-intensive, debris can catch

Valley Installation Rules

• Always install ice & water shield in valleys before any other underlayment
• Extend ice & water shield at least 18" each side of valley centerline (36" total width minimum)
• Never nail through valley within 6" of centerline (nails create leak points)
• For closed/woven valleys, use two layers of ice & water shield in snow regions
• Clip corners at 45° angle to prevent water from wicking under shingles
• Open metal valleys must have crimped center to prevent water from crossing

Roof Ventilation Requirements

Why Ventilation Matters

Proper attic ventilation extends shingle life by 20-30% by preventing heat buildup (which accelerates aging) and moisture accumulation (which causes rot and ice dams). Most shingle warranties require adequate ventilation.

Code Requirement: 1 square foot of net free ventilation per 150 sq ft of attic space (1:150 ratio), split 50/50 between intake (soffit) and exhaust (ridge/roof).

Ridge Vent

Most effective exhaust

• Type: Continuous vent along entire ridge
• NFA: 18 sq in per linear foot typical
• Coverage: Cut 2-3" slot both sides of ridge
• Pros: Even exhaust, invisible, weather-resistant
• Cons: Requires soffit intake to work
• Cost: $3-6 per linear foot

Soffit Vents (Intake)

Essential for system

• Type: Continuous soffit strip or individual vents
• Coverage: 50% of total NFA requirement
• Installation: Must have clear path to attic space
• Baffles: Install rafter baffles to keep insulation clear
• Pros: Creates airflow with ridge vent
• Cost: $1.50-3 per linear foot

Box/Turtle Vents

Static roof vents

• Type: Individual vents placed on roof
• NFA: 50-60 sq in per vent typical
• Spacing: 1 vent per 150 sq ft attic space
• Location: Upper third of roof, both slopes
• Pros: Inexpensive, works without ridge vent
• Cost: $8-25 per vent

Gable Vents

End wall ventilation

• Type: Louvered vent in gable end wall
• Size: Based on attic size calculation
• Location: High on gable end walls
• Note: Don't mix with ridge vents (short circuits)
• Pros: Good for gable roofs without ridge
• Cost: $15-60 per vent

Turbine Vents

Wind-powered exhaust

• Type: Wind-spinning turbine on roof
• NFA: Equivalent to 2-3 static vents when spinning
• Size: 12" or 14" diameter common
• Pros: Active ventilation when wind blows
• Cons: Can be noisy, visible, requires maintenance
• Cost: $25-75 per turbine

Power Attic Vent

Electric or solar fan

• Type: Thermostat-controlled fan
• CFM: Size based on attic volume
• Power: Hardwired or solar panel
• Pros: Forced ventilation, very effective
• Cons: Operating cost, can pull conditioned air
• Cost: $150-500 installed

Ventilation System Design

Best system: Ridge vent (exhaust) + continuous soffit vents (intake) for balanced airflow
Calculate NFA: Attic sq ft ÷ 150 = total NFA required in square feet
Split 50/50: Half NFA at soffit (intake), half at ridge/roof (exhaust)
Don't mix types: Using ridge + gable vents creates short-circuit (air takes easy path)
Rafter baffles: Install foam/cardboard baffles to keep soffit vent path clear of insulation
Seal attic penetrations: Light fixtures, fans, plumbing stacks to prevent air leakage

Step-by-Step Installation Process

Safety Setup & Deck Inspection

•Install roof brackets or scaffolding for safe working platform
•Set up ladder safely with stabilizer, secure at top
•Wear fall protection harness if working on steep slopes (6:12 and up)
•Inspect roof deck for damage, replace any rotten or broken sheathing
•Ensure deck is properly fastened with no loose or missing panels
•Verify deck is flat within 1/8" in 6 feet (sand high spots, shim low areas)

Install Drip Edge & Ice/Water Shield

•Install drip edge along all eaves, nail every 12" with roofing nails
•Drip edge should extend 1/4"-3/4" beyond fascia board
•Apply ice & water shield from eave up to 24" past interior warm wall
•In valleys, install 18-24" wide ice & water shield centered on valley
•Around chimneys, pipes, and vents, install ice & water shield 6" beyond
•Install drip edge along rakes (gable ends) over underlayment

Install Underlayment

•Roll out felt or synthetic underlayment starting at eave
•Overlap horizontal seams by 2-4", vertical seams by 6"
•Stagger vertical seams (don't line up in straight line)
•Fasten with plastic cap nails or staples every 12-18" and at seams
•Cut underlayment around roof penetrations, seal with ice & water shield
•Ensure underlayment is flat with no wrinkles or buckles

Install Valley Treatments

•For open valleys: install 24" wide metal valley flashing with crimped center
•For closed cut valleys: ensure full coverage with ice & water shield
•Overlap valley metal sections by 6" minimum, upper piece over lower
•Seal valley metal overlaps with roofing caulk
•Install valley from bottom (eave) to top (ridge)
•Mark chalk lines 2-3" from valley center for shingle cut lines (closed valleys)

Install Starter Strip

•Install starter strip along all eaves and rake edges
•Overhang drip edge by 1/4"-3/4" (check local code)
•Place sealant strip toward roof (facing up)
•Nail 3-4" above eave edge, above sealant strip, every 12"
•Ensure starter strip joints don't align with first course joints
•On rakes, run starter strip flush with rake drip edge

Install First Course & Establish Pattern

•Start first full shingle course, align bottom with starter strip
•For 3-tab: cut 6" off first shingle to stagger pattern
•For architectural: use full shingle at rake edge
•Nail each shingle per manufacturer specs (4-6 nails)
•Keep nails on or just above nail line (never high nail)
•Maintain 1/4"-3/4" overhang at rake edges
•Snap horizontal chalk line for each course to ensure straight rows

Continue Field Courses

•Follow shingle exposure marks (typically 5" for 3-tab, 5-5/8" architectural)
•Stagger shingle joints (offset by 6" minimum for 3-tab, random for architectural)
•Check alignment every 3-4 courses with chalk line
•In valleys, extend closed-cut shingles 12" past centerline on first plane
•Cut second plane shingles along chalk line, clip top corner at 45°
•Never nail within 6" of valley centerline
•Work both sides of valley alternately to maintain balance

Flash Roof Penetrations

•For pipe vents: use rubber pipe boot flashing, shingle below and sides
•Leave top of boot exposed, slide under shingles above vent
•For chimneys: install step flashing up sides, counter-flashing in mortar joints
•Skylights: install per manufacturer instructions with proper flashing kit
•Nail flashing to deck only, not to vertical surfaces (allows movement)
•Seal all flashing edges with roofing caulk for watertight seal

Install Ridge Cap

•If using ridge vent: cut 1-1.5" slot on each side of ridge peak
•Install ridge vent per manufacturer instructions (nail flanges to deck)
•Cut ridge cap shingles from field shingles (cut into thirds) or use pre-cut caps
•Start ridge cap at end opposite prevailing wind direction
•Install with 5" to 5-1/2" exposure, bending over peak
•Nail each cap with 2 nails, 1" from each edge, 5-1/2" from leading edge
•Final cap: seal nails with dab of roofing cement

Final Inspection & Cleanup

•Walk entire roof checking for lifted or improperly nailed shingles
•Verify all flashing is properly installed and sealed
•Check all valleys for proper cuts and no exposed nails
•Seal any exposed nail heads with dab of roofing cement
•Clean all debris from roof and gutters (nails, wrappers, shingle pieces)
•Inspect ground perimeter with magnet to pick up dropped nails
•Document installation with photos for warranty purposes
•Provide homeowner with warranty information and maintenance tips

Best Practices & Common Mistakes

DO:

Use proper fall protection when working on roofs (harness, roof brackets)
Install ice & water shield at eaves (entire overhang + 24\" inside) and valleys
Follow manufacturer nailing patterns exactly (4-6 nails per shingle)
Install starter strip at eaves and rakes for proper seal
Ensure adequate attic ventilation (1:150 ratio, intake and exhaust balanced)
Check weather forecast - install in dry, moderate temperatures (40-85°F ideal)
Snap chalk lines frequently to maintain straight, aligned courses
Store shingles on flat, stable surface and mix bundles for color consistency

DON'T:

Work on roofs without proper safety equipment (leading cause of contractor deaths)
High nail shingles (above nail line) - causes blow-offs and voids warranty
Overdrive or underdrive nails (flush with surface is correct)
Install shingles in cold weather (below 40°F) - sealant won't activate
Skip starter strips (causes wind blow-offs at eaves and rakes)
Nail through valleys (creates leak points in critical water channel)
Mix gable vents with ridge vents (creates ventilation short-circuit)
Install new shingles over multiple old layers (creates uneven surface, voids warranty)