Introduction
Under shingles the roof includes the deck, the underlayment, and the fasteners that tie it all together. These layers protect the attic from leaks and help the shingles sit evenly. This intro covers what to look for and how to check your work as you go.
The DIY path here focuses on practical steps you can follow on a basic job site. We’ll cover how to inspect for a solid deck, when and how to lay underlayment, and where to pause if you see trouble. When in doubt, check the product label, manufacturer instructions, or local rules before proceeding.
Key takeaways
- Verify roof deck is dry and structurally sound before any shingle work.
- Follow flashing, drip edge, and edge details to prevent wind-driven leaks.
- Ventilate attic and control moisture to avoid trapped humidity and rot.
- Inspect underlayment quality and nails; use manufacturer guidance for fasteners; wear PPE.
- Spot-check for gaps, proper laps, and clean edge transitions during install.
- Stop points: halt work if rain imminent, decking moisture shows, or defects.
Table of Contents
- Introduction
- Key takeaways
- Overview: Layers of a Typical Shingle Roof
- Flashing, Drip Edge, and Edge Details
- Ventilation and Roof Moisture Control
- Tools and Materials Checklist for DIY Shingle Installations
- Step-by-Step DIY Process: Prep Through Shingle Installation
- Common Problems, Diagnostics, and Stop Points for Diyers
- Material Specs, Codes, and When to Call a Professional
- Visual Checkpoints and Quality Inspection Checklist
- Conclusion
- FAQ
Overview: Layers of a Typical Shingle Roof
Shingles sit on top of a prepared deck. Beneath them lies a sequence of layers that protect the home from water and weather. Each layer has a job, from shedding rain to venting moisture from the attic.
The deck provides a solid base, followed by a underlayment, then any ventilation barriers, and finally the shingles themselves. Understanding this stack helps you spot where trouble can start. This section covers the standard order and why it matters for protection and ventilation.
Roof deck (sheathing)
The roof deck, or sheathing, is the foundation of your shingle roof. It’s usually made from plywood or OSB (oriented strand board).
Thickness matters. Common thicknesses are 7/16″ and 1/2″. Thicker isn’t always better; check local building codes to ensure you’re using the right thickness for your roof’s load.
Before laying underlayment, inspect for defects. Look out for warping, delamination (layers separating), or signs of water damage. If you find any, replace those sheets before proceeding.
Underlayment types (felt vs. synthetic)
Alright, listen up. You’ve got your roof deck all set, now it’s time to pick an underlayment. There are two main types: asphalt-saturated felt and synthetic. Let’s break ’em down.
Felt, or asphalt-saturated felt, is the old standby. It’s cheap, easy to find, and most pros use it. But here’s the thing – it can’t beat synthetics in terms of durability and longevity. Felt’s good for a quick, budget job, but if you want something that’ll last, consider synthetic.
Now, synthetic underlayments are made from plastic materials like polyethylene or polypropylene. They’re more expensive than felt, but they’ve got some serious advantages. Synthetics won’t absorb water like felt does, so they stay lighter and easier to walk on even when it’s raining. Plus, they hold up better against UV rays and wind, making them a great choice for long-term protection.
Ice and Water Shield / Self-Adhered Membrane
After laying your roof deck and underlayment, it’s time to install the ice and water shield. This isn’t your regular underlayment – it sticks to itself and the roof, creating a barrier that keeps water out.
Where to install: Run it along the eaves, up valleys, and around penetrations like vents and chimneys. Start at the lowest point of your roof and work your way up, overlapping each row by at least 6 inches.
Critical stop points: Don’t forget to wrap ice and water shield around any protrusions on your roof. Cut it to fit snugly against these areas, then seal with a metal flashing or roofing cement if needed.
Flashing, Drip Edge, and Edge Details
Flashing directs water around roof penetrations and edges. A drip edge guides water off the eave and into the gutter line. Edge details keep the outer boundary secure against wind uplift.
During a re-roof, you assess where flashing should be replaced or new pieces added. Verify manufacturer and local rules for required placements. When in doubt, check product labels and installation instructions before proceeding.
Drip edge installation
The drip edge is your roof’s first line of defense against water intrusion. Here’s how to install it right:
Eaves and Rakes: Install drip edge at both eaves (lower edges) and rakes (sides). It should overhang the fascia by about 1/2 inch.
Overlap drip edges properly. At eaves, the lower piece overlaps the upper one. At rakes, they meet in a butt joint, with no overlap needed.
Interface with underlayment: Drip edge should be installed over the underlayment. This ensures water runs off smoothly and doesn’t seep back up under shingles.
Valley and step flashing
Valleys direct water off your roof. Here’s how to flash them:
Woven vs. Open Valleys: Woven valleys use two layers of shingles, while open valleys expose the underlayment. Both work, but woven is more durable.
Step flashing around walls and chimneys prevents water intrusion at these critical points. Install step flashing with a 3-inch overlap between pieces, and tuck it behind the wall or chimney material.
Check overlaps: Ensure each piece of step flashing overlaps the one below it by at least 2 inches. This ensures no gaps where water can sneak in.
Plumbing vents, skylights, and chimney flashing
Roof penetrations need special attention to prevent leaks. Here’s how:
Flashing Types: Use step flashing for plumbing vents and skylights, and use a cricket (small raised ridge) with flashing for chimneys.
Underlayment and Flashing: Install underlayment up the sides of penetrations before installing flashing. This ensures water can’t sneak in behind the flashing.
Inspect Common Failure Points: Check boots around plumbing vents and skylights, and ensure they’re securely nailed with no gaps. For chimneys, check the cricket for proper pitch and flashing overlap.
Ventilation and Roof Moisture Control
Under-roof ventilation helps equalize attic air and reduces condensation. Ridge vents and soffit vents work together to move air through the roof cavity. Proper airflow protects insulation and minimizes moisture buildup.
Underlayment and vents combine to block wind-driven rain while allowing moisture to escape. Inspect the balance between intake and exhaust paths during a re-roof project. If you’re unsure, consult the underlayment instructions and local code guidance.
Baffle installation in soffits/attic
Under-roof ventilation is crucial to keep your home dry and comfortable. Baffles help maintain a clear path for air to flow from the eaves to the ridge, preventing hot, moist air from getting trapped.
Install baffles at the eave edge, spacing them 16″ on center. They should extend up to the insulation line, keeping the airflow channel open. Use a tape measure and level to ensure straight installation.
Without baffles, you might face issues like moisture buildup, mold growth, or even ice dams in winter. If your attic lacks baffles, install them before shingling. It’s easier and cheaper than fixing problems later.
Attic vapor barriers vs. roof underlayment
Understanding the difference between attic vapor retarders and roof underlayment is key to controlling moisture in your home.
Roof underlayment, like felt or synthetic materials, goes underneath the shingles. It protects against water intrusion but doesn’t control moisture from within the house.
Attic vapor retarders, on the other hand, go above the insulation and prevent moisture from the living space below from migrating into the attic. They’re typically installed during new construction or major renovations.
Before shingling, if you notice moisture issues in your attic, like condensation on rafters or joists, address them first. Install a vapor barrier if needed, then proceed with underlayment and shingles.
Tools and Materials Checklist for DIY Shingle Installations
Gather a focused set of hand and power tools for the job. Include fasteners appropriate for the roof and underlayment, plus flashing components. Add safety gear and a sturdy ladder or access system for safe work.
Choose underlayment types and flashing pieces based on the roof profile and local conditions. Keep a list of required components and verify specs on labels or manufacturer sheets. When in doubt, confirm with product guides and local requirements.
Fasteners, adhesives, and compatibility
Before you start your DIY shingle installation, use this checklist to ensure you have the right fasteners, adhesives, and that they’re compatible with each other. This will save you time and prevent costly mistakes.
- Nails: Check length (usually 1-1/4″ to 2″) and type (clipped head or smooth shank). Confirm they match your shingle’s manufacturer recommendations.
- Hurricane straps: If required by local codes, ensure they’re compatible with your roofing system. Check their length and strength rating.
- Roofing cement or sealant: Verify it’s designed for roofing applications. Check the label to confirm it’s suitable for your shingle type (e.g., asphalt, wood, metal).
- Drip edge flashing: Ensure it matches your roof’s overhang and is compatible with your chosen underlayment.
- Underlayment: Check it’s rated for your climate (e.g., 30# or 60# felt, synthetic, or rubberized). Confirm it’s compatible with your shingle type.
- Starter strips: Ensure they match your chosen shingle and are cut to the correct length. Check they’re designed for your specific roof pitch.
- Ventilation materials: Confirm they’re suitable for your roof’s size, pitch, and local ventilation requirements (e.g., ridge vents, soffit vents).
- Ice and water shield: If required, check it’s compatible with your underlayment and shingles. Ensure it covers the necessary areas (eaves, rakes, valleys).
Quick rule: Always follow manufacturer guidelines for fasteners, adhesives, and compatibility to avoid costly rework and ensure a durable roof.
Safety gear and roof access equipment
Before you start any work on your roof, ensure you have the right safety gear and equipment. Use this checklist to double-check everything before you begin.
- Hard Hat – Protects against falling debris. Make sure it fits snugly but comfortably.
- Safety Glasses – Shields eyes from dust, debris, and nails. Ensure they meet ANSI Z87.1 standards.
- Hearing Protection – Protects against loud noises like nail guns or hammers. Use earplugs or earmuffs that provide at least 20 dB reduction in noise levels.
- Work Gloves – Provides grip and protection for hands. Check they’re not too thick to handle tools safely.
- Safety Harness – Essential for roofs with a pitch of 6/12 or greater. Ensure it’s rated for your weight and the roof’s slope, and follow manufacturer instructions for setup.
- Ladder – Stable and tall enough to reach the roof safely. Check for sturdiness before climbing, and secure it at the top with a ladder stabilizer or hooks.
- Roof Jacks – Provide stable working platforms on sloped roofs. Ensure they’re rated for your weight and the roof’s load capacity, and follow manufacturer instructions for setup.
- Rubber-Soled Shoes – Offers better grip on slippery surfaces. Check soles are in good condition with no worn-out areas.
Quick rule: Always work with a buddy when on the roof, and ensure one person is secured with a safety harness at all times to prevent falls.
Step-by-Step DIY Process: Prep Through Shingle Installation
Start with a thorough inspection of the deck and repair any loose or damaged areas. Clean the surface and lay down the chosen underlayment in proper orientation. Plan the nailing pattern and starter course before installing shingles.
Install flashing and edge components as you progress, then complete the shingle rows with correct fastener placement. Finish with a clean-up pass and a final inspection for gaps and lift points. If unsure about a step, verify instructions and stop points before moving forward.
Step-by-Step Installation Process
The following is a clear, numbered sequence of practical steps for your DIY roofing project from preparation to final installation and cleanup.
- Preparation: Inspect the roof deck, gather tools and materials, and ensure safety gear is ready. Why: To identify issues early and prevent accidents.
- Remove old shingles: Strip off existing shingles, nails, and felt paper. Why: To expose the roof deck for inspection and preparation.
- Inspect and prepare the roof deck: Follow the checklist in the next section to ensure a flat, sound surface. Why: A solid base ensures proper underlayment adhesion and shingle installation.
- Install underlayment and ice/water shield: Follow the guidance in the subsequent sections for precise placement and overlapping. Why: To protect your roof from moisture and leaks.
- Install drip edge, flashing, and other details: Ensure all edges are protected to prevent water intrusion. Why: Drip edge and flashing safeguard your roof’s perimeter.
- Lay out shingles: Start at the bottom left corner, using starter strips and alignment lines. Why: Proper layout ensures a neat, straight installation.
- Install shingles: Nail according to the manufacturer’s pattern, working from the bottom up. Why: Correct nailing secures shingles and prevents wind damage.
- Inspect and clean up: Check your work for any missed nails or damaged shingles before declaring the job done. Why: A final check ensures a quality job and prevents callbacks.
Inspection and deck preparation
Before installing underlayment, use this checklist to identify and repair any issues with your roof deck.
- Check for rotten sheathing: Inspect the entire deck for soft spots or signs of decay. Why: Rotten sheathing can lead to leaks and structural problems.
- Replace damaged nails: Remove any popped or rusted nails and replace them with new ones. Why: Damaged nails can cause shingles to lift and allow water intrusion.
- Ensure a flat surface: Check for warping, sagging, or other irregularities. Why: A flat deck ensures proper underlayment adhesion and shingle installation.
- Inspect rafters: Look for signs of rot, cracks, or other damage. Why: Damaged rafters can compromise the entire roof structure.
- Check for proper spacing: Ensure rafters are evenly spaced and aligned. Why: Incorrect spacing can lead to structural issues and improper shingle installation.
- Inspect ventilation: Check that soffit vents, ridge vents, and other ventilation components are intact and unobstructed. Why: Proper ventilation prevents moisture buildup and extends the life of your roof.
- Check for proper attic insulation: Ensure there’s adequate insulation to protect your roof from ice dams. Why: Insufficient insulation can cause ice dams, leading to leaks and damage.
- Inspect chimney flashing: Check that the flashing around your chimney is secure and in good condition. Why: Damaged flashing can allow water intrusion around the chimney.
- Check for proper roof pitch: Ensure your roof has a sufficient slope to shed water effectively. Why: A flat or low-pitched roof can lead to water pooling and leaks.
Quick rule: If you find extensive damage, consider calling a professional roofer for advice before proceeding.
Installing underlayment and ice/water shield
Underlayment and ice/water shield protect your roof from moisture. Here’s how to install them correctly.
Underlayment: Start at the bottom edge of the roof, unrolling the underlayment in horizontal strips that overlap by at least 2 inches. Secure it with staples or nails every 6 inches along the overlap and every 12 inches elsewhere. Ensure each strip is aligned with the one below it.
Ice/water shield: Install this self-adhered membrane in a similar manner, but start at the bottom edge of the roof eaves and work up. Overlap each strip by at least 4 inches and press down firmly to ensure a good seal. Be sure to install it under any valleys or other areas prone to ice dams.
After installing both layers, step back and inspect your work. Ensure there are no gaps, wrinkles, or other issues that could allow water intrusion. Double-check the overlaps to make sure they’re secure.
Shingle layout and installation
Proper shingle layout and installation ensure a durable, attractive roof. Here’s how to do it right.
Starter strips: Begin at the bottom left corner of your roof, using starter strips to create a straight edge. Align the tabs with the drip edge and secure them with nails according to the manufacturer’s pattern.
Alignment lines: Snap chalk lines on the roof to guide shingle placement. Start at the bottom and work your way up, ensuring each course is aligned with the one below it.
Nailing patterns: Follow the manufacturer’s nailing instructions precisely. Typically, this involves nailing through the tabs into the decking, spacing nails evenly along the shingle.
Ridge caps: Once you’ve reached the ridge, install ridge cap shingles to cover the exposed nail heads and provide a finished look. Ensure they’re properly aligned and secured with nails.
Final inspection: After installing all shingles, walk your roof to inspect your work. Check for any missed nail heads, damaged shingles, or other issues that need attention before declaring the job done.
Common Problems, Diagnostics, and Stop Points for Diyers
Blow-off or lifted shingles often signal fastener or underlayment issues. Look for loose edges and verify proper nailing. Inspect around penetrations where leaks commonly start.
Ice dam damage and condensation leaks are typical red flags. Check for adequate attic ventilation and proper insulation at the eave line. At each stage, use a checklist to confirm critical steps were completed correctly.
Leak Detection and Repair Workflow
Start leak diagnosis in the attic. Look for water stains, mold, or damp insulation.
Trace leaks back to the roof. Mark each spot with a chalk line from below.
Temporary fix: Apply roofing tar over the leak, press on a piece of roofing felt, and secure it with nails. But stop here. Don’t assume the problem’s solved until you’ve found and fixed the root cause.
Permanent repair involves finding the exact shingle or flashing causing the leak, replacing it, and ensuring proper sealing. If you’re unsure, reassess your diagnosis before proceeding.
Wind Damage and Uplift Prevention
Proper nailing is key to wind resistance. Use 12-16 penny nails, spaced every 5 inches along the seam.
Underlayment matters too. Synthetic or felt underlayment should be secured with cap nails at each seam and at the edges.
Edge details are crucial. Use drip edge flashing at the eaves to prevent wind-driven rain from getting underneath. At the rakes, use rake edge flashing to keep wind from lifting shingles.
If you notice any significant wind damage, stop and consult a professional roofer before proceeding with repairs.
Material Specs, Codes, and When to Call a Professional
Know the fire rating class options and how they apply to your climate. Review underlayment temperature limits and compatibility with shingles. Check any code references that pertain to your area.
Offer safe ranges when specifics vary and confirm with manufacturer instructions. If standards differ locally, contact a licensed pro for guidance and a code-compliant path. Always verify with current label information and local rules.
Shingle and Underlayment Ratings to Check
Before you start, check these key ratings on your shingles and underlayment. They ensure your roof can handle your climate and meet building codes.
Shingles:
Check the class – it’s usually A, B, or C. Class A is best, offering excellent fire resistance. Also, look at the warranty terms. 20-30 years is common for fiberglass shingles.
Underlayment:
Check its temperature limits. It should handle your coldest winter temps. Also, note if it’s rated for ice/water shield use – you’ll need this around eaves and rakes.
Situations Requiring a Licensed Roofer
Safety first, DIYer. Here are when you should call in the pros:
Structural damage:
If your decking is damaged – rotted, warped, or missing – it’s time to bring in a pro. They can assess and fix structural issues safely.
Complex flashing:
Around chimneys, skylights, or vents, flashing keeps water out. If you’re unsure how to install it, call a roofer. It’s a common source of leaks if not done right.
Steep/high roofs:
If your roof is steep or high, it’s dangerous to work on. Pros have the gear and training for these jobs.
Code enforcement:
Some areas require permits for roof work. If you’re unsure, check with local building codes. It’s better to know before starting.
Visual Checkpoints and Quality Inspection Checklist
Use a room-to-roof mindset to verify both indoor and roof-side aspects. Scan for consistent alignment, clean edge lines, and properly seated shingles. Feel edges for secure seating and uniform gaps.
Mark pass/fail points for each milestone, such as underlayment reach and flashing fit. At the end, perform a final overall inspection and address any discrepancies. When in doubt, rely on the manufacturer guidance and your local rules for inspection criteria.
Pre-shingle sign-off points
Before you start shingling your roof, use this checklist to ensure everything is ready. This will help prevent costly mistakes and rework.
- Deck flatness: Check that the roof deck is flat and even. Use a level or straight edge to confirm. Any significant bumps or dips could cause shingles to lay improperly, leading to leaks or premature failure.
- Underlayment seams: Ensure all underlayment (felt paper) seams are properly overlapped and secured with staples or nails. Check for any gaps or tears that could allow water intrusion.
- Drip edge installed: Verify that drip edge flashing is installed along the eaves and rakes. This prevents water from getting behind the shingles and causing rot.
- Flashing at valleys: Check that valley flashing is in place to protect against water penetration where two roof planes meet.
- Chimney flashing: Ensure chimney flashing is properly installed to prevent water from entering around the chimney. Look for any gaps or cracks.
- Ventilation checked: Confirm that all vents and exhaust fans are functioning correctly. Proper ventilation prevents moisture buildup, which can damage shingles and roof structure.
- Nailer boards in place: Make sure nailer boards (2x4s) are securely fastened to the rakes and eaves. These provide a secure nailing surface for the first course of shingles.
- Roof clean: Ensure the roof is free of debris, such as leaves or twigs. This allows for proper adhesion of the underlayment and shingles.
Quick rule: Always check local building codes before starting any work to ensure you’re in compliance with your area’s specific requirements.
Final inspection and maintenance tips
Once your roofing project is complete, it’s crucial to conduct a final inspection to ensure everything was installed correctly. Use this checklist to verify the quality of work and maintain your roof’s longevity.
- Check for Nails/Parts: Ensure no nails or small parts are left behind that could cause damage or injury.
- Inspect Shingles: Check each shingle for proper installation, ensuring they’re secure and aligned. Look for any broken, missing, or damaged ones.
- Verify Flashing: Inspect all flashing around vents, chimneys, and skylights to ensure it’s properly installed and sealed to prevent leaks.
- Gutter Check: Make sure gutters are securely attached, free of debris, and directing water away from the foundation. (See “Pre-shingle sign-off points” for more on gutter checks.)
- Roof Valleys: Ensure valleys are properly shingled to direct water off the roof efficiently.
- Drip Edge: Confirm drip edge is installed at the edges of your roof to prevent water from getting under the shingles and causing damage.
- Debris Cleanup: Remove all debris, tools, and materials from the jobsite to maintain a safe environment. (See “Pre-shingle sign-off points” for more on jobsite cleanup.)
- Routine Maintenance Intervals: Schedule regular inspections (every 3-5 years) to check for any signs of wear, damage, or potential issues.
Quick rule: Always prioritize safety when inspecting your roof. Use secure ladders and only walk on designated areas to avoid damaging the shingles.
Conclusion
Focus on safe, durable work that protects the roof and your home. Nail quality edge details, flashing, and ventilation first, then finish the shingles with steady, repeatable steps. A solid finish today saves leaks and costly repairs tomorrow.
Check in this order as you move: inspect edges and drip areas for clean paint lines and proper flashing, verify ventilation and moisture control are in place, confirm you have the right tools and materials, follow the prep through installation steps, and perform the final visual and quality checks before you call it done. Stay systematic, test small areas, and keep the work surface stable and dry at all times; if any part of the task feels rushed or unsafe, pause and reassess before continuing.
Common mistakes to avoid include skimping on flashing or drip edge, skipping safety anchors or fall protection, and rushing through diagnostics or inspections. Always practice safe work habits: wear proper footwear and eye protection, use a stable ladder and a second person for control, and never work on wet or icy surfaces. If you’re unsure about code requirements, material specs, or flashing details that could lead to leaks, pause and verify against the guidance in the referenced sections or consult a pro.
If signs point to hidden damage, complex flashing, or roof sections beyond your experience, call a professional rather than pushing on. The job is done right when you can stand back, view a tight, clean edge, and be confident the roof will shed water for many seasons. Stay steady, you’ve got this.
FAQ
What goes directly under the shingles on a typical roof?
Under the shingles you’ll usually find a roof deck or sheathing, plus an underlayment. The underlayment is meant to shed water and provide a second line of defense if the deck leaks. Check the manufacturer instructions for the exact order and type they want.
How should underlayment be installed with flashing and edge details?
Lay the underlayment over the deck with the edges turned up at the eaves and rake lines as required. Install flashing and drip edge over the underlayment where appropriate to direct water away from the fascia. Follow product labels for laps, overlaps, and fastener locations.
What are the critical signs that something is wrong under the shingles?
Look for sticking or buckling underlayment, water stains on the deck, or damp spots inside the attic. If flashing or edge details aren’t integrated with the underlayment, you’ll get leaks sooner or later. Always inspect after completion for gaps or loose areas.
What should I verify before I finish the roof?
Double-check that the underlayment covers all sheathing surfaces and overlaps correctly. Confirm you have proper ventilation around the eaves and ridge to prevent moisture buildup. If in doubt, read the product label and manufacturer instructions for your specific underlayment and roof setup.