How to Replace Asphalt Shingles

Replacing worn or damaged asphalt shingles on your roof can seem like an intimidating task, but with the right materials, tools, and safety precautions, a DIY roofing project is very achievable for a homeowner. Asphalt shingles are one of the most common and affordable roofing materials, but over time, exposure to weather, sunlight, foot traffic, and other factors can cause them to wear out. Tackling a roof replacement job yourself rather than hiring a professional roofer can save thousands of dollars in labor costs. Follow this comprehensive guide to learn everything you need to know about how to replace asphalt shingles on your roof.

Assessing the Condition of Your Roof

Before diving into a roof replacement project, the first step is to thoroughly examine the current condition of your asphalt shingle roof to determine if replacement is truly necessary or if minor repairs may suffice. Here are some signs that it may be time for a full roof replacement:

Severe curling or buckling of shingles: Normal wear may cause some slight curling of shingle edges, but major buckling, curling, or warping can indicate heat damage or moisture issues.
Missing or torn shingles: A few missing shingles here and there can be repaired, but if you have multiple areas of missing, torn, or otherwise damaged shingles, replacement is likely needed.
Deterioration of roofing materials: Look for cracks, splits, breaks, and excessive granule loss in the shingles, as well as signs of rot or deterioration in the roof deck and flashing.
Leaks: Persistent water spots or stains on your ceiling can reveal leaks from damaged shingles. Even a single leak indicates the whole roof needs replacement.
Age: Asphalt shingles typically last 15-30 years before replacement is needed. If your roof is near or past that age range, its time is probably up.
Number of existing layers: Roofs should have no more than two layers of shingles. If removal reveals more than this, replacement is required.

Carefully inspecting for these issues on your roof helps determine if replacement should be pursued. If only minor repairs seem necessary, the job may not require a full roof tear-off.

How to Measure Your Roof

Once you’ve decided to move forward with replacing your asphalt shingle roof, the next essential step is accurately measuring the total square footage of your roof to determine how much new material you will need to purchase. Here’s how to measure a roof:

Materials Needed

Measuring tape
Ladder
Paper and pencil
Quick access to calculator on mobile phone

Steps to Measure

Use the ladder to safely access the roof area. Bring your measuring tape, paper, and pencil.
Starting at one corner, measure across the full width of the roof section, from edge to edge in feet.
Next, measure the length of that roof section from top to bottom in feet.
Multiply the width x length to get the square footage of that individual section.
Repeat steps 2-4 to measure each adjoining roof section, keeping notes of all measurements.
Use a calculator to tally up the total square footage of the entire roof.
Divide this total square footage by 100 to determine how many “squares” are on the roof (one square = 100 square feet of roof area).

Accurately measuring and calculating the square footage of the roof area is essential to buying enough new shingles and materials for the replacement project. Having this measurement information on hand will also be useful when placing orders at your local home improvement store.

How to Estimate Shingle Quantities Needed

Once the total square footage of the roof area is determined, you can estimate how much new shingle material needs to be purchased. The amount can vary slightly depending on the type of shingle selected, but here is a basic guide:

For a standard three-tab asphalt shingle, order 1 square (100 sq ft) of shingles per roof square.
For a thicker architectural or laminated shingle, order 1.5 squares per roof square.
Add 10% extra as overage to have spare shingles for repairs.

So for example, if your roof is 20 squares, and you plan to use architectural shingles, you would need:

20 squares x 1.5 squares per roof square = 30 squares
Add 10% overage = 3 extra squares
Total shingle squares needed = 33

Use this formula to estimate your order. Gathering a slightly greater quantity prevents running out of shingles mid-project.

How to Choose the Best Shingle Type

Many types of asphalt shingle materials are available when replacing a roof. The three main categories are:

Three-Tab Asphalt Shingles

Most affordable option
Layered construction with staggered tabs
Life expectancy 15-20 years

Architectural Shingles

Also called laminated or dimensional shingles
Multilayer construction creates texture
Life expectancy 25-30 years

Luxury Shingles

Specialty shingles with unique designs
Max durability and weather resistance
Life expectancy 35-50 years

Consider factors like budget, durability needs, and aesthetics. A professional roofer can provide recommendations on the best shingle type for your particular roof. High quality materials like architectural shingles provide excellent protection and can increase resale value.

How to Choose Other Roofing Materials

In addition to the asphalt shingle squares, extra roofing materials needed for the job include:

Underlayment: Synthetic underlayment or roofing felt creates a protective barrier.

Drip edge: Lined metal flashing installed along roof edges.

Ridge vent: Ventilation system installed along the roof ridge.

Flashing: Lined metal flashing protects joints and valleys.

Roofing nails: 1-1/2″ to 2″ corrosion-resistant nails.

Vent caps: Cover and protect plumbing vent pipes.

Consult a materials list and ensure you have the recommended quantities of each item. A roofer can help you determine the exact product specifications required.

How to Find a Reliable Roofing Contractor

While a determined DIYer can replace their own roof, many homeowners opt to hire a professional roofing contractor for big jobs like full roof replacements. Their expertise can ensure proper installation and protect against any serious issues down the line. Here are some tips for finding a qualified, reliable roofing company:

Ask for recommendations from neighbors and friends who had their roofs replaced.
Verify licensing, insurance, and bonding. This protects you from liability issues.
Look for companies that have been in business for several years or more. This indicates stability.
Check ratings and reviews on sites like Google, Yelp, and the Better Business Bureau. Look for consistent positive feedback.
Get 3-4 detailed quotes to compare scope, prices, and material types.
Ask about warranties. Many shingles have 20-50 year warranties.

Taking time to vet potential roofers helps ensure you choose one with the proper experience, qualifications, and track record for the job.

How to Prepare for a Roof Replacement Project

With a reliable contractor secured or if doing it yourself, proper preparation is key to any successful roofing project. Here are important steps to take before starting tear-off:

Inform your insurance company of the upcoming roof replacement for proper coverage.
Clear roof area of debris, plants/trees, furniture, etc that could get in the way.
Install roofing felt underlayment and drip edge flashing around roof perimeter.
Cover exterior doors, windows, landscaping, etc to protect from falling debris.
Rope off areas around the home to restrict access and prevent injury from falling objects.
Shut off power to roof-mounted features like attic fans, vents, powered antennas, etc.
Arrange for dumpster rental for disposal of old roofing materials.

Taking these preliminary precautions makes the work much smoother and safer once shingle removal commences.

How to Replace Asphalt Shingles Step-by-Step

Once proper planning, prep work, and safety precautions are in place, you’re ready to get started with the roof shingle replacement process itself. This is a general step-by-step overview of how to replace asphalt shingles on an existing roof:

Step 1: Tear Off the Old Shingles

Remove existing shingles in sections, starting at the top and working down.
Use a roofing shovel, pry bar, or other tools to carefully pry up and tear off the old shingles.
Remove all nails and sweep the roof deck thoroughly.
Dispose of all debris safely in a dumpster.

Step 2: Inspect and Repair the Roof Deck

With old shingles removed, carefully inspect the plywood or OSB roof deck underneath.
Look for signs of rot, deterioration, or structural damage and repair as needed.
Replace any damaged roof deck sections.

Step 3: Install New Drip Edge Flashing

Apply new metal drip edge flashing along eaves and rake edges.
Secure with roofing nails. Flashing protects edges from water infiltration.

Step 4: Install Underlayment

Cover roof deck with new synthetic underlayment for an added weather barrier.
Follow manufacturer instructions for proper installation.

Step 5: Install Starter Shingles

Cut shingles into thin starter strips and install along lower roof edges.
This gives the first course of shingles something to seal against.

Step 6: Install New Shingles in Courses

Start at the bottom edge and work up, installing new shingles in horizontal courses.
Maintain proper exposure by aligning with tabs on underlying courses.
Nail each shingle securely, following nailing guidelines.

Step 7: Install Ridge and Hip Caps

Once field shingles are installed, apply ridge and hip caps along ridge lines and roof hips.
This covers vulnerable areas and provides a finished edge.

Step 8: Install Flashing and Venting

Place metal flashing around joints, valleys, vents and chimneys to prevent leaks.
Install attic ventilation systems like ridge and soffit vents.

Step 9: Seal and Weatherproof

Caulk around flashing, vents, and other penetrations.
Seal any exposed roofing nails with asphalt roofing cement.

Step 10: Clean Up and Dispose of Debris

Once the new shingle installation is complete, sweep and remove all roofing debris.
Properly dispose of old roofing materials in a dumpster.
Return backyard or off-limits areas around the house to normal use.

And that concludes the major steps for how to replace old asphalt shingles with a brand new roof! Take proper safety precautions, work carefully, and inspect finished work to ensure there are no leaks before enjoying your refreshed roof.

How to Install Step Flashing on a Roof

One key task that comes up during roof shingle replacement is installing new step flashing. Step flashing is small, L-shaped flashing that fits around chimneys, dormers, walls and other roof-to-wall intersections. Follow these instructions for properly installing step flashing:

Materials Needed

4-5″ wide sheet metal flashing
Tin snips for cutting flashing
Roofing nails
Asphalt roofing cement

Installation Steps

Cut flashing into 4-5 inch wide L-shaped pieces.
Apply asphalt cement to back of first flashing piece. Press firmly to vertical wall.
Nail top corner to roof deck, while bottom piece lays over shingles.
Apply next flashing pieces similarly, overlapping previous pieces by 2 inches.
Press overlapping sections firmly into cement for waterproof seal.
Cover flashing with shingles, leaving exposed vertical sections.

Properly installing new step flashing ensures water is directed over the flashing and shingles, preventing leaks at critical joints.

How to Install Ridge Vents when Replacing a Roof

Proper attic ventilation is important when replacing a roof. Ridge vents run the length of the roof peak, allowing hot air to escape. Follow these key steps to install a new continuous ridge vent:

Steps for Installing Ridge Vents:

Snap chalk lines 36 inches from peak to mark vent area.
Use a circular saw to cut a slit along each line. This creates the ventilation space.
Install ridge vent material over slit, nailing ends in place.
Cover vent with matching colored shingle caps.
Seal ends with galvanized metal flashing.

Proper ridge vent installation improves airflow while allowing the roof to maintain a finished look. It’s a crucial ventilation task when undertaking a complete shingle tear-off and replacement.

How to Replace Roof Valley Flashing

Valleys are the angles where two sloping roof planes meet. This joint is prone to leaks, making proper valley flashing essential when replacing roof shingles. Follow these steps:

Valley Flashing Installation:

Lay ice and water shield membrane along full valley length.
Install sheet metal valley flashing centered over join. Nail securely.
Apply new shingles over flashing. Trim to fit around angle.
Seal shingle edges to flashing with asphalt roof cement.
When two valley pieces join, overlap by 8 inches and seal.

Keeping roof valleys properly sealed and flashed helps channel water safely down and over eaves instead of allowing leaks. This roofing best practice should be followed each time shingles are replaced.

How to Replace Hip and Ridge Caps

The hip is where two sloped roof planes meet to form an external angle, while the ridge is the peak where planes join internally. Capping the ridges and hips provides a finishing touch when replacing asphalt shingles. Follow these tips:

Use a chalk line to ensurecaps will install straight.
Cut cap shingles to fit using aviation snips. Seal with roofing cement.
For the ridge, bend caps over peak. For the hip, bend shingles along angle.
Expose caps 6 inches to weather. Align with exposure of field shingles.
Anchor securely with roofing nails, 1 inch from edges. Nail on each side.

Proper installation of new ridge caps and hip caps returns your roof lines to a clean, finished look after a shingle tear off.

How to Dispose of Old Asphalt Shingles

Safely disposing of the existing asphalt shingles is an important step when replacing a roof. Here are some disposal tips:

Rent a dumpster to collect old shingles as you tear off sections.
Wear PPE to avoid breathing in asbestos or other hazardous particles.
Bag shingles to prevent pieces from blowing away before hauling to dumpster.
Schedule frequent dumpster emptying to prevent overflowing with roofing debris.
Contact local waste authority about disposal regulations and recycling centers that may accept shingles.
Do not burn or illegally dump old asphalt shingle materials.

Proper shingle removal and disposal techniques keep the project site clean while following environmental regulations for waste disposal.

How to Stay Safe When Replacing an Asphalt Roof

Worker safety should be the top priority on any roofing project. Follow these tips to prevent hazards when replacing asphalt shingles:

Use fall protection like harnesses and guardrails when working at heights.
Wear slip-resistant footwear to avoid falls, especially when working on steep roofs.
Use heavy gloves when handling sharp-edged shingles, flashing, metal vents, etc.
Wear eye protection, long sleeves, and dust masks to prevent debris-related injuries.
Use extra caution when working near power lines or roof-mounted features.
Hydrate and take breaks to avoid overexertion in heat.
Set up barricades and caution signs to restrict access below work areas.
Work slowly and focus on each step – do not rush.

Prioritizing safety reduces the risks inherent in roofing work. Stay alert and use all recommended precautions.

How to Inspect and Troubleshoot Common Roof Leaks

Even a newly installed asphalt shingle roof may develop minor leaks. Here is how to inspect, identify, and address some common roof leak causes:

Inspect shingle condition: Look for cracks, damage, or deterioration that allows water intrusion. Replace individual damaged shingles as needed.

Check flashing: Ensure metal step, valley, chimney and other flashings are intact and sealed down. Reseal any lifted edges with roofing cement.

Examine roof penetrations: Seal any exposed nails, vents, skylights or other roof penetrations that could allow moisture entry. recaulk as needed.

Clear debris: Remove leaves, branches and other accumulated debris that prevents proper drainage.

Unclog gutters: Clear out blockages and obstructions so water can drain off the roof properly.

Resecure loose elements: Refasten and reseal any loose shingles, vents, chimney crickets or other items that have come loose and broken seals.

Addressing leaks quickly prevents minor issues from becoming major roof damages. Inspect and troubleshoot problem areas as soon as leaks appear.

How to Maintain an Asphalt Shingle Roof

With proper maintenance and care, an asphalt shingle roof can last upwards of 30 years. Here are some tips for maximizing the lifespan of your roof:

Conduct visual