Re Tarring a Roof: A Practical Guide to Restoring Weatherproofing and Longevity

A roof tar job can extend the life of aging asphalt roofs by restoring waterproofing and sealing minor cracks. This guide explains when to re-tar a roof, the materials and tools needed, safety practices, and a clear, step-by-step process. It also covers cost considerations, maintenance tips, and when to hire a professional. By understanding the signs of wear and the correct tar application methods, homeowners can protect their homes from leaks and energy loss while ensuring durability for years to come.

Assessing The Roof Condition And Timing

Before starting a re-tar project, evaluate the roof’s overall condition. Check for curling shingles, significant granule loss, extensive cracking, and active leaks. Tar is typically used on flat or low-slope roofs where water tends to pool. If structural damage or widespread deterioration is present, professional repairs or a full roof replacement may be more cost-effective than re-tarring. Ideal timing favors dry, mild weather to allow tar to cure properly and prevent wash-off by rain.

Materials And Tools For Re-Tarring A Roof

Choosing the right materials affects durability and performance. Common components include:

• Roof tar (asphalt-based or coal-tar bitumen, depending on climate and local codes)
• Primers or bonding agents for improved adhesion
• Liquid sealant or elastomeric coating for edge seams
• Roof membrane or fabric for bridging larger cracks (optional)
• Roofing gloves, brushes, and squeegees for even application
• Putty knife and trowel for smoothing
• Ladders, harness, and fall protection to meet safety requirements
• Crack filler or compatible filler for small gaps

Consult local building codes regarding tar type and ventilation. Environmentally responsible disposal of old tar and runoff should be planned.

Safety Considerations And Preparation

Tar work involves hot materials and chemical exposures. Prioritize safety:

• Wear heat-resistant gloves, long sleeves, and eye protection.
• Ensure proper ventilation if working near enclosed spaces or on elevated roofs.
• Secure ladders and use fall-arrest systems as needed.
• Keep a clean work area to prevent slips on tar spills.
• Test tar temperature and viscosity to avoid burns or improper curing.

Prepare the roof by removing debris, cleaning surface grime, and repairing any small cracks or punctures with compatible filler before applying tar.

Step-By-Step Process To Re-Tar A Roof

Prepare The Surface

Clear dirt, moss, and loose granules. Rinse thoroughly and let the surface dry. Trim exposed flashing and edges if needed to ensure a smooth application path for tar.

Prime And Seal Joints

Apply a bonding primer to porous sections to improve tar adhesion. Inspect and seal seams, edges, and any penetrations with a compatible sealant or bridging material to prevent leaks.

Apply The Tar

Heat-tar if using hot tar methods, following manufacturer guidelines for temperature and application thickness. For cold-applied tar, use a heavy nap roller or stiff brush to build an even coat. Focus on flat sections and carefully feather edges to minimize ridges that could trap water.

Address Cracks And Patches

Fill hairline cracks with tar or crack filler. For larger cracks, apply membrane or fabric overlays and seal with tar to reinforce the area. Ensure all patches are fully sealed and smooth to avoid water pooling.

Finish With A Protective Layer

Optionally, apply an elastomeric coating or sealant to the surface for extended protection and UV resistance. This layer enhances waterproofing and reduces the frequency of maintenance.

Clean Up And Cure

Wipe excess tar from flashing and edges with a solvent recommended by the tar manufacturer. Allow the surface to cure per product instructions, typically 24 to 72 hours in dry conditions before exposure to rain or foot traffic.

Maintenance, Longevity, And Weather Performance

Proper maintenance extends the life of a re-tarred roof. Schedule periodic inspections after heavy rain, snow, or temperature swings. Look for softened patches, peel-back at edges, or new hairline cracks. Clean the surface to prevent moss or fungal growth that can degrade tar and reduce effectiveness. Re-tarring may be needed every 5 to 10 years depending on climate, roof slope, traffic, and existing substrate.

Common Issues And Troubleshooting

• Poor adhesion stems from dirty surfaces or improper priming. Re-clean and re-prime affected areas before re-application.
• Cracking after application may indicate premature curing due to heat or rain exposure. Allow proper curing time and consider a protective topcoat.
• Uneven surfaces can trap water. Re-smooth and recoat thin or inconsistent areas to ensure uniform waterproofing.
• Edge lifting often occurs at flashing or joints. Re-seal with compatible sealant or reinforce with fabric overlays.

Cost, Time, And Labor Considerations

Costs vary by roof size, tar type, and local labor rates. A typical flat or low-slope roof re-tar project may cost several hundred to a few thousand dollars, including materials and labor. DIY projects save labor costs but require proper safety equipment and time. Weather windows influence scheduling; plan for dry periods of several days to allow complete curing. Compare quotes and verify contractor credentials if hiring a pro.

DIY Versus Hiring A Professional

DIY is feasible for small, simple jobs on flat sections with minimal damage. For deteriorated substrates, multiple cracks, or complex flashings, hiring a licensed roofer is advisable. Professionals bring experience with tar types, proper heating or application techniques, and code-compliant safety practices. Verify warranties and ensure compliance with local environmental rules for tar disposal and runoff.

Environmental And Regulatory Considerations

Tar products can release volatile compounds and require careful handling. Use tar in well-ventilated areas and follow disposal regulations for hazardous materials. Respect local environmental guidelines for runoff containment and prevent tar from entering storm drains. Some municipalities have restrictions on coal-tar products; verify local codes before starting work.

Quick Tips For Successful Re-Tarring

• Choose the correct tar type and adhere to manufacturer instructions.
• Prepare the surface thoroughly to maximize adhesion.
• Schedule work in dry, moderate weather to ensure proper curing.
• Maintain a clean work area and use fall protection on elevated roofs.
• Document the project with photos for future reference and maintenance.

Frequently Asked Questions

1. How long does re-tarring a roof last? Typically 5–10 years, depending on climate and maintenance.
2. Can tar be applied over old tar? In many cases yes, but inspect for adhesion and remove deteriorated layers if needed.
3. Is re-tarring suitable for metal roofs? Tar is uncommon for metal roofs; consult a roofing professional for alternatives.