Can You Put Roll Roofing Over Shingles

Can You Put Roll Roofing Over Shingles? What Homeowners Need to Know

Whether renovating an aging roof or addressing leaks, homeowners often look for cost-effective solutions. One common question is, can roll roofing be installed over existing shingles? This article explores the feasibility, advantages, drawbacks, and best practices for putting roll roofing over shingles. It aims to help property owners make informed decisions about roofing repairs and replacements while optimizing for Bing search queries related to roofing options.

Understanding Roll Roofing and Its Characteristics

Roll roofing is an asphalt-based material sold in rolls typically 3 feet wide and 33 feet long. It is designed for straightforward application, often used on low-slope residential roofs, sheds, garages, or as a temporary fix. Its layered construction includes an asphalt-saturated felt base with mineral granules on the surface for UV protection. Compared to traditional shingles, roll roofing offers faster installation but usually less durability.

This roofing option comes in various types:

• Asphalt-saturated felt roll – Economical but less durable
• Modified bitumen roll roofing – More flexible and long-lasting
• Fiberglass reinforced roll roofing – Stronger and resistant to cracking

Can Roll Roofing Be Installed Over Existing Shingles?

Technically, roll roofing can be installed over a shingled roof if certain conditions are met. Building codes in many U.S. states allow up to two layers of roofing materials on residential roofs. Since most shingled roofs have one layer, adding roll roofing would be acceptable where local regulations permit.

However, roofing experts recommend inspecting the current shingles to ensure they are firmly attached and free from major damage. If shingles are curling, broken, or water-compromised, installing roll roofing over them can worsen problems rather than solve them.

Some of the critical factors to consider before installing roll roofing over shingles include:

• Roof slope and drainage performance
• The total weight on the roof structure
• Current roof condition including decking integrity
• Ventilation requirements and how the new layer affects airflow

Ignoring these factors might lead to premature roofing failure or costly repairs.

Benefits of Putting Roll Roofing Over Shingles

Homeowners may choose to install roll roofing over shingles for several reasons:

• Cost savings – It avoids the labor and disposal costs of tearing off old shingles.
• Quick installation – Roll roofing rolls out faster, minimizing disruption.
• Extra water resistance – Adding a layer of roll roofing can provide an additional waterproof barrier.
• Suitable for low-slope roofs – It can improve protection in flat or minimal-slope roof sections.

This approach can be especially attractive for homeowners in need of a fast, affordable roofing solution or for secondary structures like sheds.

Drawbacks and Risks of Installing Roll Roofing Over Shingles

Despite the benefits, there are significant concerns to consider:

• Reduced roof lifespan: Installing roll roofing over damaged shingles can trap moisture and hasten roof deck deterioration.
• Potential ventilation issues: Adding layers may interfere with proper attic ventilation, risking mold and rot.
• Weight concerns: Extra layers add weight to the roof frame, which may not be structurally designed for it.
• Warranties void: Many roofing manufacturers void warranties if roll roofing or additional layers are added over original shingles.
• Aesthetic and resale impact: Roll roofing may not look as visually appealing as traditional shingles, potentially reducing home value.

These risks emphasize the importance of a thorough roof inspection and consultation with roofing professionals before proceeding.

Best Practices for Installing Roll Roofing Over Shingles

When conditions are suitable and local codes permit it, following these guidelines ensures a successful installation:

Inspection and Preparation

• Examine shingles for damage or loose areas and replace any compromised sections.
• Ensure the roof decking is dry, clean, and structurally sound.
• Remove debris, dirt, and loose granules from existing shingles.

Choosing the Right Roll Roofing Material

• Select a high-quality roll roofing product with good UV resistance and durability.
• Consider modified bitumen or fiberglass options for longer lifespan.

Installation Tips

• Start at the low point of the roof and roll the roofing toward the ridge.
• Use roofing nails or staples designed for roll roofing, placing them properly to avoid leaks.
• Overlap seams generously to ensure waterproofing.
• Apply roofing cement or compatible sealant on edges and fasteners.

Ensure Proper Ventilation

Maintain or improve attic ventilation to prevent heat buildup and moisture accumulation, which can damage the roof system.

Alternatives to Installing Roll Roofing Over Shingles

If there are concerns about installing roll roofing over shingles, homeowners may consider other options:

• Remove Old Shingles: Tear off the existing roofing before installing new shingles or roll roofing for a clean and durable base.
• Overlay With New Shingles: Installing a second layer of shingles instead of roll roofing may preserve aesthetics and improve durability.
• Install Metal Roofing: Metal roofing can be installed over shingles and provides superior longevity and weather resistance.
• Use Roofing Membranes: Self-adhered or torch-applied membranes offer robust waterproofing over old roofs.

Cost Considerations and Lifespan Expectations

Roll roofing materials are generally less expensive than shingles, with material costs ranging from $30 to $100 per roll depending on quality. Labor costs are lower due to ease of installation.

However, roll roofing typically lasts 5 to 10 years on residential roofs, shorter than the 20-30 years lifespan of high-quality shingles. When installed over existing shingles, lifespan may further reduce if existing damage is present.

Homeowners should weigh immediate savings against potential earlier replacement needs and maintenance costs.

Summary Table of Key Considerations