Can You Apply Roof Coating on Asphalt Shingles? Best Practices and Considerations

Homeowners often explore roof coatings as a cost-effective way to extend their roof’s lifespan. A common question is, can you put roof coating on shingles? The answer depends on several factors including the type of shingles, roof condition, and the coating material. This article delves into the practicalities, benefits, and limitations of applying roof coatings on asphalt shingles, designed to help homeowners in the U.S. make informed decisions.

How Roof Coatings Work and Their Typical Uses

Roof coatings form a protective layer that extends the lifespan of roofing materials by sealing minor cracks and reflecting sunlight. They are typically applied to flat or low-slope roofs with materials such as metal, concrete, or modified bitumen membranes. Their main benefits include increased waterproofing, energy efficiency, and UV protection.

However, roof coatings are not universally suitable for all roofing types, particularly those with complex textures or steep slopes like asphalt shingles. Homeowners need to understand these factors before applying any coating products.

Are Asphalt Shingles Suitable for Roof Coatings?

Asphalt shingles are among the most common residential roofing materials in the U.S. Their textured, granular surface and layered design create challenges for a long-lasting roof coating application. Most manufacturers do not recommend coatings for conventional asphalt shingles due to these reasons:

• Granule Loss: Shingles naturally shed granules over time, which is incompatible with smooth coating adherence.
• Expansion and Contraction: Shingles flex with temperature changes, risking coating cracking or peeling.
• Drainage Patterns: Shingles require specific water drainage that coatings may impede.

Despite these challenges, some specialized elastomeric coatings can be applied to shingles if the roof is in good condition and properly prepared.

Best Types of Roof Coatings for Asphalt Shingles

When selecting roof coatings for asphalt shingles, homeowners should focus on products specifically formulated for such applications. The primary types include:

• Elastomeric Coatings: These flexible coatings stretch and contract with the shingles, providing waterproofing and UV resistance. They are the most recommended for asphalt shingle roofs.
• Acrylic Coatings: Popular for their UV reflectivity and drying speed, but less flexible, hence only suitable on newer roofs with minimal movement.
• Silicone Coatings: Excellent waterproofing but tend to adhere poorly on shingles and can make surfaces slippery, so less popular for shingle roofs.

Preparing Shingled Roofs for Coating Application

Proper preparation is key to the success of any roof coating application on shingles. This includes:

• Cleaning: Remove dirt, moss, and loose granules using a soft brush or low-pressure washing. Avoid high pressure to prevent damage.
• Repairing: Replace or fix damaged, curled, or missing shingles before coating.
• Priming: Some coatings require a primer layer to improve adhesion on granulated surfaces.
• Drying Time: Ensure the roof is completely dry to avoid moisture trapping.

Failing to properly prepare the roof can lead to peeling, bubbling, or short coating lifespan.

Application Guidelines and Techniques

Following manufacturer guidelines helps achieve the best results. General application steps include:

1. Apply the coating on a clear, dry day with temperatures between 50°F and 85°F.
2. Use brushes, rollers, or spray equipment designed for elastomeric roof coatings.
3. Apply evenly in thin layers to avoid pooling or runs.
4. Allow adequate drying time (often 24-48 hours) between coats; two coats are typically recommended.
5. Inspect the roof after application for missed areas or imperfections.

Proper application can enhance the roof’s waterproofing and energy-saving properties while minimizing risks common to shingle coatings.

Advantages and Disadvantages of Coating Asphalt Shingles

When to Avoid Applying Roof Coatings on Shingles

Roof coatings are not suitable for every shingle roof. Avoid coatings if:

• The roof has significant damage such as cracked, buckled, or missing shingles.
• Shingles are older than 10-15 years and showing considerable wear or granule loss.
• There are underlying structural issues or leaks that require repair.
• The roof experiences heavy foot traffic or snow loads leading to constant flexing.

In such cases, roof replacement or alternative repair methods may be more cost-effective and safer.

Maintenance Tips for Coated Shingled Roofs

Once coated, shingle roofs still need periodic upkeep to maintain their protection:

• Inspect the roof annually for cracking, peeling, or discoloration of the coating.
• Clean debris and moss off the surface carefully to avoid damaging the coating.
• Reapply coating every 5-7 years or as recommended by the product manufacturer.
• Address any minor damage immediately to prevent water infiltration.

Regular maintenance ensures the roof coating remains effective and prolongs the roof’s overall life.

Cost and ROI of Applying Roof Coating on Asphalt Shingles

The cost of roof coatings varies depending on size, material, and labor, generally ranging from $1.50 to $3.50 per square foot. Compared to a new asphalt shingle roof installation ($5-$7 per square foot), coating is a more affordable option.

However, the return on investment depends on the roof’s condition and proper application. When done correctly, coatings can extend roof life by 5-10 years, providing significant savings on premature roof replacement.

Summary