Can a Liquid Roof Be Applied Over Asphalt Shingles?

The application of liquid roof coatings directly over asphalt shingles is generally not advisable. While certain conditions and products may allow for such an application, it is crucial to understand the potential risks involved.

Understanding the Risks

Applying liquid roof coatings directly over asphalt shingles without proper preparation can lead to several issues, including the trapping of moisture. This can cause further damage to the shingles and compromise the overall integrity of the roof.

Is Applying a Liquid Roof Over Asphalt Shingles Possible?

While it is technically possible to apply a liquid roof over asphalt shingles, several factors need to be considered:

Surface Preparation

The asphalt shingles must be:

Clean Dry Free from debris Any loose or damaged shingles should be repaired or replaced before application

Compatibility

Ensure that the liquid roofing product is compatible with asphalt shingles. Asphalt shingles are made from asphalt, and some liquid roofing products may not adhere properly or could react negatively with the shingles.

Manufacturer's Instructions

Always follow the manufacturer's guidelines for both the liquid roofing material and the asphalt shingles. This includes any specific preparation or priming steps that may be necessary.

Weather Conditions

Apply the liquid roof in suitable weather conditions, avoiding extreme temperatures or high moisture levels. Poor weather conditions can affect the adhesion and effectiveness of the liquid roof coating.

Warranty Considerations

Check if applying a liquid roof over shingles affects any existing warranties on the shingles. Some manufacturers may void warranties if this method is used.

Proper Drainage

Ensure that the roof has proper drainage to avoid water pooling. This can compromise the integrity of the liquid roof and lead to further damage.

Is Liquid Roof Coating Suitable for Flat Roofs?

Yes, liquid roof coatings are commonly used on flat roofs to provide a waterproof barrier and extend the life of the roofing system. However, they are not typically recommended for use over asphalt shingles due to the reasons mentioned above.

Common Misconceptions

Some sources may recommend applying a liquid roof coating over asphalt shingles, which can be misleading. These sources often confuse liquid roofing with other types of coatings or coatings that are not specifically designed for asphalt shingles.

Surface Incompatibility

Asphalt shingles have granules that naturally separate over time, making them an improper surface for liquid roofing products. The granules can lose their bond to the shingles, leading to poor adhesion and effectiveness of the coating.

Blockage of Asphalt

Over time, asphalt shingles can leach into the coating, making it less effective. Most liquid roof coatings are not compatible with asphalt, which can cause the coating to deteriorate or fail.

Long-Term Durability

Many liquid roof coatings do not provide long-term protection and may only last for a few months or years. This can be a significant expense if applied over an improper surface.

Conclusion

While there is a possibility of applying a liquid roof coating over asphalt shingles, it is crucial to consider the potential risks and ensure proper preparation. It is often better to apply liquid roof coatings on surfaces specifically designed and recommended for such applications, such as metal roofing or flat roofs. Consulting with a professional roofing contractor can help ensure that your roof is properly maintained and extended in its lifespan.