Reflective Coatings: Impact on Interior Temperatures and Roof Durability

Have you ever wondered if applying a thin coat of whitewash or reflective coatings on an asphalt shingle roof can reduce interior temperatures and bolster weathered shingles? Let's delve into this concept and explore its validity, potential benefits, and limitations.

The Science Behind Reflective Coatings

The idea that applying a thin coat of whitewash or reflective coatings on an asphalt shingle roof can reduce interior temperatures is based on the principle of reflectivity. White or light-colored surfaces reflect more sunlight compared to dark surfaces which absorb heat. While the exact temperature drop can vary based on several factors including climate, roof orientation, and the specific materials used, some studies and anecdotal evidence suggest that reflective coatings can indeed lead to noticeable reductions in cooling costs and interior temperatures—potentially in the range of 10 to 20 degrees Fahrenheit in some scenarios.

Impact on Roof Durability

Reflective coatings not only help mitigate heat absorption but also protect weathered shingles, which typically contain a mineral base often including limestone. Whitewashing can help shield shingles from UV degradation and reduce heat absorption, which can improve their lifespan. However, it is important to note that the effectiveness can vary. The application of whitewash could potentially seal and protect the shingles but may not restore them to their original condition, especially if they are significantly weathered or damaged.

Additional Considerations: EPDM Coatings

EPDM coatings, also known as liquid rubber, are another type of reflective coating. These coatings come in a white finish and can benefit a building and its occupants by decreasing energy bills through the reduction of air conditioning. Moreover, EPDM coatings are environmentally safe, which cannot be said about many other roof coatings available on the market.

Bolstering Shingles: An Additional Layer of Protection

While reflective coatings can help protect shingles, their impact on bolstering them mainly lies in their ability to extend the roof's life. However, the claims about reducing internal temperatures need careful examination. For an optimal cooling effect, the roof should be completely white and the shingles in excellent condition. In typical scenarios, the difference in temperature reduction is much smaller.

For comparison, smartphones will tout a battery life of 3 days, but this is only achievable when the screen and apps are not used. Similarly, the temperature shift achieved by reflective coatings is most noticeable in ideal conditions, such as a completely white, weathered roof in a climate zone with low temperatures.

Conclusion

While there is merit to the claim that whitewashing and reflective coatings can improve roof reflectivity and potentially reduce interior temperatures, the exact benefits can vary. It is essential to consider the condition of the shingles before applying any coating. Additionally, reflective coatings like EPDM can offer significant benefits in terms of energy efficiency and longevity while being environmentally friendly.