Roofing tar, also known as roof mastic or roof cement, is a common material used for sealing and repairing roof leaks. It is a thick, sticky substance that forms a watertight seal when applied to cracks, holes, or damaged areas on the roof. However, one question frequently asked is whether it is possible to apply roofing tar on a damp roof. In this article, we will delve into this topic and provide an in-depth explanation.
Understanding Roofing Tar
Roofing tar is primarily composed of bitumen, a sticky, waterproof substance derived from petroleum. This black, viscous material is mixed with other additives such as fillers, solvents, and fibers to enhance its durability and adhesion properties. Roofing tar is designed to withstand the elements and provide a long-lasting seal, protecting your roof from water infiltration, UV rays, and other environmental factors.
Effectiveness on a Damp Roof
Ideally, roofing tar should be applied on a dry surface to ensure proper adhesion and prevent issues like blistering or peeling. Moisture can interfere with the bond between the tar and the roof, compromising its effectiveness. Applying roofing tar on a damp surface can also trap moisture underneath, leading to further damage and potential mold or mildew growth.
However, there are situations where applying roofing tar on a damp roof might be necessary or unavoidable. In such cases, certain precautions and techniques can help improve the effectiveness of the application.
Preparation and Technique
- Inspection: Before applying roofing tar on any surface, it is crucial to thoroughly inspect the roof for any existing leaks, damaged areas, or potential weak spots. Identifying the underlying issues is essential to address them properly before applying the tar.
- Cleaning: Ensure the roof surface is free from debris, dirt, moss, or any other obstructions. A clean surface will allow for better adhesion and improve the success rate of the tar application. Use a broom or a soft brush to remove loose debris and a pressure washer or a garden hose to clean the surface thoroughly.
- Drying: Although the roof may still be damp, it is essential to allow it to air dry as much as possible before applying the roofing tar. Avoid applying tar during rainy or humid weather conditions, as it will hinder the drying process. Installing tarps or protective covering can help prevent further moisture accumulation.
- Priming: Priming the damp roof surface can enhance the bond between the tar and the roof. Using a quality primer specifically designed for damp surfaces will promote better adhesion, sealing any remaining moisture and providing an extra layer of protection.
- Application: When applying roofing tar on a damp roof, it is recommended to use a thicker layer than usual. This will compensate for the potential lack of adhesion caused by the moisture. Ensure that the tar is spread evenly and covers the intended area entirely.
While it is generally advisable to apply roofing tar on a dry surface to ensure optimal adhesion and performance, there are circumstances where dealing with a damp roof might be necessary. By following the appropriate techniques, including thorough inspection, cleaning, drying, priming, and a slightly thicker application, you can improve the chances of a successful seal. However, it is essential to keep in mind that addressing the underlying cause of moisture accumulation should be a priority to prevent future issues and potential damage to your roof. In case of extensive damage or persistent leaks, it is recommended to consult a professional roofing contractor to assess and address the situation effectively.