The Best Roof Sealants: How to Repair Roof Leaks

A ceiling drip can be a stressful sight. It is vital that you select a roof sealant that is specially formulated to withstand harsh weather conditions so you can rest assured it will protect your roof. Elements such as rain, ice, and sunlight can wreak havoc on exterior roof joints and surfaces. In this guide, we explain how to find leaks and properly seal them.

There are many available options for roof sealants but you have to be thorough in comparing each product to find the right fit for your project. Sealants come in different types. The most common are acrylic, silicone, and polyurethane.

Acrylic and polyurethane are two sides of a coin. Acrylic sealant formulations are great for protecting a roof from sun damage but don’t do well in handling moisture while polyurethane sealant formulations are strong against water damage but are weak against UV rays from the sun. Silicone sealant formulations, on the other hand, are resilient against both moisture and UV rays but can be quite expensive.

If you are in an area where rain is frequent, opt for silicone or polyurethane. Most products will offer protection against water but not all of them are completely waterproof so be sure to check the label. Some products would also require multiple coatings to achieve complete waterproofing.

It is important to note that roof sealants are the best solution for small to mid-sized applications for diverting water or plugging holes and cracks; large damaged areas may require a more complex repair. Always consider the size of the project before making your decision.

Finding the source of a roof leak can be challenging, but it is vital. First, assess where the leak is located in your home. Remember, water may travel from a different location depending on the architecture.

If you need to access your attic, move carefully and ensure you have secure footing, as surfaces can be uneven or slippery. Use appropriate lighting and take caution when navigating around insulation or structural elements.

Once you have an idea of where the leak is coming from, the safest option is to go up into your attic space. Look for black areas or mold because they are typically strong indicators of water leaks. Go outside and check the shingles/roofing in that area. In flat sections of the roof, keep an eye out for misplaced shingles, standing water, mold buildup, or rotting sections.

The most common type of roof leak is caused by an object that penetrates the roof, such as your chimney, roof vents, or anything else that passes directly through the roof. Small gaps and holes can typically be repaired with a roof-appropriate exterior sealant designed to handle movement and weather exposure.

After you have identified the source of a small leak, you can begin filling it with roof caulk. For larger repairs, you can use the sealant on new joints and materials as needed. Before application, ensure that the joint you wish to apply sealant to is dry, clean, and free of any debris. It should also be structurally sound. Although the sealant is flexible, it is not intended to serve as an adhesive.

Steps for repairing a roof leak with caulk:

1. Gather the required tools - You will need a razor blade, gloves, a caulking gun, and sealant.
2. Ensure the area is in good condition and not rotting - Replace all rotting wood with new material.
3. Identify the problem - Look for tears and cracks in existing sealant, because this is normally the cause of most roof leaks.
4. Clean the area - Ensure that the area is free of old caulk, moisture, loose particles, asphalt, tar, paint, wax, and rust. To remove the old compound, use a razor blade and acetone spray. Wear gloves to protect your hands.
5. Surface preparation - In areas exposed to incidental water, a primer may be recommended, depending on the product. Always follow the instructions on the label.
6. Application - It is important to apply the sealant with steady pressure, forcing it into the joint. Protect open products and tools from direct sunlight for the best results. Use together with a closed cell backer rod for joints deeper than 13mm to avoid 3-sided adhesion. The depth of the sealant should be half the width of the joint. The maximum depth is 13mm, and the minimum is 6mm.

Selecting the right sealant for the job is critical. Over time, structures shift and flex, so it’s important to choose a roof sealant that can accommodate movement without tearing or ripping. Look for products specifically formulated for roofing applications that offer long-term protection against harsh weather conditions.

For general seals around the home, LePage No More Nails Heavy Duty can handle many interior and exterior projects. It bonds effectively to a wide range of construction materials such as wood, drywall, concrete, masonry, and brick.

Wondering if a multipurpose silicone-based sealer might do the trick as well? The answer is no. Silicone caulks are a good choice for indoor projects that require sealing.