Find the best flashing for your roofing project based on roof pitch, material, and environment.

Choosing the right roof flashing might not be the most exciting part of a project, but it's an important step that should not be overlooked. A properly flashed roof helps protect against leaks, rot, and costly repairs down the line.

This guide is here to make choosing the right flashing as simple as possible. With the tips included, you can find a flashing option that fits yours needs, your roof, and your budget.

The key factors to consider when selecting flashing include:

• Flashing location and size: pipe, chimney, roof valley, skylight, etc.
• Roof material, pitch, and profile
• Durability and weather exposure
• Budget and timeline

See the table below for comparisons of top flashing options across these key factors: 

Before You Buy

It's always wise to confirm your project requirements before buying new hardware for any job. In roof flashing, this might include checking pipe size (for flashing pipe penetrations), roof pitch, and roof material and profile. Each of these factors affects how well flashing seals to your roof. 

Pipe Size

If you are flashing a pipe penetration, using the correct size is essential. Premade pipe flashings fit a range of sizes, and it's important to find one that fits your pipe.

Check out the table below to see which premade flashing options will fit your pipe, and remember: in flashing, pipes are measured by their outer diameter.

If you are flashing something that is not round or exceeds the largest size available in the premade flashing options, a linear flashing roll may be best for your project.

Roof Pitch

The next factor to consider is the pitch, or steepness, of your roof. This is the angle of the roof's incline. This is especially important to know when flashing a pipe penetration, but it is useful in any project.

Most roofs have a pitch between 18° and 36°, but specialty flashing options, such as the Dektite Soaker or the Dektite High Pitch flashings, can accommodate roofs with a steeper pitch. Linear flashing products like Fast Flash or Dekstrip offer additional adaptability as they can flex to fit nearly any angle.

Use the table below to compare flashing options and the range of roof pitches they support.

Measuring Roof Pitch

If you don't know the pitch of your roof, you can find it with just a level and a tape measure.

1. Find the length of your level. 
2. Place one end of the level on the roof. 
3. Holding the level parallel to the ground, measure the vertical distance between the far end of the level and the roof beneath it. 
4. Divide the vertical distance by the length of the level.
5. Convert the result into a fraction with a denominator of 12. 

Example: If the vertical distance is 8 inches and the level is 24 inches long:

8 ÷ 24 becomes 4 ÷ 12, so the roof pitch is 4/12

Watch this video for more help. 

Roof Material & Profile

Finally, be sure to use flashing that fits your specific roof material and shape. This will help ensure a proper seal and long-term performance.

Use the table below to see which roofing materials are compatible with various flashings.

The roof profile, or the shape of its surface, is also helpful to consider. Flashings with large bases are better at flexing around deep contours, making them suitable for roofs with pronounced seams or ridges.

Material Matters

When you've found the flashing style you need, the next decision is the flashing material. Most flashings are available in both silicone and EPDM rubber. Which one is right for you depends on the environment, intended use, and budget.

Silicone flashings typically cost more than EPDM rubber, but they offer greater durability, weather resistance, and overall longevity. Upgrading to silicone isn't always necessary if your project does not involve extreme heat or weather exposure. For quick repairs and most standard applications, EPDM flashings are a reliable and cost-effective option.

Key Differences

Silicone has greater temperature tolerance than EPDM rubber:

• Silicone: -58℉ (-50℃) to 392℉ (200℃). Ideal for high-temperature exhaust systems, steam lines, and ovens or furnaces. 
• EPDM Rubber: -58℉ (-50℃) to 239℉ (115℃). Great for lower-heat applications such as HVAC vents or plumbing stacks. 

EPDM rubber is more vulnerable to prolonged exposure to:

• UV radiation, which can cause embrittlement over time. 
• Ozone, which can lead to surface cracking. 
  
• High heat, which reduces elasticity and strength. 

Why This Matters

While EPDM rubber outperforms many standard rubber options, it has limits that silicone exceeds. If your flashing will be exposed to high heat, harsh weather, or high elevation, silicone is a more sustainable long-term choice. EPDM flashings in high-exposure environments may require more frequent repairs or replacements.

Quick Picks

Not sure where to start? Check out a few of the most popular flashing products and see what makes them unique.

Dektite Original

Most popular choice

The Dektite Original pipe flashing is the go-to option for most standard applications. It can be fitted to the most pipe sizes and roof pitches, and it's available in silicone, EPDM, and a variety of color options.

Dektite Soaker

More flexibility

The Dektite Soaker-Diverter flashing features a large square base that provides added flexibility on high-pitched roofs and around deep roof profiles. Square base flashings allow for easier application on standing seam or corrugated roofs.

Linear Flashing Rolls

Versatile and flexible

Linear flashing rolls such as the Dekstrip Flexible Pipe Flashing and Dektite Fast Flash are ideal for projects that don't fit other premade flashing options.

Dekstrip Flexible Pipe Flashing provides a secure seal across a wide variety of surfaces and penetrations, and Dektite Fast Flash has an adhesive backing, making it a fast and efficient choice for repairs and quick fixes.

How linear flashing offers unmatched adaptability:

• Seals penetrations and surfaces of nearly any shape and size.
• Compatible with a wide range of roofing materials.
• Compatible with nearly any roof pitch or profile.

Retrofit & Dektite Combo

Ideal for repairs or replacements

For replacing existing flashing or working around hard-to-reach pipes, the Retrofit Original and Dektite Combo are excellent choices. These flashings can be installed and sealed around an existing penetration instead of over it, making the process quicker and easier.

Dektite Ezi-Seal

Self-sealing

The Dektite Ezi-Seal flashing features a watertight sponge gasket that seals directly to the roof surface. This design eliminates the need for extra silicone sealants, making it a fast and easy option.

Key Comparisons

The right flashing for your project depends on many factors, including pipe size, roof design, budget, and timeline. Although there are a multitude of options to consider, finding the right flashing can be easy if you know what your project needs.

Use the table below for a final overview of all the information we covered in this guide, and explore our storefront to see all available flashing products.

If you have further questions or need help with your project, don't hesitate to contact us at (406)752-5253 or email us at tom@jakesales.com.