What is a Pitch Pocket on a Roof?

A pitch pocket is a type of specialty roof flashing used to seal small or irregular roof penetrations on both sloped and flat roofs. Pitch pockets provide a watertight barrier around penetrations such as plumbing vents, electrical conduits, structural supports, and more.

Properly sealing any roof penetration is crucial to prevent leaks and moisture damage. However, not all penetrations can be easily flashed with standard boots or metal flashing. This is where pitch pockets come in.

Key Takeaway: Pitch pockets act as containers to hold sealant around penetrations that are difficult to flash any other way.

What Does a Pitch Pocket Do?

A pitch pocket serves two key functions:

  • Creates a sleeve to fit around irregularly shaped penetrations.
  • Holds the sealant needed to waterproof the penetration area.

Without a pitch pocket, there would be no good way to seal small, angled, or odd-shaped penetrations on a roof. The pitch pocket contains the sealant and bonds it to the roof membrane and penetration.

Key Takeaway: Pitch pockets waterproof tricky roof penetrations by holding a flexible sealant that forms around them.

Pitch Pocket Design and Shape

Pitch pockets are most commonly made of sheet metal, such as:

  • Galvanized steel
  • Aluminum
  • Copper

They can also be molded from polymers like PVC or TPO.

The classic pitch pocket shape resembles a top hat. It’s open at both the top and bottom. This allows it to slip over a roof penetration and surround it on all sides.

There are two main components to a pitch pocket’s design:

Vertical Sleeve

The vertical walls form a sleeve to encapsulate the roof penetration. The sleeve should be tall enough to extend several inches above and below the penetration. This provides space for sealant above and an adequate flange below.

Bottom Flange

The bottom of the pitch pocket flares out into a wide flange. This flange gets bonded to the roof membrane with adhesives, fasteners, or heat welding. A larger flange provides more surface contact and security.

Some pitch pockets also include a top flange or cap for additional weather protection.

Key Takeaway: Pitch pockets are flanged, open-bottomed sleeves made of sheet metal or molded plastic.

Typical Pitch Pocket Shapes

There are several common pitch pocket shapes:

  • Round – For single pipe penetrations.
  • Square – For small square penetrations.
  • Rectangular – For long or clustered penetrations.
  • Custom – Fabricated for unique needs.

Rectangular pitch pockets are commonly used for multiple electrical conduits or drainage scuppers. Custom pitch pockets can be made in just about any shape using sheet metal.

What Are Pitch Pockets Used For?

Pitch pockets have many applications across all roof types. Some examples include:

  • Electrical – Conduit, wiring, junction boxes.
  • Plumbing – Drainage scuppers, vents, valves.
  • HVAC – Ductwork, unit supports, condensate lines.
  • Structural – Beams, columns, equipment bases.
  • Miscellaneous – Satellite dishes, antennas, signs.

They are an essential flashing option for difficult to seal roof penetrations.

Pitch Pocket Locations

Pitch pockets can be installed anywhere on a roof that requires watertight sealing around a penetration. Some common locations include:

  • Penetrations along the roof perimeter.
  • Rooftop HVAC equipment – curling, ductwork.
  • Skylights or other protrusions.
  • Field penetrations away from edges.

Avoiding roof penetrations altogether is ideal. But when unavoidable, proper flashing is a must.

Why Are Pitch Pockets Used?

There are several reasons why pitch pockets are needed in certain situations:

  • Irregular shape – Won’t fit standard flashing.
  • Small size – Too small for flashing boot.
  • Angle – Penetrates roof at odd angle.
  • Clustered – Too close together for multiple flashings.
  • Flexibility – Allows for expansion and contraction.
  • Quick installation – Bolt on and seal up.

The watertight sealant compensates for difficult to flash attributes.

Pitch Pocket vs Standard Flashing

For standard pipe boots and other flashings to work, the penetration must have:

  • Adequate surface area for adhesion.
  • Straight, vertically oriented sides.
  • Room between clustered penetrations.

Without these conditions, specialty pitch pocket flashing is needed.

How Does a Pitch Pocket Work?

A pitch pocket provides a watertight seal through this simple process:

  1. Slip pitch pocket over roof penetration.
  2. Secure flange to roof membrane.
  3. Fill pitch pocket with sealant.
  4. Sealant adheres to all sides.
  5. Excess sealant sheds water.

This seals the roof opening around the penetration.

Proper installation is crucial for pitch pockets to work effectively long-term.

Pitch Pocket Sealants

The sealant used inside a pitch pocket depends on roof type:

  • Asphalt – Hot asphalt or asphaltic cement for BUR roofs.
  • Mastic – Mastic, asphalt, or roofing cement for modified bitumen.
  • Pourable sealer – Urethane, acrylic, or silicone sealers for TPO, PVC, EPDM.

It is critical to use compatible sealants to prevent chemical reactions and adhesion loss. Consult the roofing manufacturer when selecting pitch pocket sealants.

How are Pitch Pockets Installed?

Proper pitch pocket installation involves several key steps:


  • Clean roof membrane.
  • Prime surfaces for adhesion.
  • Test fit pitch pocket.


  • Secure flange to roof membrane.
  • Seal corners and seams.
  • Mix and fill sealant.


  • Tool sealant to proper shape.
  • Install storm collar.
  • Seal and secure storm collar.

Key Takeaway: Correct pitch pocket installation is vital for proper sealing and roof protection.

Why Do Pitch Pockets Fail?

When installed improperly or left unmaintained, pitch pockets can become sources of major roof leaks. Common causes of failure include:

  • Improper sealant selection.
  • Inadequate sealant filling.
  • Lack of roof membrane cleaning and priming.
  • Sealant drying, cracking, shrinking.
  • Structural movement or vibration.
  • Damage from weather, sun exposure.

Annual inspections and maintenance can prevent most pitch pocket failures.

Pitch Pocket Maintenance

To prevent leaks, pitch pockets should be inspected at least twice per year and after major storms. Look for:

  • Shrinkage or cracks in sealant.
  • Gaps between sealant and penetration.
  • Damage or deterioration to pitch pocket.
  • Improperly secured flange or storm collar.
  • Signs of interior water damage.

Make any necessary repairs immediately to avoid bigger issues.

How to Maintain Pitch Pockets

Here are tips for properly maintaining pitch pockets:

  • Clean out old sealant and prime surfaces.
  • Reseal with compatible sealant, overfilling slightly.
  • Shape sealant to shed water.
  • Check flange and storm collar attachments.
  • Replace any deteriorated pitch pockets.
  • Address movement issues if chronic failures occur.

Proactive maintenance greatly extends the service life of pitch pockets.

Pitch Pocket Alternatives

For suitable applications, other more reliable flashing options should be considered first.

Roof Penetration Alternatives

  • Route conduits through curb bases when possible.
  • Penetrate at drain sumps instead of flat roof sections.
  • Group penetrations together when allowed.

Flashing Alternatives

  • Lead pipe flashings.
  • Flexible rubber boots.
  • Molded roof penetration flashings.
  • Surface-mounted conduit fittings.

Limit Pitch Pocket Use

Pitch pockets should be limited to only essential applications. Each one added to a roof increases the likelihood of eventual leakage.

Key Takeaways on Pitch Pockets

  • Pitch pockets provide sealant-filled flashing for irregular roof penetrations.
  • Proper product selection and installation is crucial for pitch pockets to work effectively.
  • Regular inspections and maintenance prevents most pitch pocket failures.
  • Limit pitch pocket use to applications where other flashings won’t work.

Frequently Asked Questions

Below are answers to some common questions about pitch pockets.

Where are pitch pockets required?

Pitch pockets are required wherever a watertight seal is needed around a roof penetration that cannot be properly flashed any other way. This most often includes small, angled, or clustered penetrations.

What size pitch pocket do I need?

The pitch pocket must be large enough to fit over the penetration with room for sealant on all sides. It also needs an adequate flange width for proper roof membrane adhesion. Allow 2-3 inches of clearance around the penetration.

How much sealant goes in a pitch pocket?

Fill the pitch pocket with enough sealant to make contact on all sides of the penetration. Also overfill slightly so excess sealant will shed water. Avoid filling more than halfway up the vertical sleeve.

Do pitch pockets require maintenance?

Yes, pitch pockets should be inspected at least twice per year and resealed as needed. Old sealant will eventually crack and shrink, allowing leaks. Regular maintenance is crucial.

How long should pitch pockets last?

When properly installed and maintained, quality pitch pockets should last 15-25 years. Eventually the metal will corrode and require full replacement.


Pitch pockets provide important protection for roof penetrations that can’t be sealed any other way. However, they must be properly selected, installed, and maintained to work as intended long-term. Limit pitch pockets only to essential applications. For general use, standard flashing options are more reliable and leak-proof. But when you need them, be sure to make pitch pockets a priority for regular roof inspection and maintenance.