When discussing commercial roofing, two terms that often cause confusion are roof crickets and sumps. While both are designed to manage water on flat and low-slope roofs, they perform very different functions. Understanding the difference is important for preventing ponding water, reducing leak risks, and extending the life of a commercial roofing system.
If you’re planning a new roof installation, replacing an aging roof, or troubleshooting drainage issues, knowing how crickets and sumps work can help you make informed decisions.
What Is a Roof Cricket?
A roof cricket is a raised, sloped structure installed on the roof to divert water around an obstruction. It is typically built behind large rooftop penetrations such as HVAC units, skylights, chimneys, or large exhaust equipment.
Instead of allowing rainwater to collect behind these obstacles, a cricket splits the water flow and redirects it toward roof drains, scuppers, or gutters.
Primary Purpose of a Cricket
The main functions of a roof cricket include:
- Preventing ponding water behind rooftop equipment
- Directing rainwater toward drainage points
- Reducing stress on roofing materials
- Minimizing the likelihood of leaks around penetrations
- Helping the roof dry more quickly after storms
Commercial roof crickets are usually constructed using tapered insulation, wood framing, or lightweight insulation systems, depending on the roof design.
What Is a Roof Sump?
A roof sump is a recessed area surrounding an interior roof drain. Rather than raising the roof surface like a cricket, a sump lowers the roofing surface around the drain to encourage water to flow directly into it.
Think of a sump as a shallow funnel built into the roof.
Without a properly designed sump, water may sit around the drain instead of entering it efficiently, especially on low-slope commercial roofs.
Primary Purpose of a Sump
A roof sump is designed to:
- Improve drainage into roof drains
- Eliminate standing water around drains
- Increase drainage efficiency during heavy rainfall
- Reduce long-term moisture exposure near drain assemblies
- Protect roofing materials from premature deterioration
Most modern commercial roofing systems include sumps around internal drains as part of good drainage design.
The Key Difference Between a Cricket and a Sump
Although both components improve drainage, they work in opposite ways.
A roof cricket raises the roof surface to redirect water around obstacles.
A roof sump lowers the roof surface to collect and channel water into a drain.
In simple terms:
- Cricket = pushes water away from obstacles
- Sump = pulls water toward drains
Both may exist on the same commercial roof because they solve different drainage challenges.
Why Both Components Matter
Flat roofs are never perfectly flat. They are designed with slight slopes that encourage water to move toward drainage systems.
Without proper drainage design, water can remain on the roof for extended periods, causing:
- Ponding water
- Membrane deterioration
- Increased structural loading
- Mold and algae growth
- Roof leaks
- Reduced roof lifespan
Crickets and sumps work together with roof slope, tapered insulation, drains, scuppers, and overflow systems to keep water moving efficiently.
When Is a Cricket Needed?
A roofing contractor may recommend installing a cricket when:
- Large HVAC units block water flow
- Skylights create water traps
- Rooftop mechanical equipment interrupts drainage
- Chimneys or walls create dead water zones
- Persistent ponding occurs behind rooftop structures
Building codes often require crickets behind certain large rooftop penetrations because they significantly improve drainage performance.
When Is a Sump Needed?
A sump is commonly installed whenever a roof includes interior drains.
It becomes especially important when:
- Water pools around drains
- Drain openings sit higher than surrounding roof areas
- Roof replacements change insulation thickness
- Drainage performance needs improvement
- Existing ponding occurs near drain locations
Properly constructed sumps help roof drains perform as intended during both routine rainfall and severe storms.
Can a Roof Have Both?
Absolutely.
Most commercial roofs include several drainage features working together.
For example:
- Crickets divert water around rooftop equipment.
- Roof slopes guide water toward drains.
- Sumps collect water at each drain.
- Overflow drains provide backup protection during heavy rain.
This integrated approach minimizes standing water and helps preserve the roofing system for decades.
Shieldline Roofing’s Expert Opinion
Although both roof crickets and sumps manage water, they solve opposite drainage problems. At Shieldline Roofing, we design these features based on the roof’s slope and drainage layout because placing the wrong solution in the wrong location can lead to standing water, premature membrane failure, and recurring leaks.
Our Key Insights
According to the National Roofing Contractors Association (NRCA), ponding water that remains on a roof for more than 48 hours can accelerate membrane deterioration and increase the risk of leaks, making properly designed drainage features like crickets and sumps essential for extending a roof’s service life.
The Bottom Line
Although they sound similar, roof crickets and roof sumps serve different purposes. A cricket redirects water around rooftop obstacles by creating a raised slope, while a sump creates a recessed area that channels water directly into roof drains.
Both components play an important role in effective commercial roof drainage. When designed and installed correctly, they reduce ponding, help prevent leaks, improve drainage efficiency, and extend the lifespan of the roofing system.
If your commercial roof experiences standing water, slow drainage, or recurring leaks, a professional roofing inspection can determine whether poorly designed crickets, inadequate sumps, or other drainage issues are contributing to the problem. Addressing these issues early can help prevent more extensive and costly repairs in the future. Learn More
