Roof Leak Risks in Royal Oak: Why AC Unit Flashing Cannot Be Overlooked

For homeowners in Royal Oak, Michigan, keeping a roof in excellent condition is essential. One often-overlooked area that can cause significant problems is the flashing around rooftop air conditioning units. Many homeowners focus on the appearance of their roofs or the efficiency of their HVAC systems but fail to consider how critical proper flashing is to preventing leaks. In Southeast Michigan, where weather swings from heavy snow and ice in winter to intense sun and rain in summer, even small mistakes in flashing installation can lead to serious water damage. Understanding roof leak risks in Royal Oak and how to prevent them is crucial to protecting your home and your investment.

Why AC Unit Flashing Matters for Your Roof

Flashing refers to thin strips of metal installed around roof penetrations, such as chimneys, vents, skylights, and HVAC curbs. Its main purpose is to create a watertight barrier where the roof surface is interrupted. Without properly installed flashing, water can seep under shingles or roofing membranes, leading to leaks, rot, and mold inside your home.

For rooftop AC units, the stakes are even higher. These units sit on curbs that elevate them above the roof surface. The edges of these curbs are exposed to rainfall, snow, and melting ice. Base flashing, which wraps around the curb, acts as the first line of defense. Counter-flashing, installed over the base flashing, provides a secondary layer that directs water away from seams and joints. When either of these is missing, improperly installed, or poorly sealed, the risk of water infiltration increases dramatically.

Even minor gaps in flashing or missing sealant can allow water to penetrate the roof deck. Once water gets in, it can pool around the AC curb, eventually causing damage to the roofing materials, the structure beneath, and even the interior ceilings. These risks are heightened in Michigan because seasonal freeze-thaw cycles create expansion and contraction in roofing materials. A small crack or loose seam in flashing can widen over time, leading to leaks that are costly to repair.

Real-Life Examples Highlighting the Risk

A recent TikTok demonstrates the risks clearly. The video shows a rooftop AC unit with base flashing installed incorrectly and completely lacking counter-flashing and waterproof sealant. Water can easily seep between the curb and roof surface. A local roofing expert in the video emphasized that poor flashing around AC platforms often leads to leaks inside ceilings or walls.

This example highlights a critical point for homeowners in Royal Oak: even when a roof appears sound, improper AC flashing can undermine the integrity of the entire system. Many people assume that their shingles or membranes are enough to prevent water infiltration, but without properly installed flashing, roofing materials alone cannot provide complete protection.

Common Roof Leak Risks in Royal Oak Linked to AC Units

Several factors make rooftop AC units a high-risk area for leaks in Southeast Michigan:

1. Freeze-Thaw Cycles
   During winter, water can seep under improperly sealed flashing and freeze. Ice expands, pushing apart roofing materials and worsening small gaps. As a result, leaks can develop beneath shingles or membranes, often going unnoticed until damage becomes severe.

2. Heavy Snow and Ice Loads
   Royal Oak frequently experiences heavy snow accumulation. Snow that melts and refreezes around an AC unit can pool at flashing seams, accelerating wear and causing water penetration.

3. Wind-Driven Rain
   Michigan storms often bring rain that hits the roof at an angle, forcing water into small cracks or gaps in flashing. AC units with exposed seams or missing counter-flashing are particularly vulnerable.

4. Sun and Heat Exposure
   In summer, the sun can cause roofing materials and sealants to expand and contract. If sealant around the AC curb is poor or has cracked over time, water can seep in during storms.

5. Neglected Maintenance
   Many homeowners never inspect rooftop AC flashing unless a visible leak appears inside. Over time, small issues grow into significant problems that are expensive to fix.

Preventing Roof Leak Risks in Royal Oak

Fortunately, there are clear steps homeowners can take to reduce the risk of leaks around rooftop AC units. Regular inspection and proper installation are essential.

1. Schedule Routine Inspections

Inspect your roof at least twice a year and after major storms. Look closely at the flashing around AC units. Homeowners can check for loose edges, gaps, missing counter-flashing, and deteriorating sealant. Professional roofing contractors in Royal Oak can perform detailed inspections, including checking the underlying structure for hidden damage.

2. Ensure Proper Flashing Installation

When installing a new AC unit or replacing an old one, make sure your contractor uses both base flashing and counter-flashing. The base flashing should wrap around the AC curb completely, with corners and joints sealed carefully. Counter-flashing should overlap the base flashing to direct water away from potential penetration points.

3. Use High-Quality Sealants

Even the best flashing needs support from durable sealant. Sealants prevent water from seeping into seams, especially in areas prone to movement due to temperature fluctuations. Silicone-based or polyurethane roofing sealants are often recommended for long-term protection.

4. Protect the Roof Surface

Make sure shingles, membranes, or other roofing materials integrate properly with flashing. Poor alignment or improper overlap can render flashing ineffective. Installing protective barriers or flashing boots can add an extra layer of defense against leaks.

5. Schedule Pre-Winter Maintenance

Michigan winters are harsh, so it’s wise to inspect AC flashing before winter sets in. Address any cracks, loose flashing, or deteriorated sealant early. This reduces the risk of water infiltration during ice, snow, and freeze-thaw cycles.

6. Hire Experienced Contractors

Flashing around rooftop AC units is a specialized task. Experienced contractors know how to install base and counter-flashing correctly and select the appropriate sealants. Choosing a licensed, insured, and local contractor in Royal Oak ensures work meets both industry standards and local building codes.

The Cost of Ignoring Flashing Issues

Ignoring flashing problems can lead to serious and expensive consequences. Water that enters near an AC curb can damage:

• Roof decking, leading to sagging or rotting boards

• Insulation, reducing energy efficiency

• Ceilings and walls inside the home, resulting in mold and structural issues

• HVAC equipment, potentially causing costly repairs or replacement

In severe cases, long-term water exposure can require a full roof replacement, costing tens of thousands of dollars. In contrast, addressing flashing issues proactively is far more cost-effective and preserves the lifespan of both your roof and AC system.

Additional Considerations for Homeowners

Beyond flashing, homeowners should also be aware of related roof leak risks in Royal Oak:

• Gutter and Downspout Integration: Ensure that gutters direct water away from AC curbs and roof edges. Blocked gutters can create backflow that undermines flashing.

• Roof Slope and Drainage: Flat or low-slope roofs are especially prone to water pooling around AC units. Proper drainage systems minimize risk.

• Debris Accumulation: Leaves, branches, and other debris can trap water against flashing and accelerate wear. Regular cleaning reduces risk.

Conclusion

Rooftop AC units are essential for comfort, but they can also introduce significant roof leak risks in Royal Oak if flashing is ignored. Base flashing, counter-flashing, and high-quality sealants are critical components that protect both the roof and the interior of your home. Regular inspection, proper installation, and proactive maintenance are the keys to preventing water damage and extending the life of your roof.

If you notice leaks around your AC unit or suspect flashing issues, contact a trusted local roofer or HVAC professional immediately. Taking action now can save thousands of dollars and protect your home from serious water damage in the future. Your roof is your first line of defense against Michigan’s unpredictable weather, and proper AC unit flashing ensures it stays that way.

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Make sure to check out our recent blog post about Roofing Shapes and Design