There are countless reasons to have a metal roof installed. Theyíre durable, tough (can withstand elements), and require less maintenance.
A properly installed metal roof can last for decades (typically 40 to 70yrs) and will even sustain 95% of its reflective and emittance properties. But metal roofs are not indestructible. They can still develop leaks, even if the best installation protocols are followed.
Given the tough nature of metal roofs, itís hard to believe they could cause leakage. However, leaks do happen for many reasons. This guide will explore the common causes of metal roof leaks. Letís dive in!
1. Roofing Screw Problems
Roofing screw problems are the top reason youíre likely to experience a roof leak. Metal roofing screws typically keep water out with a rubber washer at the base of each screw head.
When a screw is drilled down into the roof, it should seal the roofing panel such that no gap is left between the panel and the screw head. However, problems can occur in the process leading to leakage. Common roof screw problems result from:
- Overdriven screws
- Under driven screws
- Misaligned screws
- Screws missing the metal strut or wood framing
Over Driven Screws
In an effort to ensure the seal is tightly placed, many homeowners and roofing professionals end up overdriving the screws.
This can damage the roofing panel and lead to other problems that may need to be addressed. For instance, overdriving the screws creates excess torque that could break the washer or spin it to the side, creating a path for water to sip through the roof.
Under Driven Screws
At times, the roofing company may not use enough torque on the screw, resulting in the rubber washer not being properly sealed against the panel. As a result, no gasket seal is formed as the rubber part of the screw is never compressed.
Screws Driven at the Wrong Angle
At times, the screws can be driven down at the wrong angle, resulting in an improper seal. This keeps the washer from sitting flat on the roofing panel. As a result, only a portion of the screw is sealed, causing leaks to develop.
Screws Missing the Metal Strut
In this case, thereís nothing to seal against.
Leaks resulting from screws missing the metal strut are difficult to find because youíll only be able to see the screw but wonít know that it failed to seal.
2. Missing Sealants
Sealants are usually installed at the same time as your metal roof.
The problem is, sealants donít last as long as your roof and need to be replaced from time to time. Ensuring the sealants are tight in place should be a part of your maintenance routine, particularly around these areas.
- Metal ridge caps
- Pitch pans
- Counter flashings
- Roof transitions
If possible, have a roof professional inspect the sealants.
If they need to be replaced, make sure youíre only using sealants designed for metal roofing. Typical silicon caulking isnít ideal for metal roofs as it may not survive the constant expanding and contraction associated with metals.
3. Surface Rust
Rusting is a common phenomenon in metal roofs.
This electrochemical process occurs when metal is exposed to elements, such as rain and moisture. Three elements responsible for rusting are iron, water, and oxygen. If not addressed, rust can cause metal leaks.
Fortunately, rust doesnít immediately equate to leaks.
If you notice surface rust on your metal roof, address it immediately. If not removed on time, rust causes the coating to peel. Eventually, it will corrode the metal roofing, causing holes responsible for leaking. One way to prevent rust from spreading is to use a rust inhibitor.
Rust inhibitor wonít give your metal roof anti-rusting properties, but it will buy you enough time to do the necessary repairs.
4. Physical Damage
Physical damages are an obvious cause of roof leaks.
Physical damages could result from the physical movements of homeowners or professionals when installing HVAC systems and rooftop transmission devices. Physical damage could also result from wear and tear from many years of usage.
HVAC systems, in particular, can cause significant damage to your metal roof. For instance, if a heavy HVAC unit is dragged across a metal roof, it can cause dents, scraps, punctures, and deflections to develop on the roof.
Water can eventually pool in the area of deflection or leak through the punctures, causing rust. Always inspect your roof regularly, particularly after having work done, to ensure no dents, deflections, or holes are left that can cause roof leaks.
5. Stack Flashings
Stack flashings are another area on the roof highly vulnerable to leaks.
For starters, stack flashings refer to the flashings around pipes protruding the metal roofs. Plumbing pipes, HVAC vents, and air vents come through the metal roofs.
Most metal roofs use stack flashings in which rubber or rubberized material is placed on the roof surface around the pipes and vents. This material creates a strong barrier against water seepage. If not properly installed, the flashings can loosen with time, causing leakage.
6. Incompatible Materials
Metal roofing systems require the use of specific materials to prevent oxidation and corrosion. For instance, painting can help prevent corrosion.
But for it to effectively prevent oxidation and rusting, the use of the right paint is recommended. Ideally, youíll want to paint it with a primer that contains at least 80% zinc, as zinc works great at preventing rust.
Itís also advisable to use high-quality metal roofing panels. Having a high amount of zinc in your panels is essential for protecting the cut edges.
Youíll also want to use the right materials to install flashing in vulnerable areas, such as vents, skylights, etc. The wrong sealants and metals will do more harm than good for the integrity of your roof.
As for the sealants, make sure to use acrylic or urethane coating. These options work great at sealing the space where leaks happen and preventing rust. Elastomeric coating is also recommended as an excellent option for preventing rust.
7. Cracked Chimney
Chimneys are vulnerable to cracking. The cause of cracking can be from failed flashing or holes in the chimney roof, especially during harsh weather.
In most cases, lousy flashing is the culprit.
Two types of flashing are used for roofing around a chimney: a step flashing and counter flashing. The step, also known as base flashing, is expertly woven into the roofing material to protect the seams between the roof and the chimney.
Counter flashing, on the other hand, is usually placed over the step flashing parallel to the chimney. When you have a metal roof, the chimney flashing can be one of the toughest parts of roofing. Unfortunately, not all roofing companies have the experience or know-how to flash in chimneys properly.
If your roof leak results from chimney flashing problems, seek the services of a professional experienced in flashing metal roof chimneys.
8. Dirty and Unmaintained Gutter
Trees beside your house can have a lot of benefits. For one, they provide better air circulation and shade from sunlight.
But trees may not be beneficial to your roof.
Leaves, fruits, and tree trunks may fall into your roof and eventually fall into your gutter. These debris may clog your gutter, causing water to overflow and leak into your house.
Not only that, leaves and trunks may cause the gutters to rusk quickly. And with time, as the rust worsens, youíll have no option but to replace the gutters if you wish to have peaceful days during the rainy season.
9. Mechanical Wear and Tear
Rain, wind, and heat from the sun can cause mechanical wear and tear on metal roofs.
Over time, the roof flashings become loose and develop gaps that rainwater may sip into, causing roof leaks. Once these areas begin to let water in, rust may also develop, worsening the roof leaks over time. Routine roof maintenance can help spot roof vulnerabilities that may lead to leakage.
10. Seams and Overlaps
Watch out for seams and areas where panels overlap on your metal roof. Itís critical for these joints to be tightly sealed when your roof is first installed.
Seams where two metal sheets overlap often leak because of a process called capillary draw. Capillary draw happens when water travels uphill between two closely connected pieces of metals. The problem can be fixed using a sealant or butyl tape.
Hire a Professional Roofer You Can Trust
A leaking metal roof can be troublesome.
It can cost you a lot of money in structural damages and repairs. Worst of all, the mold and dampness can seriously impact your respiratory health.
Having a roofing contractor to check on and repair your roof is critical. If youíre dealing with a leaking metal roof, contact a trusted roofing contractor in Denver. We offer free residential inspection and consultation to help you determine your next step. We also provide repair services, such as seam and fastener replacements to restore your metal roof to its former glory.
Contact us today for a free consultation.