7 Common Causes of Commercial Roof Leaks & How to Fix Them Fast
25, Jul 2025
A roof leak in a commercial building isn’t just a small problem—it can really affect your business. It can stop work, damage products, and lead to costly repairs. If left untreated, even a small leak can cause bigger issues like mold, electrical dangers, and major damage. And to prevent roof leaks from getting worse, business owners can take action by knowing what causes them. This guide will cover the 7 common causes of roof leaks and how to fix them.
1. Poor Installation and Bad Workmanship Can Cause a Roof Leak
Commonly, the reason for a roof leak is simply poor installation. Water can get in if roofers hurry the job, don't seal gaps properly, or don't secure roofing materials securely. When the water gets in, you'll have to deal with broken ceilings, expensive repairs, and a lot of stress.
What Can You Do?
First, hire people who are good at what they do. Make sure the contractors are licensed, have a lot of expertise, and are known for good roof repairs. Regular inspections will help you find problems early on, before they require an emergency roof repair. If you see a leak in your roof, you need to act quickly to stop more damage.Did You Know?
The NRCA says that one of the main reasons roofs fail too soon is that they were not installed properly. If you don't follow the rules when installing, you could damage your roof for good and make it last less time, which will make repairs more expensive in the long run2. Aging and Weather Damage Often Lead to Roof Leaks
Over time, commercial roofs wear out, especially in Vancouver, where the weather changes all the time. Heavy rain, snow, temperature changes, and constant exposure to UV radiation can damage roofing materials. You might not even realize it, but cracks can happen and cause a roof leak.
What You Can Do to Prevent It:
- Schedule regular roof inspections, particularly following severe weather events or storms.
- Apply waterproof coatings to protect it from moisture.
- Don’t delay replacing cracked or aging materials, as this can lead to serious roof leak repair issues.
Quick Tip:
The National Research Council of Canada points out that UV rays can degrade roofing membranes over time, making your roof more susceptible to leaks and reducing its lifespan.Want to know what causes a roof to wear out too soon? Check out this helpful guide: 7 Important Factors That Cause Commercial Roofing to Wear Out Too Soon.
3. Ponding Water & Poor Drainage Can Make a Roof Leak Worse
Flat roofs are more likely to have water pool on them, which means that the water doesn't drain away correctly. This makes the roof heavier and steadily degrades the material, which will eventually cause a roof leak.
How to Fix It:
- Keep drains, gutters, and downspouts clean and free of debris.
- Consider adding tapered insulation or installing additional drainage systems to help water flow off the roof more easily.
Good to Know:
The Canadian Roofing Contractors Association (CRCA) advises that commercial roofs to have at least a 2% slope in order to prevent ponding and avoid roof leaks or expensive repairs later.4. Worn-Out Flashing & Sealants Can Lead to a Roof Leak
Flashing is the metal or waterproof material that goes around vents, chimneys, and skylights. Its job is to keep water out of the roof. Flashing can, however, still fracture, corrode, or come loose over time, causing holes that let water in and cause a roof leak.
How to Fix It:
- Check your flashing regularly for cracks, rust, or gaps that could be harmful.
- Reapply sealant to weak spots to make them less likely to leak.
- Replace worn-out flashing with more durable, weather-resistant materials.
5. HVAC and Rooftop Equipment Can Cause a Roof Leak
Commercial buildings often have HVAC systems, vents, and other equipment on their roofs. Water can seep in and result in a roof leak if these things are not properly sealed.
How to Prevent and Fix These Issues:
- Ensure all rooftop equipment is installed and sealed properly using quality flashing.
- Look for gaps or cracks around the equipment and reseal them to stop leaks.
- Schedule routine inspections and maintenance by roofing professionals who specialize in roof leak repair.
JD Supra says that not having enough flashing around equipment can potentially let water in, which can lead to expensive repairs.
6. Small Punctures Can Lead to a Big Roof Leak
Roof materials like EPDM, TPO, or PVC are strong, but they can still be damaged. Small holes can form from things like falling branches, heavy foot traffic, or severe weather, letting water seep in and cause a roof leak.
What You Can Do:
- Limit foot traffic on the roof to prevent damage.
- Put protective walkway pads where people need to walk.
- If you see any little tears or holes, don't wait; get them fixed as soon as possible to prevent bigger issues.
7. When Gutters Get Clogged, Your Roof Can Pay the Price
If your gutters are clogged, water can back up and get under the roof, which can lead to a leak. This can cause harm that is hard to see until it's too late.
What You Must Do:
- Clean your gutters regularly, especially after storms or during the fall.
- Install gutter guards.
- Check your downspouts.
Don't forget that a small clog today could mean costly roof repairs tomorrow.
When to Call for Emergency Roof Repairs
Having a roof leak in a commercial building can quickly become a big problem. They can break down your business, cost a lot to fix, and even put people in danger. Taking precautions can save you from having to deal with big problems later on, which is a good thing.
Signs You Need Emergency Roof Repairs:
- A sudden, heavy roof leak that won’t stop.
- Water stains on ceilings or walls that spread quickly.
- Mold or mildew is showing up inside the building.
- Visible roof damage after a storm.
What You Need to Do Immediately:
- Call a roofing expert who specializes in roof leak repair.
- Cover the leak with a tarp or plastic sheet temporarily to minimize further damage.
- Schedule a comprehensive inspection to find any hidden damage and see if the roof needs to be fixed right now.
Final Thoughts: How to Prevent Commercial Roof Leaks
Roof leaks in commercial buildings can cause serious financial stress if not fixed quickly. Water damage can cause costly repairs, interfere with company operations, and pose safety risks. The good news is that with the right precautions, you can avoid these problems down the road.
How to Protect Your Property:
- Schedule regular roof inspections to catch small issues before they become big problems.
- Use high-quality materials and work with professional roofing repair services.
- Take care of drainage, flashing, and membrane issues to prevent leaks.
- Act quickly if you spot a roof leak to avoid costly emergency roof repairs.
Staying proactive and addressing roof leak issues quickly can help you avoid costly repairs, minimize business disruption, and extend the lifespan of your roof
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