Your commercial roof is easy to ignore. It’s up there doing its job day after day. You probably don’t think about it until something goes wrong.
And when things go wrong with a commercial roof, they go really wrong. We’re talking thousands in damage, business interruptions, and emergency calls to a Commercial Roofing Company Denver at 2 AM because water’s pouring into your warehouse.
The good news? Most commercial roofing problems don’t just appear overnight. They build up over time with warning signs you can catch early if you know what to look for.
Let’s walk through the most common issues that plague commercial roofs and what causes them.
What You'll Discover:
Ponding Water (The Silent Killer)
Walk onto most flat commercial roofs after a rainstorm, and you’ll see it. Pools of water sitting there, not draining.
A little standing water for 24-48 hours after heavy rain? That’s normal. Water that sits for days or never fully drains? That’s ponding, and it’s a problem.
Why it happens:
Poor drainage design is the main culprit. Your roof needs slight slopes (even “flat” roofs aren’t actually flat) to guide water toward drains. When the slope is inadequate or drains are too few, water collects.
Roof sagging makes it worse. Over time, decking can sag between supports, creating low spots where water pools. HVAC units or other rooftop equipment can also create dips and valleys.
Why it matters:
Standing water accelerates roof deterioration. It works its way into seams and cracks. It degrades roofing membranes. In winter, it freezes and expands, creating more damage.
Ponding also adds weight. Water is heavy. Enough of it can stress your roof structure. And it’s a breeding ground for mosquitos, algae, and vegetation.
If you’ve got water sitting on your roof for more than 48 hours regularly, you need to address it. Add drains, improve slope, or reinforce sagging areas before it turns into a bigger problem.
Membrane Damage and Punctures
Commercial roofs typically use membrane systems like TPO, EPDM, PVC, or modified bitumen. These are tough, but they’re not indestructible.
Punctures, tears, and holes happen more often than you’d think.
Common causes:
Foot traffic is a big one. Workers servicing HVAC units, installing satellite dishes, or doing maintenance walk across your roof. Dropped tools, sharp objects, or just repeated wear create damage.
Hail and debris also puncture membranes. A severe hailstorm can pockmark a roof. Falling tree branches during storms tear through material.
Poor installation causes problems, too. Membranes not properly adhered or seams not correctly welded fail prematurely.
Warning signs:
You might not see punctures from the ground. But inside, you’ll notice water stains, leaks during rain, or damp insulation.
Regular roof inspections catch these early. Small punctures can be patched. Large tears might need section replacement. Ignore them, and you’re looking at water damage to your building’s interior, insulation, and structural components.
Blow-Offs and Lifting (Wind Damage)
Commercial roofs are big and flat. That makes them vulnerable to wind.
Strong winds can lift sections of roofing membrane, peel back edges, or even tear off entire sections in extreme weather.
Why it happens:
Improper installation is the usual suspect. If the membrane isn’t correctly fastened or adhered to the substrate, wind gets underneath and lifts it like a sail.
Age and deterioration matter too. Adhesives weaken over time. Fasteners work loose. What held firm for 15 years might not hold anymore.
Building location plays a role. Roofs on tall buildings, roofs exposed to prevailing winds, or roofs in coastal areas face more wind stress.
The damage:
Once wind gets under your membrane, it can propagate quickly. A small lifted section becomes a bigger one. Eventually, you’ve got flapping membrane, exposed insulation, and water intrusion.
After any major windstorm, walk your roof or have someone inspect it. Look for lifted edges, loose material, or damaged flashing. Catch it early and repairs are straightforward. Wait and you might be replacing entire sections.
Flashing Failures
Flashing is the material that seals transitions – where your roof meets walls, around penetrations like vents and pipes, at edges and perimeters.
It’s also one of the most common leak sources in commercial buildings.
Why flashing fails:
Improper installation tops the list. Flashing needs to be correctly overlapped, sealed, and fastened. Cut corners here, and you get leaks.
Thermal movement causes problems. Buildings expand and contract with temperature changes. If flashing isn’t designed to accommodate movement, it cracks or separates from joints.
Age and weathering break down sealants. UV exposure degrades caulks and mastics. What sealed perfectly 10 years ago might be cracked and failing now.
Where to look:
Check flashing around:
- HVAC units and rooftop equipment
- Pipes and vents penetrating the roof
- Parapet walls and roof edges
- Expansion joints
- Skylights and hatches
Leaks from failed flashing often show up inside the building, far from the actual roof leak point. Water travels along beams and decking before dripping down.
Annual inspections should specifically check all flashing. Re-seal as needed. Replace deteriorated sections before they leak.
Poor Drainage and Clogged Drains
We mentioned ponding already, but drainage deserves its own section because it’s so critical and so commonly neglected.
Your commercial roof has drains, scuppers, or gutters to move water off. When those get clogged, water backs up.
What clogs drains:
Leaves, dirt, and debris wash into drains and block them. Rooftop HVAC units shed dust and particles. Trees near buildings drop leaves and branches. Even roofing granules from older roofs accumulate.
In some cases, drain strainers get knocked off or damaged, letting debris deep into drain pipes where it’s harder to clear.
The consequences:
Clogged drains mean water has nowhere to go. It ponds, it backs up, it eventually finds its way inside through any available opening.
Backed-up water can overflow into your building through roof hatches, around penetrations, or through parapet wall seams.
The fix:
Clean your drains at least twice a year – spring and fall. More often if you have trees nearby or heavy debris accumulation.
Install drain strainers if you don’t have them. They’re cheap insurance against costly clogs.
Consider leaf guards or screens over drains in areas with heavy tree coverage.
Shrinkage and Cracking
Some roofing materials shrink over time. EPDM rubber roofing is particularly prone to this.
As the membrane shrinks, it pulls away from flashing, opens up seams, and creates stress at fastening points.
Why it happens:
UV exposure and temperature cycling cause material breakdown and shrinkage. Decades of hot summers and cold winters take a toll.
Improper installation can accelerate it. If membrane wasn’t properly relaxed before installation or was installed in very cold weather, it might shrink more as it settles.
What you’ll see:
Pulled-back membrane at roof edges and flashing. Open seams between membrane sections. Stress at fastener points. In severe cases, actual cracks in the membrane.
Addressing it:
Minor shrinkage can sometimes be addressed by adding termination bars or re-securing edges. Major shrinkage often means you need a new roof.
This is why proper installation matters so much. A well-installed membrane lasts 20+ years. A poorly installed one might show problems in 5-10 years.
Blistering and Bubbling
Walk a commercial roof and you might see raised bubbles or blisters under the membrane. They range from small bumps to large sections.
The cause:
Blisters form when moisture or air gets trapped between roofing layers or between membrane and substrate. As temperatures rise, that trapped moisture vaporizes and expands, creating a blister.
Poor installation is often responsible. If moisture was present during installation or if layers weren’t properly bonded, blisters form.
Why they’re a problem:
Small blisters might not leak immediately, but they’re weak points. They’re more susceptible to puncture and damage. Large blisters can rupture, exposing underlayment and insulation.
Blisters also indicate moisture in your roofing system, which degrades insulation and reduces energy efficiency.
What to do:
Small blisters that aren’t leaking can sometimes be left alone and monitored. Large ones or those that have ruptured need repair – typically cutting out the affected section and patching.
Preventing blisters means ensuring proper installation with dry conditions and correct adhesive application.
Roof Penetration Leaks
Every hole in your roof is a potential leak point. Commercial buildings are full of them:
- HVAC units and their associated pipes
- Plumbing vents
- Electrical conduits
- Gas lines
- Satellite dishes and antennas
Why they leak:
Flashing around penetrations fails (we covered that). Sealants deteriorate from UV exposure and temperature cycling. Fasteners work loose.
Sometimes new equipment gets added, and penetrations aren’t properly flashed. Someone bolts something to your roof without waterproofing it correctly.
Prevention:
Any time you add equipment or penetrations to your roof, ensure they’re properly flashed and sealed. Don’t let maintenance crews just drill holes and slap some caulk around them.
Inspect penetrations annually. Re-seal as needed. Replace damaged flashing.
When possible, minimize roof penetrations. Sometimes you can run multiple pipes or conduits through a single penetration boot rather than creating multiple holes.
UV and Weather Degradation
Commercial roofs face constant assault from the elements. Sun, rain, snow, wind, temperature swings – it all adds up over decades.
What happens:
UV radiation breaks down roofing materials. Membranes become brittle. Sealants crack. Colors fade (which actually indicates material breakdown, not just aesthetics).
Freeze-thaw cycles stress materials. Water gets into tiny cracks, freezes and expands, making cracks bigger. Repeat thousands of times over years.
Chemical exposure from air pollution or nearby industrial operations can accelerate deterioration in some environments.
Managing it:
You can’t prevent weather, but you can slow degradation. Reflective coatings reduce UV damage and thermal stress. Regular maintenance catches small problems before they become big ones.
Proper drainage prevents standing water that accelerates breakdown. Keeping the roof clean prevents debris from holding moisture against the membrane.
Eventually, every roof reaches end of life from weathering. But good maintenance stretches 15-year roofs into 20-year roofs and 20-year roofs into 25-year roofs.
Poor Installation (The Root Cause)
Notice a pattern in many of these problems? Installation quality matters enormously.
A properly installed commercial roof handles stress better, drains correctly, and lasts longer. A poorly installed roof shows problems within a few years.
Common installation mistakes:
Inadequate substrate preparation. The roof deck needs to be clean, dry, and properly prepared before membrane goes down.
Incorrect fastening. Too few fasteners or improperly placed ones lead to blow-offs. Too many or poorly placed ones create leak points.
Poor seam welding or adhesive application. Seams are critical. Rushed or improper seaming creates immediate weak points.
Ignoring manufacturer specifications. Every roofing system has specific installation requirements. Cutting corners or deviating from specs voids warranties and creates problems.
Protecting yourself:
Hire experienced commercial roofing contractors. Check references and past work. Verify they’re certified installers for the specific roofing system you’re using.
Get warranties in writing – both manufacturer material warranties and contractor labor warranties.
Have someone knowledgeable inspect the work before final payment. Catch installation errors immediately, not five years later.
Lack of Maintenance (The Multiplier)
Here’s the thing about commercial roofs: minor problems become major problems when ignored.
A small puncture that could be patched for $200 becomes a $5,000 section replacement after water damages insulation and decking.
A clogged drain that needs 10 minutes of cleaning becomes a collapsed roof section from water weight.
What maintenance looks like:
Twice-yearly inspections (spring and fall minimum). More if you’re in harsh climates or have problematic trees nearby.
Cleaning drains and gutters. Removing debris. Trimming overhanging branches.
Minor repairs as needed – re-sealing, patching small punctures, securing loose flashing.
Documentation. Keep records of inspections, repairs, and conditions. This helps you track deterioration and plan for eventual replacement.
The ROI:
Maintenance costs money. But it’s a fraction of what major repairs or premature replacement costs.
A $500-$1,000 annual inspection and maintenance visit can prevent $10,000-$50,000 emergency repairs. The math is pretty simple.
When to Replace vs. Repair
Not every problem needs a full roof replacement. But at some point, repairs stop making financial sense.
Consider replacement when:
- You’re doing major repairs every year or two. You’re throwing good money after bad.
- Your roof is past its expected lifespan. Most commercial roofs last 15-30 years, depending on type and maintenance.
- Multiple system-wide issues exist. If you’ve got widespread ponding, deteriorated membrane, and failed flashing all at once, replacement might be cheaper than piecemeal repairs.
- Energy costs are high. New roofing systems with better insulation and reflective membranes can significantly reduce heating and cooling costs.
Stick with repairs when:
- Problems are isolated and specific. One damaged section doesn’t mean the whole roof is shot.
- The roof is relatively young and well-maintained. A 7-year-old roof with a small leak needs repair, not replacement.
- Underlying structure and insulation are sound. If problems are just membrane-level, re-covering or coating might work.
Get opinions from multiple qualified contractors. Avoid anyone who automatically recommends replacement without thoroughly assessing repair options.
Bottom Line
Commercial roofing problems rarely appear out of nowhere. They develop over time from installation issues, weather exposure, lack of maintenance, or just age.
The key is catching them early. Small problems are cheap to fix. Big problems cost serious money and disrupt your business.
Walk your roof a few times a year. Look for ponding, damage, or obvious issues. Have professional inspections annually. Budget for maintenance and repairs.
Your roof is a major investment protecting everything under it. Treat it accordingly, and it’ll last its full lifespan and then some.
