Flat Roof Repair Services | Roofing Leaks and Moisture Intrusions
Stop Roof Leaks Fast. Protect Your Property. Guaranteed Solutions.
Reliable flat roof repair services specializing in leak detection and moisture intrusion prevention. Extend your roof’s lifespan with expert solutions you can trust. Stop leaks before they spread! Our flat roof repair experts quickly identify and fix roofing leaks and moisture intrusions, ensuring long-lasting protection.
Stop Leaks Before They Worsen
A tiny leak today becomes a water-soaked nightmare tomorrow.
We've seen it hundreds of times. A client notices a small damp spot on their ceiling and figures they'll deal with it "next month." Fast forward six weeks and they're calling us because their insulation is saturated, drywall is crumbling, and they've got mold creeping up the walls.
The math on this is pretty straightforward. A minor flat roof repair might run you a few hundred dollars. Wait too long and you're looking at thousands in structural damage, ruined inventory (if it's a commercial property), and lost business or living space while repairs drag on.
Here's what really gets expensive: compromised insulation. Once water soaks through, it loses its R-value and your heating bills climb. We had a client in Whitby whose energy costs jumped 30% over one winter because a small leak they ignored turned their attic insulation into a soggy mess.
And those DIY sealants you see at the hardware store? They're a temporary band-aid at best. Most homeowners grab a tube of something, slap it on the problem area, and call it fixed. Three months later (usually right after a heavy rainstorm) the leak's back—and often worse because water found a new path around that patch.
Professional repair isn't just about stopping the leak. It's about protecting your roof warranty. Most manufacturers will void coverage if you've attempted amateur fixes or if damage spreads because you didn't address it promptly. We've had customers lose out on $15,000+ warranty claims because they waited too long or used the wrong materials.
Clear Signs You Need Expert Flat Roofing Repair Services
Your roof is basically screaming at you when something's wrong. You just need to know what to listen for.
Persistent ceiling stains or peeling paint – This one's obvious, but people ignore it more than you'd think. If you've got brown or yellow watermarks that keep coming back after you paint over them, water is actively getting in.
Standing water that doesn't drain after rainfall – Flat roofs should drain within 48 hours max. If you've got puddles hanging around for days, your drainage system isn't doing its job and you're inviting membrane damage.
Bubbling or cracked roof membrane – Walk your roof (carefully) and look for blisters in the surface or visible cracks. These are weak spots where water will eventually punch through.
Damp insulation or visible drips indoors – Once you see water inside, the damage has already started. Check your attic or top floor for any signs of moisture.
Musty odours or mold spots near walls or ceilings – Your nose knows. That basement smell on your top floor? That's mold growth from trapped moisture.
We did a job last fall where the property owner swore they didn't have any leaks. No visible water, no stains. But they mentioned a "weird smell" in one of their upstairs rooms. Turned out they had a slow leak that had been saturating insulation for months. The mold remediation alone cost more than the roof repair would have if they'd caught it early.
What Really Causes Leaks on a Flat Roof
Leaks don't just happen. There's always a reason, and it's not always where you think.
The obvious culprit is separated seams or punctures in your membrane—whether it's EPDM, TPO, or modified bitumen. These roofing systems rely on perfectly sealed seams. When those seams fail (from age, poor installation, or physical damage), water finds its way in.
Flashing is another common failure point. Every penetration in your roof—vents, drains, skylights, HVAC units—needs properly installed flashing to keep water out. We see failing flashing on probably 40% of the leak calls we respond to. The original installer either used cheap materials, didn't seal it correctly, or the flashing has just aged out.
Then there's ponding water. Your flat roof should have a slight slope (typically 1/4 inch per foot minimum) to move water toward drains. If the slope is wrong or drains get clogged, water sits. And sits. And eventually works its way through even a healthy membrane. According to the National Roofing Contractors Association, ponding water can reduce membrane lifespan by up to 50%.
Aged or brittle coatings are sneaky. UV exposure breaks down protective coatings over time. Once the coating fails, your membrane is exposed to accelerated wear. It cracks, loses flexibility, and starts letting water penetrate.
Temperature swings cause expansion and contraction. In Ontario, we see huge temperature variations—scorching summers and freezing winters. Materials expand in heat and contract in cold. Do that cycle enough times and you get stress fractures, separation at seams, and membrane shrinkage that pulls away from edges and penetrations.
Our Proven Repair Process
We don't just patch and pray. There's an actual system to this.
Comprehensive Leak Detection – First step is finding where water is actually getting in, which isn't always where you see it inside. Water travels. We use visual inspection plus moisture detection tools to trace leaks back to their source. Skip this step and you're fixing symptoms, not causes.
Surface Preparation – You can't seal a wet or dirty surface. We clean the area thoroughly and make sure it's completely dry. Most DIY repairs fail because people skip this part—they're in a hurry and slap sealant on a damp, dirty roof. It doesn't stick. It doesn't last.
Membrane Repair or Replacement – Now we cut out damaged sections and patch or replace them with high-performance materials that match your existing system. This isn't a paint-on fix. We're talking proper membrane installation with heat welding or adhesive depending on your roof type.
Flashing Reinforcement – Every penetration gets checked and reinforced. We secure any loose flashing, replace failed sections, and make sure every drain, vent, and seam is properly sealed.
Protective Coating Application – Once the structural repair is done, we apply UV-resistant coating to extend the life of the repair and protect against future damage. Think of it as sunscreen for your roof.
Quality Check & Documentation – Before we leave, we verify everything is watertight and provide you with a detailed report of what we did. If there are other areas of concern we spotted during the repair, we'll note those too so you can plan ahead.
Had a commercial client in Oshawa last spring whose warehouse was leaking in three spots. Turned out the leaks were coming from failed seams around their HVAC units. We didn't just patch the obvious spots—we reinforced all the penetrations and found two more weak points that would have failed within six months. That's the difference between a patch job and a professional repair.
Why Choose C.D. Roofing & Construction Ltd.
Look, we're not going to tell you we're the only roofing company in Durham Region. But we are going to tell you what sets us apart.
We're certified and insured flat roofing specialists. That's not just a line—we have the training and credentials to work on commercial and residential flat roof systems. Not every roofer does.
We've been doing this for over two decades. Since 2003, we've repaired and replaced thousands of roofs across Durham Region. That experience means we've seen just about every roof problem that exists and know how to fix it right the first time.
Transparent pricing matters. We're not the guys who give you a vague estimate then tack on mysterious charges later. You'll know exactly what the repair costs and what's included before we start.
We stand behind our work with real warranties—both on materials and our workmanship. If something fails because of how we installed it, we fix it. Period.
Most of our business comes from repeat clients and referrals. That should tell you something. People don't recommend roofing companies they're unhappy with, and they don't come back for their next project if you did a bad job the first time.
We're not the cheapest option in town. We're the option that saves you money in the long run because we do it right and it lasts.
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Protect Your Investment with Routine Maintenance
You wouldn't skip oil changes on your car for five years and expect it to run perfectly. Same logic applies to your roof.
Semi-annual inspections catch problems before they become expensive emergencies. We recommend spring and fall check-ups—after winter damage and before winter arrives.
Clean gutters, drains, and roof surface sound boring, but clogged drains cause ponding water, which causes leaks. Fifteen minutes of clearing debris twice a year prevents thousands in water damage.
Check seams, flashings, and penetrations during those inspections. A loose flashing or separating seam is easy to fix when you catch it early. Wait until it's leaking and the repair gets more complicated and costly.
Reseal worn areas before they fail. We can often recoat or touch up problem areas during maintenance visits—stopping leaks before they start.
Document everything for warranty support. Keep records of all maintenance and repairs. If you ever need to make a warranty claim, that documentation is gold.
One of our Ajax clients has been on a maintenance plan with us for eight years. Their flat roof is 18 years old and still going strong because we catch small issues during regular visits. Compare that to their neighbour who ignored maintenance and had to do a full replacement at year 15. The math speaks for itself.
Flat Roof Leak Repair Costs
Nobody wants to talk about money, but everyone wants to know what they're looking at.
The truth is every roof repair is different, so we can't give you an exact number without seeing your specific situation. But here's what affects the price:
Size and complexity of the damaged area – A small puncture repair costs less than replacing an entire section of membrane. Simple as that.
Type and age of roofing system – Some materials are more expensive to work with. An older roof might need more extensive prep work or have hidden damage.
Accessibility and roof height – A single-story garage is easier (and cheaper) to work on than a three-story commercial building. Equipment, safety measures, and time all factor in.
Optional coatings or full-section replacement – Sometimes it makes sense to coat a larger area or replace an entire section rather than just patching. We'll tell you if that's the case.
Warranty or maintenance package – Extended warranties and ongoing maintenance plans add value but come with additional cost upfront.
For perspective, a basic leak repair might run anywhere from $500 to $2,000 depending on the factors above. More extensive repairs can run higher. A full roof replacement (if that's what's actually needed) is obviously more substantial.
We've turned away jobs where a homeowner wanted us to patch a roof that was beyond repair. Sure, we could have taken their money for a temporary fix, but it wouldn't have lasted. Sometimes the honest answer is "you need a new roof," even though that's not what people want to hear.
Frequently Asked Questions
Don't Wait for the Next Storm—Stop the Leak Today
Every day you wait is another day that leak is spreading, water is soaking in, and damage is compounding.
Protect your building, prevent expensive structural repairs, and restore peace of mind with expert flat roof leak repair from C.D. Roofing & Construction Ltd. We've spent over 20 years fixing roofs across Durham Region, and we're really good at it.
Need immediate help? Call now: (905) 430-7911