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Flat Roofing Edmonton | Is it OK to Put New Shingles Over Old?

Brown’s Roofing Edmonton Educates Homeowners About Roof Services

When it comes to protecting your home, your residential flat roofing in Edmonton plays one of the most important roles—and that’s especially true here in Alberta, where weather turns on a dime. Homeowners often ask whether they can install a fresh layer of shingles over an existing layer to save money and avoid a complete tear-off. While that might sound convenient, it’s not always safe, legal, or wise, particularly for homes with low-slope or flat roof areas. Before making a decision that impacts your home’s long-term durability, it’s important to understand how roofing systems work, what Alberta building codes allow, and what roofing contractors look for during an inspection. Brown’s Roofing in Edmonton has seen every roofing situation imaginable, and this guide breaks down everything homeowners should know before adding new material over old.

Understanding Flat Roofing and Edmonton’s Climate Challenges

Not all roofs are built the same. Many homeowners believe any roof with a slight angle is suitable for shingles, but low-slope and flat roofs require their own system. A roof is considered “flat” when its pitch is too low to naturally shed water the way a regular sloped roof does. That means drainage becomes the biggest concern. Edmonton’s climate pushes flat roofs to the limit. We regularly experience major freeze–thaw cycles, heavy snow loads, drifting snow, sudden warm-ups, ice dams, and rapid temperature swings. All these factors make shingles a poor choice for flat surfaces because they rely on gravity. They must overlap tightly so water can drain downward. On a flat surface, water will sit rather than flow, leading to leaks, rot, mold, and material failure. For this reason, flat roofing in Edmonton requires specially designed roofing membranes such as SBS torch-on, TPO, EPDM, or modified bitumen—systems built to handle standing water, expansion, and contraction.

Can You Legally Put New Shingles Over Old Ones in Edmonton?

Technically, Alberta’s building code may allow a second layer of shingles under certain conditions, but there are strict rules. The existing roofing material must be lying flat with no curling, buckling, cracking, or missing sections. The sheathing underneath must be structurally sound. There must be no moisture damage, rot, or mold. The current roof must be properly ventilated to prevent ice-dam formation and trapped humidity. Even if all those conditions are met on a sloped roof, flat roofs are another story entirely. For homes with any low-slope or flat areas, overlays generally do not meet code because the risk of leaks is significantly higher. Insurance providers may refuse coverage if an overlay is installed in an unsuitable area, and many manufacturers will void warranties when installed over old layers. Homeowners sometimes choose an overlay to save money upfront, but most roofing professionals—including Brown’s Roofing—strongly recommend against it. A complete tear-off allows the contractor to inspect the wood decking, ventilation, moisture barriers, and the overall structural condition of the roof. Without tearing off old material, underlying problems will be hidden and can worsen year after year, making timely flat roof replacement essential.

Why Installing New Shingles Over Old Ones Causes Expensive Problems

Layering shingles may appear harmless, but it comes with a long list of potential issues. First, weight matters. Asphalt shingles already add considerable weight to a roof. Adding a second layer increases stress on rafters, sheathing, and overall structural integrity. This is especially concerning during Edmonton’s heavy snow seasons, where additional weight can push older homes beyond safe limits. Second, moisture becomes trapped more easily between old and new material. If the original shingles have dips, soft spots, or previous leak damage, the overlay seals that moisture inside the roof system. Over time, that moisture spreads, causing mold growth, wood rot, and deterioration that stays hidden until major damage becomes visible inside the home, highlighting the importance of regular roof inspections. Third, overlays reduce the life expectancy of the new shingles. Heat from the sun transfers less efficiently, the material ages faster, and curling or cracking occurs sooner. Warranties are often voided, and future repairs become far more expensive. And finally, when the time comes to replace the roof properly, removing two layers instead of one increases labour, disposal costs, and project time. A temporary shortcut now becomes a costly mistake later.

Proper Replacement Options for Flat and Low-Slope Roofs

If a home has flat or low-slope sections, shingles should never be used—and overlays are absolutely off the table. Instead, flat roofs require a completely different approach. Torch-on roofing is one of the most common systems for flat roofing in Edmonton, known for strength, water resistance, and durability through freeze–thaw cycles. Another strong choice is EPDM, a rubber membrane that handles movement extremely well and performs in extreme cold. TPO is another modern option, offering heat-welded seams and energy efficiency. Modified bitumen and multi-layer membrane systems are excellent for long-term weather protection. Brown’s Roofing takes the time to inspect the structure, identify moisture problems, and choose the correct membrane for the home. Unlike shingle systems, flat roofing membranes are designed to resist ponding water, seal tightly, and remain flexible in harsh conditions. With proper installation, these systems offer long service life and reduced maintenance needs.

How Brown’s Roofing Ensures a Safe, Code-Compliant Roof Replacement

When homeowners call Brown’s Roofing specialists, the team begins with a comprehensive inspection that includes photos of every section of the roof. This transparency shows homeowners exactly what is happening beneath the materials or membrane. If a full tear-off is required, the team carefully removes all old material, checks for soft spots, rot, or mold, and inspects the sheathing for strength. Ventilation upgrades are made when needed to prevent ice dams and humidity issues. High-quality underlayments, ice-and-water barriers, and manufacturer-approved materials are installed to ensure the system performs at its best. Brown’s Roofing also offers strong workmanship warranties and provides clear, detailed quotes with no-pressure sales. Homeowners know exactly what they are getting, and every stage of the roofing project is documented with before-and-after photos. This level of professionalism gives customers peace of mind knowing their home is protected.

Roofing Contractor Frequently Asked Questions

Can I ever install shingles on a flat roof?

No, this material is not suitable for flat or low-slope areas because they cannot properly shed water.

Is installing new shingles over old ones cheaper?

Upfront, yes—but the long-term damage often costs far more to fix.

Will an overlay void my warranty?

In many cases, yes. Manufacturers often require a full tear-off roof installation.

How often should flat roofs be inspected?

At least once a year and after major weather events.

Can Brown’s Roofing work in winter?

Yes, their roofers installs and repairs roofs year-round, even in freezing conditions.

Roof Repair and Replacements in Edmonton

While it may seem tempting to install new materials over old ones, especially to save money or avoid the mess of a tear-off, the risks far outweigh the benefits. For homes with flat or low-slope sections, overlays are never recommended and often not allowed. A proper, code-compliant replacement provides long-lasting protection, better performance, and peace of mind. With expert inspections, transparent quotes, and high-quality workmanship, Brown’s Roofing can provide your quality roofing needs for Edmonton’s demanding climate. When you want a safe, durable residential roofing solution, reach out to the team that specializes in flat roofing in Edmonton and surrounding areas and puts homeowners first.