Metal Roof Retrofit with Insulated PVC Roofing Systems

Installing a Low-Slope Retrofit Roof Assembly Over an Existing Metal Roof

The journey of every retrofit installation project we undertake begins with establishing a strong and professional relationship with our client. We listen to your needs and understand that your residential or commercial roof is a significant investment in terms of finance, security, and comfort.

Next, we customize our services to match your roofing needs, support your aspirations, and address your concerns. Therefore, when you choose our team to correct performance issues related to your metal roof, rest assured of the following;

Quality Workmanship and Materials

At Watertite Roofing, quality workmanship is our signature. Our unwavering dedication to offering high-performance roof retrofits is evident in every fastener installed and every roofing seam we seal. We combine our roofing expertise with high-quality materials, including the Duro-Last and Goliath roofing systems.

The result is an economical and functional solution for Ontario building owners with low slope-metal roof assemblies in need of roof repairs or replacement.

Certified Roof Installers You Can Trust

Our team comprises certified design professionals and roof installers handpicked for their expertise in commercial and industrial roofing, skills, and commitment to excellence. Therefore, every roof installation, retrofit, repair, or replacement task is completed to code and exceeds our client’s expectations.

If you have an aging roof that needs retrofitting, contact us. Our team will assess the condition of your existing roof and determine the structural integrity of the roof assembly. We only proceed with a retrofit if the existing structure is strong enough to support a new roof assembly.

gallery

Put a New Duro-Last or Goliath Roof over the Existing Metal Roof (Retrofit)

Metal roofs are associated with lower initial installation costs and durability. However, that doesn’t factor in protection from rust, corrosion, temperature extremes, and exposure to weather elements. All these issues can compromise the structural integrity of your metal roof. If you have seen signs that time has caught up to your low-slope metal roof, contact Watertite Roofing.

You don’t have to live with the ongoing challenges of a failing roof to extend its service life. Leaks, rust spots, loose fasteners, and visible wear can quickly escalate into costly structural problems if left unchecked. For instance, moisture and water infiltration can cause mold growth within your building. Thus, addressing these warning signs early ensures your property remains protected and efficient.

Sometimes, repairing your existing roof may not be enough to prevent leaks or other forms of damage. That is where our retrofit services provide real value. Our roofing experts install a Duro-Last or Goliath retrofit roofing system directly over your existing low-slope metal roof.

During retrofitting, a new roof is installed directly on your existing roof. Custom-cut rigid insulation panels are installed in the corrugations of the existing metal roof to level it, and then the Duro-Last or Goliath roof system is installed over top. This eliminates the need for a roof removal and allows us to install a new roof assembly that is watertight, energy-efficient, and built for long-term performance. This approach saves on upfront installation costs and minimizes disruption to your business or daily operations.

Here’s why we recommend the Duro-Last or Goliath retrofit systems for low-slope metal roofs in Ontario.

No Seam and Fastener Issues

One of the most common problems with traditional metal roofs is the seams and exposed fasteners, which are vulnerable to leaks, rust, and long-term wear. With Duro-Last or Goliath systems, we can help building owners order custom-sized sheets that are custom-fabricated to your roof’s exact dimensions. This minimizes field-welded seams and creates a watertight roof surface.

At Watertite Roofing, our trusted partnerships with Duro-Last and Canadian-made Goliath ensure every roof retrofit delivers precision engineering and lasting performance.

With the Duro-Last or Goliath retrofit system, we completely encapsulate your metal roof with a monolithic, PVC flat and low-slope roof membrane, permanently sealing off all the troublesome leaking fasteners and roof seams of your old metal roof. Therefore, we can recommend the best retrofit roofing system for your building.

Cost-Effective Roofing Solution

Retrofitting a metal roof with the Duro-Last or Goliath retrofit system is one of the most cost-effective ways to upgrade your property’s roofing. Instead of a complete tear-off and replacement, we install a new Duro-Last® or Goliath roof assembly over the existing structure. This streamlined process reduces waste, saves time, and eliminates many of the costs associated with traditional roof replacement.

Lesser Material Costs

Installing the Duro-Last or Goliath roof retrofit system over the existing roof substrate eliminates the expense of tearing off and disposing of existing roof materials. This also reduces the need to purchase new insulation and vapor retardant membranes. Thus, you can make significant savings on your re-roofing budget for an existing building.

Save on Labor costs

Retrofit installations are faster and more efficient than full roof replacements. No extensive roof tear-off is necessary. This reduces the required labor hours, which lowers overall project costs while keeping your roofing upgrade on schedule. Therefore, the labor cost of retrofit systems is lower than that of a full replacement of an existing metal roof.

Minimal Disruption to Your Operations

For commercial and industrial properties, downtime can be costly. Retrofitting old and new roofs reduces noise, debris, and disruption to your activities. This allows business operations and building occupants to continue with minimal interruption. Thus, you can expect fewer productivity losses and less risk of revenue disruption compared to time-consuming roof replacement projects.

Energy-Efficient Roofing

A Duro-Last PVC membrane metal retrofit system is insulated by installing a layer of high-quality, energy-efficient insulation panels directly over the existing metal roof before the membrane is applied. This insulation fills the gaps between metal ribs and creates a flat, continuous surface that eliminates the thermal bridging common in exposed metal roofing. By reducing air leakage and minimizing heat transfer, the insulated system keeps indoor spaces cooler in the summer and warmer in the winter, lowering heating and cooling demands. Combined with the reflective, white Duro-Last PVC membrane, which deflects a significant portion of the sun’s heat, the system enhances overall energy efficiency, improves indoor comfort, and reduces long-term HVAC costs.

Furthermore, the reflective properties of Duro-Last and Goliath retrofit systems enhance energy efficiency by reducing energy consumption and extending the lifespan of HVAC equipment. Whether you’re looking to retrofit an existing commercial or residential, low-sloped or flat roof, Watertite Roofing is here to help you benefit from Duro-Last® and Goliath roofing solutions.

Metal Roof Solutions That Will Last Decades

Durability is at the core of every Duro-Last and Goliath retrofit system. Engineered for watertight protection, these roof systems resist the common issues that shorten the lifespan of metal roofs. With hidden fasteners and a monolithic seal, they provide superior performance against rain, snow, and extreme temperatures.

The combination of structural strength, efficient insulation, and reflective surfaces ensures that your roof is built to last for decades with minimal maintenance. Thus, retrofitting an existing roof is an economical and functional solution for property owners.

Metal Roof Retrofit Ontario Installation Process

We handle every metal roof retrofit project in Ontario with precision, safety, and efficiency. The process begins with a comprehensive on-site inspection to evaluate the roof’s slope, insulation quality, and overall condition. Our specialists identify areas of concern such as corrosion, seam separation, or insulation gaps before recommending the most effective retrofit approach.

On low-sloped metal roofs, we install insulation and overlay a PVC roofing membrane system directly on top of the existing surface — eliminating the need for a full tear-off. This lightweight, flexible system offers superior waterproofing, reduces installation time, and minimizes disruption to business operations. Each retrofit includes a high-performance moisture barrier and upgraded insulation, improving energy efficiency by up to 30% compared to outdated materials.

Our certified installers ensure every weld, seam, and flashing is watertight for lasting protection. The result is a durable, low-maintenance roofing system that helps reduce heat loss, improve insulation performance, and extend the roof’s lifespan for decades.

Structural Integrity Check: Retrofit Roofing on Older Buildings

Before installing a metal roof retrofit, we always conduct a full structural integrity check, especially on older commercial or industrial buildings across Ontario. Our staff inspect the deck, trusses, and framing connections to verify they can handle the additional weight and uplift of a code compliant metal roof. This ensures every retrofit meets Ontario Building Code standards and performs safely under heavy snow loads — which can exceed 20 pounds per square foot in some regions.

This stage prevents premature failure and reinforces long-term safety. When paired with standing seam roofing, the retrofit provides better weather resistance and reduced maintenance needs — a crucial advantage for aging structures that still have solid bones but need a modern roofing upgrade.

PVC Roof Overlay for Low-Sloped Metal and Flat Roofs

For property owners dealing with aging flat or low-sloped metal roofs, our PVC overlay retrofit system offers a cost-effective and sustainable solution. Instead of replacing the existing roof, we mechanically fasten and heat-weld a new PVC membrane directly over it, creating a watertight barrier that resists ponding water, UV damage, and corrosion.

The PVC membrane’s reflective surface also helps reduce heat absorption, cutting cooling costs during Ontario’s hot summers and improving overall energy efficiency year-round.

On average, these conversions can extend a roof’s lifespan by 25+ years with minimal maintenance. For building owners managing warehouses, factories, or large retail spaces, a sloped metal retrofit is not only an economical and functional solution, but also an investment in long-term energy savings and peace of mind.

Should You Repair, Retrofit, or Replace a Metal Roof?

Your choice will depend on the condition of your existing roof and the nature or extent of the damage. Surface damage, such as rusting or lose screws, may be repairable. However, extensive deterioration of the existing roof and underlying structure may necessitate a complete replacement.

Pre-engineered steel commercial structures with metallic roofs gained popularity in Ontario in the 1980s. In most cases, the type of roofs installed on these structures was considered ‘screw-down’ metallic roofs. They offer lasting protection against the weather because of their durability and resistance to weather-related damage.

Fast-forward five decades, and these early ‘screw-down’ metallic roofs are beginning to show signs of extensive wear and failure. This signals the end of the roof’s useful life. Leaks may be occurring frequently, or you have noticed other signs of damage. So, should you repair, retrofit, or replace the existing commercial sloped or flat roof? Here’s what to keep in mind.

Roof Repairs

Before you schedule repairs for your roof, consider the fact that the roof will continue to deteriorate due to natural wear and tear. At some point, you’ll need to replace it. Think about the money spent on repairs and compare it to the cost of retrofitting or replacing it.

In addition, the insulation layers and other materials beneath your metal roof may also get damaged if roof issues like moisture infiltration and leaks aren’t addressed. Serious damage to the underlying structure may necessitate a complete roof replacement.

Skilled Roofers, Fair Costs & Guaranteed Workmanship

Give us a call at +1 (800) 263-8452 to book a free, no-pressure quote. We’ll take the time to understand your roofing needs, inspect your current setup, and provide honest, expert advice—no upsell, no shortcuts. With Watertite Roofing, every metal roof retrofit is built to last and backed by guaranteed workmanship.

FAQS