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Commercial Roof Overlay: Systems, Costs and Guarantees


A commercial roof overlay refers to a roofing method where a new layer of roofing material is installed directly on top of an existing roof. This overlay serves as an additional protective barrier, enhancing the durability and longevity of the roof. It is a cost-effective solution that avoids the need for complete roof replacement. The overlay can be applied to various types of commercial roofing systems, providing improved weather resistance and extending the life of the roof.

What Are The Best Flat Roof Overlay Systems?

There are several flat roof overlay systems that are commonly used and recognised for their performance and durability. Some of the best flat roof overlay systems include elastomeric coatings, EPDM (ethylene propylene diene terpolymer), TPO (thermoplastic olefin), PVC (polyvinyl chloride), and modified bitumen membranes. These systems offer excellent waterproofing properties, UV resistance, and flexibility to accommodate thermal movement. The choice of the best system depends on factors such as budget, building requirements, and environmental conditions. It is recommended to consult with a roofing professional to determine the most suitable overlay system for a specific project.

The best commercial roof overlay system can vary depending on specific project requirements and considerations. However, elastomeric roof coatings are often regarded as an excellent option for commercial roof overlays. Elastomeric coatings, such as acrylic or silicone-based coatings, offer exceptional durability, flexibility, and weather resistance. They provide a seamless, protective barrier that can extend the life of the roof, improve energy efficiency, and withstand harsh environmental conditions. It is advisable to consult with a roofing professional to evaluate the specific needs of the building and determine the best commercial roof overlay system, including the suitability of elastomeric coatings for the project.

Other excellent systems include EPDM (ethylene propylene diene terpolymer), TPO (thermoplastic olefin), PVC (polyvinyl chloride), and modified bitumen membranes.

Are There Metal Roof Overlay Systems?

Yes, there are metal roof overlay systems available for commercial buildings. These systems are designed to be installed directly over existing metal roofs, providing an additional layer of protection and improving the performance of the roof. Metal roof overlay systems typically involve applying a new metal panel or membrane on top of the existing roof, enhancing its durability, weather resistance, and energy efficiency. This approach is often chosen as a cost-effective alternative to full roof replacement while still achieving significant improvements in the performance and longevity of the metal roof.

What Is A Pu Overlay Roof System?

A PU (Polyurethane) overlay roof system refers to a type of commercial roof overlay that utilises polyurethane coatings. PU overlay systems involve applying liquid polyurethane coatings directly onto an existing roof surface, creating a seamless and durable protective layer. The polyurethane material cures and forms a flexible, waterproof membrane that enhances the roof's resistance to water, UV rays, and other environmental factors. PU overlay systems are known for their excellent adhesion, long-term durability, and ability to accommodate roof movement. They can be applied to various types of roofs, including flat roofs, to extend their lifespan and improve performance.

Is An Asphalt Overlay Possible?

Yes, an asphalt overlay is possible for certain types of commercial roofs. An asphalt overlay involves applying a new layer of asphalt material directly over an existing roof surface. This method is commonly used for built-up roofs (BUR) or modified bitumen roofs. The process typically includes cleaning the existing roof, applying a primer, and then installing a new layer of asphalt using hot asphalt or a modified bitumen membrane. An asphalt overlay can provide additional waterproofing and extend the life of the roof, especially if the existing roof is still in relatively good condition. However, it's essential to consult with a roofing professional to assess the feasibility and suitability of an asphalt overlay for a specific commercial roof.

How Do I Know If My Roof Is Suitable For An Overlay?

Determining the suitability of a roof for an overlay depends on various factors and requires a thorough assessment by a roofing professional. Here are some key considerations to help determine if your roof is suitable for an overlay:

  1. Condition of the existing roof: The existing roof should be in relatively good condition with minimal damage, structural issues, or extensive deterioration. Any underlying problems should be addressed before considering an overlay.
  2. Compatibility: The current roof material should be compatible with the overlay system you intend to use. Different overlay systems are suitable for specific roof types, such as asphalt overlays for built-up roofs or elastomeric coatings for various roof substrates.
  3. Structural capacity: The roof structure should have sufficient load-bearing capacity to support the additional weight of the overlay system. It's important to verify that the existing structure can accommodate the increased load.
  4. Moisture and insulation considerations: The existing roof should have proper moisture management and insulation. Any moisture issues or inadequate insulation should be addressed before proceeding with an overlay.
  5. Building codes and regulations: Ensure that an overlay complies with local building codes and regulations. Some jurisdictions may have specific requirements or restrictions for roof overlays.

It is advisable to consult with a qualified roofing professional to conduct a thorough inspection and provide an expert assessment of your roof's suitability for an overlay. They will consider these factors and provide recommendations tailored to your specific roof condition and requirements.

Is A Commercial Roof Overlay Disruptive?

No, a commercial roof overlay is not disruptive compared to the alternative of a complete roof replacement. Since an overlay involves installing the new roofing material over the existing roof, it eliminates the need for extensive tear-off and disposal of the old roof. This can minimize disruptions to the building occupants, reduce noise, and limit the potential for interior damage during the installation process. However, it's important to note that some level of disruption is still expected during any roofing project, and it's recommended to communicate with the roofing contractor to plan and mitigate any potential disruptions during the overlay installation.

Do Commercial Overlays Extend A Roofs Lifespan?

Yes, commercial roof overlays can extend the lifespan of a roof when properly installed and maintained. The amount the lifespan of a roof can be extended by an overlay can be as much as 20 years. The overlay serves as an additional layer of protection over the existing roof, providing improved waterproofing, enhanced durability, and increased resistance to weathering and UV damage. By addressing existing issues and reinforcing the roof's integrity, a well-installed overlay can help extend the lifespan of the roof, delaying the need for a complete roof replacement. However, it's important to note that the longevity of the overlay will depend on factors such as the quality of the materials, installation techniques, and ongoing maintenance of the roof. Regular inspections and maintenance are still necessary to ensure the overlay continues to perform effectively and maximize the lifespan of the roof.

How Much Does A Flat Roof Overlay Cost?

The cost of a flat roof overlay in the UK can vary depending on several factors, including the size of the roof, the type of overlay system used, the complexity of the installation, and the specific requirements of the project. Generally, the cost of a flat roof overlay in the UK can range from £50 to £120 per square meter. However, it's important to note that this is a rough estimate and the actual cost may be higher or lower based on the factors mentioned earlier. It is recommended to obtain quotes from reputable roofing contractors in your area to get a more accurate cost assessment for your specific project.

How Is A Commercial Roof Overlay Installed?

The installation process of a commercial roof overlay may vary depending on the specific type of overlay system being used. However, here is a general outline of the steps involved in installing a commercial roof overlay:

  1. Inspection and preparation: The existing roof is inspected to identify any underlying issues or damage that needs to be addressed. The roof surface is thoroughly cleaned and prepared for the overlay installation.
  2. Application of primer: A primer is applied to the cleaned roof surface to ensure proper adhesion of the overlay material.
  3. Overlay installation: The chosen overlay material, such as a liquid coating or membrane, is applied according to the manufacturer's guidelines. This can involve spraying, rolling, or spreading the material over the roof surface. The overlay is typically applied in multiple layers to achieve the desired thickness and coverage.
  4. Detailing and flashing: Flashings and other roofing details, such as edge terminations, penetrations, and transitions, are addressed to ensure a watertight and seamless installation.
  5. Curing and final touches: The overlay material is allowed to cure and bond to the existing roof surface. Any necessary finishing touches, such as trimming, sealing, or coating, are performed to complete the installation.

It's important to note that the installation process may require skilled roofing professionals with expertise in the specific overlay system being used. Following proper installation techniques and manufacturer guidelines is crucial to ensure the effectiveness and longevity of the commercial roof overlay.

Are Roofing Overlays Guaranteed?

The guarantees or warranties for commercial roofing overlays can vary depending on the manufacturer of the overlay material and the roofing contractor installing it. It's common for manufacturers to provide warranties for their overlay products, which typically cover defects in materials or workmanship.

The length and specific terms of these warranties can vary, so it's important to review the warranty documentation provided by the manufacturer. Respectable companies such as Alphateq Waterproofing offer guaranteed on commercial roof overlays of up to 20 years.

Is A Commercial Roof Replacement A Better Option Than An Overlay?

Whether a commercial roof replacement or an overlay is a better option depends on various factors such as the condition of the existing roof, budget constraints, long-term goals, and the advice of roofing professionals. Here are some considerations:

  1. Roof condition: If the existing roof has extensive damage, structural issues, or has reached the end of its lifespan, a complete roof replacement may be the more appropriate choice to ensure a long-lasting and reliable roofing system.
  2. Budget: Roof replacements generally involve higher costs compared to overlays, as they require complete tear-off of the existing roof and installation of a new roofing system. If budget constraints are a concern, an overlay may be a more cost-effective option to address minor issues or extend the lifespan of the roof.
  3. Long-term goals: If you have long-term plans for the building and want a fresh start with a new roofing system that offers improved performance, energy efficiency, or design options, a complete roof replacement may be the preferred choice.
  4. Professional advice: It's important to consult with reputable roofing professionals who can assess the condition of the existing roof, evaluate the feasibility of an overlay, and provide recommendations based on your specific needs and goals.

Ultimately, the decision between choosing a commercial flat roof replacement and an overlay should be based on a thorough evaluation of the roof's condition, your budget, and your long-term objectives. It's recommended to seek the guidance of experienced roofing professionals to help determine the best course of action for your commercial roofing needs.

Is A Flat Roof Patch Repair Better Than An Overlay?

The answer to whether a flat roof patch repair is better than an overlay depends on the extent of the damage and the overall condition of the commercial roof. A patch is a type of commercial roof repair which is suitable for localised damage and can be a cost-effective solution. In contrast, an overlay provides a more comprehensive and long-term solution for roofs with extensive damage or coming towards the end of their lifespan.

Are Commercial Roof Overlays Durable?

Yes, commercial roof overlays can be durable and provide extended protection for the underlying roof. The durability of the overlay depends on factors such as the quality of materials used, proper installation, and regular maintenance.

Can An Overlay Withstand Heavy Foot Traffic?

An overlay's ability to withstand heavy foot traffic depends on the specific overlay system and its design. Some overlays are engineered to be durable and capable of handling foot traffic, while others may require additional protective measures or restrictions to prevent damage.

Can An Overlay Be Used On A Commercial Roof Used As A Service Deck?

The use of an overlay on a commercial roof being used as a service deck depends on the specific overlay system and its design. Some overlays are suitable for service deck applications and can provide additional protection, while others may not be designed for such purposes.

How To Maximise The Service Life Of A Roof Overlay?

To maximise the service life of a roof overlay, regular inspection and commercial roof maintenance works are crucial. This includes addressing any issues promptly, ensuring proper drainage, and conducting routine cleaning to prevent debris build-up and potential damage to the overlay system.

Is It Easy To Repair A Commercial Roof Overlay?

The ease of repairing a commercial roof overlay depends on the specific type of overlay system and the nature of the repair needed. Some repairs may be relatively straightforward, such as patching small areas, while others may require more extensive work and expertise.

Need Help With A Commercial Roof Overlay?

If you would like a quotation or any information about a commercial roof overlay please get in touch with using our contact form or call us now on 01277 375 511. One of our experienced team of commercial roofing experts will be happy to help.