5 Reasons to Choose an Inverted Roof

As homeowners realize the many benefits offered by inverted roofs, this roofing option is becoming a more and more popular alternative to traditional roofs. The term “inverted roof” refers to a roof construction type, where the waterproofing layer is located underneath the insulation rather than above it – as opposed to other types of roofing. As such, inverted roofs effectively keep the entire roof construction, including roof covering, at moderate temperatures during hot summer months and at warm temperatures during the colder winter season.

Also commonly known as an “upside down” or “protected membrane” roof, inverted roofs contain insulation that can ensure outstanding thermal performance, resist water absorption, remain unaffected by thaw and freeze cycles, stay protected from mechanical and UV damage, withstand surface traffic, and more. While in traditional roofing construction, the insulation is placed under the protected membrane, inverted roofs are created with a waterproofing layer, commonly a liquid-applied membrane, located beneath the insulation. Then, insulation boards are loose-laid over the membrane and weighted down with gravel ballast, paving slabs, or soil medium in the case of vegetative or “green” roofs.

Why Choose an Inverted Roof for Your Building?

There are numerous reasons as to why one should choose to install an inverted roof, including:

1. Cut total costs over the roof lifetime.

Installing a new roof presents a significant investment, as it can impact nearly every other feature and function of a building. In North America, the average lifespan of a roof system is approximately 15 years, with the commercial roof’s depreciation period of 35 years. However, delaying a roof replacement by 10 years can lead to hundreds of thousands of dollars in savings. The good news is that inverted roofs typically last considerably longer than traditional ones.

In addition, inverted roofs come with notably lower maintenance costs as compared to conventional low-slope roofs. This is largely due to the insulation within the inverted assembly that works to protect the roof membrane against possible mechanical damage sustained during or after construction, as well as extreme temperature fluctuations that lead to stress. In addition, the insulation effectively protects against ultraviolet radiation that often leads to premature failure.

As a result of this enhanced durability and the reduced annual energy costs, installing an inverted roof can lead to the total reduction in roof-life costs of up to 22 percent.

2. Better stormwater management.

As weather patterns are becoming more unpredictable as a result of climate change, building resilience is relying more and more heavily on the ability to handle stormwater overflow. Cities across North America, from Toronto to Vancouver, are starting to take action to prevent stormwater and sewage flows from damaging the urban environment. As every fraction of an inch of rain is capable of overwhelming some combined sewer systems, cities are taking action to prevent overflow from polluting local waterways and rivers.

By installing a green roof on your building, you can help to reduce the burden placed on the municipal sewage system, as the green roof would absorb much of the rainwater that falls on the roof. Depending on the climate, such roofs are typically able to retain 40 to 90 percent of stormwater runoff from the roof, which makes them a cost-effective way to eliminate or reduce overflow. Choosing a blue or green roof assembly capable of supporting water-saturated vegetation without absorbing the water is critically important to the integrity of the roof. DuPont™ Styrofoam™ Brand XPS Insulation, the inventor of the inverted roof, has been the preferred choice for green roof assemblies for over 40 years, as it is able to provide long-term thermal protection and effectively resist moisture.

3. Improve occupant satisfaction.

In the modern age, people tend to spend more time than ever before in urban environments, which results in a growing need to reconnect with nature.  With traditional roof construction, people often tend to feel cut off from nature. On the other hand, turning a roof into a walkable, usable space with natural amenities can help to bridge this gap and increase the overall satisfaction of your building occupants.

By establishing a more park-like, outdoor aesthetic of your building, you are more likely to keep the occupants happy, healthy, and helpful. For example, according to one report, employees who work in environments filled with natural elements are 8 percent more productive and report a 14 percent higher level of well-being. In addition, this can serve as a key differentiator from traditional buildings, thus helping to attract other tenants and businesses.

4. Improve environmental performance.

Today, 5 percent of overall landfill waste in the U.S. comes from the roofing industry, leading to the astounding 50 billion pounds per year. Luckily, the enhanced energy efficiency and longevity of inverted roofs is not only good for the wallet but also good for Mother Earth. Because the roof’s insulation, fabric, and ballast are loose-laid, they can be easily reused, which helps to reduce downstream waste resulting from the construction, maintenance and repair, and demolition of the building. 

With inverted roofs, insulation is placed on top of the membrane, providing a perfect foundation for a garden, terrace, or green roof on the top of the building. According to research, even on a sunny and hot day, the roof surface’s temperature underneath a green roof can be cooler than the air around it. This can help to minimize the effects of the solar energy on the temperature inside the building, thus reducing the urban heat island effect. Reduced urban heat island effect means that less solar energy is reflected back into the atmosphere, which minimizes the contributions to global warming. In addition, reduced energy consumption leads to a lighter burden on the grid, which often means that less natural gas or fossil fuels must be burned in order to generate power.

5. Preserve local habitat.

In addition to its numerous benefits to people, a green roof assembly can also benefit local wildlife. As cities expand and continue to encroach on nature, it is essential to incorporate elements of natural environments within urban landscapes. 

Green roofs are excellent at mimicking natural environments, as they serve as urban refuges for insects and migrating birds. In addition, green roofs play an important role in supporting local biodiversity, as they create homes for animals like rabbits and squirrels. For example, in Basel, Switzerland, green roofs have become an integral part of the city’s biodiversity strategy. As such, some of the city’s green roofs have formed dense microhabitats, which are able to support as many as 40 spider and 79 beetle species – and 7 of the spiders and 13 of the beetles are endangered.

Enjoy the Benefits of an Inverted Roof with the Help of Royal Roofing Inc.

In order to enjoy the longevity and other benefits of an inverted roof, a strong insulation choice is of the utmost importance. Luckily, an extruded polystyrene (XPS) insulation is able to deliver excellent long-term performance over the lifetime of the roof. Browse the roofing solutions offered by Royal Roofing Inc. to find the optimal choice for your project.