What Is the Lifespan of a Flat Roof?

What Is the Lifespan of a Flat Roof?

A properly maintained flat roof can last for decades, depending on the materials. A built-up roof or layers of modified bitumen can last for up to 20 years. Lightweight thermoplastic polyolefin or spray-on coatings of polyurethane foam, acrylic or silicon have a similar lifespan. The longest-lasting roof materials such as ethylene propylene diene monomer (EPDM) and polyvinyl chloride (PVC) roofing may endure for up to 10 more years than that, depending on the inspection and maintenance schedule. Learn more about the factors that determine the longevity of roofing materials to stay ahead of commercial roof repair and replacement.

Factor In the Material

The materials used to make a flat roof play a large part in determining its lifespan. A multi-layer built-up roof consisting of waterproof material, hot tar and gravel can last for 15 to 20 years. Roofs consisting of three to five layers of modified bitumen have a slightly shorter average lifespan of 10 to 15 years. These materials are heavy and may not be the best choice for every building.

Lightweight single-ply roofing can last for as long or longer than layered roofs depending on the properties of the material, the design of the roof and reliance on commercial roof repair. EPDM and TPO roofing generally last anywhere from 10 to 20 years, while TPO roofs have stronger seams than EPDM roofing. With proper maintenance, a PVC roof can last up to 30 years.

Consider the Weather

A flat roof exposed to extreme temperature fluctuations, high winds and heavy precipitation may have a shorter lifespan than the same roofing material in another climate. Flat roofing made of asphalt is prone to expanding and contracting as the temperature changes, putting more stress on the flashing designed to prevent wind damage and leaks. High temperatures can also cause tar to blister, which causes premature wear.

Single-ply materials have properties that may be better suited to different regions. EPDM typically comes in black, which can be helpful for retaining heat and melting snow in cold weather but traps excess heat in warm weather. This material is also available with a light-colored coating for a higher price. TPO is more readily available in white or light gray colors for energy efficiency. PVC and spray-on coatings are available in any shade necessary and can provide durable roofing solutions for any climate.

Protect the Structure

Commercial roof repair may involve patching minor leaks. More extensive impact damage or wear can cause issues that expose a structure to a greater risk of major water damage or even roof collapse. If an older roof has many patches and suffers further impact or damage caused by pooling, a roof replacement may be more effective than further repairs for stopping leaks and lowering the risk of structural damage.

A flat roof with one inch of standing water across an area 20 feet by 20 feet has 2,000 pounds of additional weight. Excess weight can damage a roof made out of any material at any age. If a roof cannot drain properly even with regular maintenance and retroactive adjustments to the slope, a new roof may be necessary to prevent deterioration or a collapse.

Resolve Underlying Problems

A roof that does not drain properly is only one of many potential underlying problems. Structural issues may be too extensive for commercial roof repair and require the replacement of a roof sooner than the expected lifespan for a particular material. A structure with foundation problems may settle or shift more than a solid build. This can cause a roofing membrane to buckle and make a building structurally unsound. Roofing specialists can recommend the best materials and design for any commercial building.

Built-up roofing is much heavier than single-ply materials. A modified bitumen roof also requires installation of three to five layers of heavy materials. Single-ply EPDM, TPO, PVC or a spray-on coating are much lighter options suitable for a wider range of structures. Roll-on membranes require a full installation starting with a steel deck, insulation and roof board. EPDM attaches with bonding cement, while TPO and PVC use adhered or attached membranes. It may be possible to apply a spray-on roof coating made of polyurethane, acrylic or silicone over an existing roof.

The choice of material, structural requirements and location of a commercial property may determine whether a roof lasts for the duration of the average span of time for the material. It is necessary to maintain any type of roof to reach the longest lifespan. Clogged drainage systems are easy to avoid and pooling water can undermine any roof. Any damage such as blisters, cracks, punctures or splits should be quickly patched or repaired by trained professionals. Regular inspections and commercial roof repair enable any commercial property owner to keep a flat roof in good condition for years to come.