It’s easy to love your roof when it’s relatively new and doing its job. How long that honeymoon period of roofing affection lasts depends a lot on the type of roof you have over your head—while some roofing systems, like metal roofs or slate tile roofs, can last for more than 50 years with proper maintenance, those of us who have flat or low-slope roofs on our homes aren’t so lucky. While flat-roof systems have an official lifespan of about 25 years, anyone who actually has a flat roof knows you’re lucky if you get a decade out of them before they start to leak and otherwise show their age. There’s a reason roofing companies always offer a 10-year warranty on these roofs, after all.
Even on a flat roof, the most common sources of leaks are the seams—spots where there are changes in plane, flashing, skylights, or vent pipes. If your roof starts leaking those are the places where you begin your inspection, so it makes sense that if you eliminate the seams, you eliminate the problem. If you have a flat roof on your house that needs to be repaired or replaced, it’s worth it to consider what’s known as a seamless roof system or a monolithic roof.
What is a seamless roof systems?
A seamless roof system (sometimes called a “monolithic” roof) is just what it sounds like: A roofing membrane that is one continuous layer without any seams. These systems are self-flashing, meaning they don’t require any additional seals around vents or chimneys. It’s typically applied in one of two ways:
Liquid. Many seamless roofing systems are applied as a liquid (silicone, acrylic, or urethane), often using reinforcing materials made from fiberglass to increase strength. The liquid is rolled or sprayed onto the roof surface and worked into all seams and gaps, then dries to a seamless and waterproof finish.
Spray foam. Another approach is sprayed-on polyurethane foam, which expands into all voids and seams, sealing them off, then dries to form a sturdy, waterproof layer.
It’s important to note that these aren’t just the roof coatings you can buy at a hardware store that can help extend the life of your flat roof, which are applied like paint. While the application process can be superficially similar, they’re complex systems that need to be installed precisely in order to get a truly seamless and waterproof result.
When installed as new, many seamless roofing systems involve layers of reinforcing membrane that are sandwiched between liquid applications. But these roof systems can also be applied over an existing flat roof, if the roof is still in decent shape, including shingled roofs, metal roofs, or rubber roofs—as long as they’re low-slope or flat. Roofs with a lot of pitch can still have a seamless system applied, but the results are usually less than ideal, as these systems are designed for flat areas. Companies like Kemper System and Everseal have roofing systems that involve repairing and reinforcing an existing flat roof and then applying a monolithic coating that seals everything into a seamless installation, typically with a warranty between 20 and 50 years.
Benefits
Seamless roofing systems offer a lot of advantages over traditional roofs:
Durability. As noted, warranties for seamless roof systems can be as long as 50 years, and typically last at least 20 years without the need for notable maintenance or repair. Seamless roofing systems are flexible—they expand and contract in the heat and cold along with your roof, which reduces the chances of cracking or other leaky damage.
Energy efficiency. These roofing systems act as reflective barriers that keep your roof cool and protect the roofing deck from damaging solar radiation. This extends the life of the roof and also helps keep the house cooler, reducing energy costs.
Costs. The low maintenance and long life of a seamless roofing system usually translates to a lower cost over time, since you won’t need to have roofers come by every few years to fix up leaks, or replace the roof every decade or so.
