The terms “water-shedding” and “water-resistant” are terms that, while they sound similar, have different applications on roofing systems. Read on as the roofing contractors at Classic Remodeling Corp. take a look at the differences between these terms, and why they’re important.
Water Shedding Vs. Water Resistance
Water-shedding roofs, also known as hydrokinetic roofs, utilize gravity to shed rainwater into the gutters. Slopes of 3/12 or greater force water to move quickly. The higher the slope, the more efficient it is. The higher the slope, the faster it sheds rainwater, therefore, the gutters need to be properly sized for the roof. Water-shedding roofs typically rely on a secondary membrane, or underlayment, to prevent moisture intrusion.
Water-resistant roofs, or hydrostatic roofs, have low slopes, which means they can’t shed rainwater like sloped roofs do. Low-slope and flat roofing systems typically have a welded top layer, which provides water resistance, as this type of roofing tends to have standing water when not immediately drained. It’s important to note that water resistance is different from waterproofing, as roofing membranes are not designed to be submerged for extended periods.
Protection Against Water Intrusion
Both roofing styles are designed to protect the building from water intrusion. Of the two, the water-shedding type is the more practical, as it offers more flexibility in terms of material. The outer roofing surface doesn’t need to be watertight to prevent water intrusion, which gives it more flexibility on the choice of roofing materials.
However, water-shedding roofs become impractical the bigger the building becomes. This is where low-slope water-resistant roofs are suitable for, as steep-sloped roofs would be comically large: maintenance and repairs would be difficult and impractical.
While low slopes are more practical, using the same materials like asphalt shingles and shakes would make it easily susceptible to water intrusion. Therefore, monolithic roofing systems, such as TPO, EPDM and bitumen are ideal. Some of these roofing systems can be installed ballasted, welded or fully adhered depending on roofing requirements and local climate conditions.
Classic Remodeling Corp. is your leading provider of roof repair and installation services. Give us a call at (201) 487-1666 or fill out our contact form. We serve customers in Hackensack, NJ, and nearby areas.