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Best Roofing Materials for Flat Roofs


May 25, 2016

Most commercial buildings, and many multifamily residences, have flat or low-slope roofs. Such roofs pose challenges that regular, sloped roofs do if only because sloped roofs more readily direct rain and snow to the ground faster than any flat surface. Whether building new or repairing an existing flat roof, Denver roofing companies can help you choose which materials will serve your building’s needs and fit your budget.

Materials: Flat roof materials come in three basic types--single ply, built-up, and spray-on/paint-on. Single-ply membranes, especially EPDM membranes, are the most popular flat roof material and cautions that quality and longevity among products vary, with thicker products being more durable.

Cost: In materials cost, flat roofs are less expensive than sloped roofs. Single-ply membranes generally range from $1.50 to $2.00 per square foot (excluding insulation). However, materials cost isn’t the only factor to consider when installing a roof. Maintenance and longevity strongly affect life cycle cost.

Single-ply roofing requires either glue or screws to affix the membrane to the roof. Experts advise hiring a professional installer experienced in flat roofing to ensure seams are properly glued. Poorly glued seams leak. The benefit of EPDM rubber is that it requires no special equipment for installation.

Installation costs for flat roofs range from $5.50 to $7.50 per square foot, depending partially on the material used, roof size, and complexity of the installation. A reputable Denver roofer will provide you with a written estimate.

Longevity varies widely among flat roofing materials. PVC, the second most popular flat roofing material, features heat-welded seams and a flexibility that withstands thermal movement. More expensive than EPDM, it can last over 30 years, although manufacturers’ warranties generally specify 25 years. EPDM’s longevity averages 10 to 15 years, with most such roofs failing due to seam separation and ponding water. Single-ply materials are also susceptible to punctures, which then lead to leaks. Thicker membranes are more difficult to puncture, as well as heavier.

PVC membranes are the easiest of single-ply materials to maintain and repair. Their heat-welded seams remain weldable throughout their service life, which makes any repair, maintenance or modifications to install new equipment fast and simple. The glue on EPDM roofs degrades, which necessitates applying a special roofing tape over all seams every seven to 10 years. Find a Denver roof repair company that is skilled in flat roof maintenance to be sure the job’s done right.

Flat roofs require additional structural engineering to accommodate the weight of the roof itself, rooftop equipment (HVAC units, solar panels, etc.), and any other uses. In an urban environment, flat roofs make great spaces that serve as outdoor spaces for recreation, socializing, and gardens. Experts suggest using 80 mil or thicker PVC membranes beneath green roofing applications because their hot-welded seams will not leak under the layers of soil and plants.

Other benefits of flat roofs include energy efficiency and reduced environmental impact. PVC roofing canreflect up to 90 percent of heat back into the atmosphere, reducing the building’s summer air conditioning costs. PVC roofing can be recycled, reducing landfill space. Rooftop gardens improve air quality, reduce heat, and provide recreational, social, and psychological benefits in an urban environment.

Experience is crucial when installing, maintaining, and repairing flat roofs. Big Creek Roofing and Restoration brings 15 years of experience in the installation, repair, and replacement commercial roofs. Call (303) 877-8369 for a consultation.