Flat Roof FAQ

A flat roof is a roofing system with a slope of less than 2:12 (less than about 10 degrees). Despite the name, flat roofs are not completely flat — they have a slight pitch (typically 1/4 inch per foot) to allow water drainage. Flat roofs are common on commercial buildings, industrial facilities, and many residential properties in cities like St. Louis. They are covered with waterproof membranes such as TPO, EPDM, PVC, modified bitumen, or built-up roofing (BUR) rather than the shingles used on steep-slope roofs.

Flat roof costs in St. Louis vary by project type. Residential flat roof replacement typically costs $5,000-$15,000. Commercial flat roof replacement costs $5-$12 per square foot. Flat roof coating and restoration costs $2-$5 per square foot. Flat roof repairs range from $300-$2,500 depending on severity. Factors affecting cost include roof size, system choice, existing conditions, access difficulty, and whether a tear-off is needed. Contact St. Louis Flat Roofing Company for a free, detailed estimate specific to your property.

The most common causes of flat roof leaks are: ponding water from inadequate drainage, deteriorated or cracked membrane material, failed flashing around roof penetrations (vents, pipes, HVAC units), seam separation where membrane sheets join, storm damage from hail or wind, and clogged or damaged drains and gutters. In St. Louis, freeze-thaw cycles during winter are a major contributor to flat roof leaks because expanding ice stresses seams and flashings. Regular inspections help catch these issues before they cause interior damage.

The best flat roof material depends on your building and priorities. TPO (Thermoplastic Polyolefin) is the most popular commercial choice — it is energy-efficient, durable, and cost-effective. PVC is ideal for buildings with chemical exposure or rooftop grease exhaust. EPDM (rubber) is a proven, affordable option with a long track record. Modified bitumen is popular for residential flat roofs in St. Louis due to its durability and ease of repair. A qualified flat roof contractor can recommend the best material for your specific situation.

Flat roofs are an excellent choice for residential properties and are a defining feature of St. Louis architecture. Benefits include lower construction cost compared to pitched roofs, usable rooftop space for decks or gardens, easier installation of solar panels and HVAC equipment, and a modern aesthetic. The key to a successful residential flat roof is proper installation by a flat roof specialist, adequate drainage design, and regular maintenance. Thousands of St. Louis homes have flat roofs that perform reliably for decades.