Clogged roof drains cause more flat-roof leaks in Winchester, KY than storm damage does, and fall leaf drop is exactly when they clog — which makes September and October the two months a five-minute drain check pays off the most.
Why Do Commercial Roof Drains Clog in the Fall?
Leaves, seed pods, and grit wash toward low points and drain bowls on a flat roof, and a blocked drain turns normal rain into standing water within a single storm.
Clark County’s mature tree cover means most commercial buildings here deal with real leaf drop between late September and November, and a low-slope roof concentrates all of it at the drains, scuppers, and gutter outlets rather than letting it wash off the edge the way a pitched residential roof does. Once a drain is even partially blocked, water backs up around it, and standing water is exactly what stresses seams, flashing, and any spot where the membrane isn’t perfectly flat. NRCA’s roofing guidelines note that most low-slope systems depend entirely on unobstructed drainage — there’s no slope steep enough to compensate for a blocked outlet.
What a Fall Drain Check Actually Involves
Clearing a drain strainer and bowl by hand takes a few minutes per drain and doesn’t require a full roof inspection to justify. The useful habit is checking after the first hard leaf drop and again once trees are bare — two visits catches both waves of debris before either one sits long enough to compact into the drain body.
For buildings already on a preventive maintenance program, drain clearing is typically bundled into the fall visit alongside the membrane and flashing check. For everyone else, it’s one of the cheapest line items on a service call — clearing drains costs far less than the leak repair and interior damage that a fully blocked drain leads to after a hard rain.
Common Questions
How do I know if my roof drain is clogged?
Standing water that doesn’t drain within 48 hours of dry weather is the clearest sign. Visible leaves or debris piled around a drain bowl is worth clearing even before water starts pooling.
Can I clear a roof drain myself?
Clearing visible debris from a drain strainer is reasonable for building staff to do. A drain that’s still backed up after clearing the strainer usually means a blockage further down the line, which needs a roofer or plumber to check.
Does ponding water from a clogged drain void my roof warranty?
It can — most manufacturer warranties exclude damage from ponding water that a maintenance issue like a clogged drain caused. See our ponding water and warranty page for specifics.
Related: Roof Drainage & Ponding | Preventive Maintenance Program | Winter Roof Prep Checklist
Not sure when your drains were last cleared? Schedule a free inspection or call or text (859) 310-1209.
Source: National Roofing Contractors Association, Roofing Guidelines.
Last updated: September 7, 2026