Commercial Gutters | Roof Drainage

The Gutter or Roof Drainage system on your commercial or industrial building has a huge impact on the overall performance of your roofing system. Without a properly designed or functioning roof drainage system large amounts of water can accumulate on your flat roof or overflow metal roof gutters. With this close relationship, it’s not uncommon for a gutter issue to be misdiagnosed as a roofing issue.

To define roof drain failure an example would be Kemper Arena in Kansas City. The roof spans 324 ft X 360 ft (116,640 sqft) and in 1979 the roof collapsed during a rain storm. The wind was blowing 70-80 MPH and the rain was so heavy as the storm dumped 3.5 inches of rain in the first hour. That equates to about 1,200 tons (2.4 million lbs) of water weight which is a lot! There was not a sufficient amount roof drains in place to evacuate that amount of water.  The roof then deflected and the roof collapsed. 1 inch of ponding water on a 16,000 sqft flat roof is approx. 34 tons (68,571 lbs). As a military veteran I can tell you that would be like setting a Bradley Armored Fighting Vehicle on your roof. Would you trust it?  Imagine what 1 or 2 inches of rain ponding on your would weigh?

To define metal gutter failure an example would be a commercial warehouse in Kansas City, Ks. This is standing seam metal roof spanning 496 ft X 252 ft (124,992 sqft) and in 2010 the metal gutter system overflowed on one end of the building allowing running water to flood the entire west end of the building causing expensive water damage to offices and inventory as well as a costly clean-up bill. The cause was one of the gutter downspouts had clogged and there was not enough downspouts in place and the overall size of the downspouts were too small. A new and much better design addressing the amount and size of downspouts was the fix in this case.

Roof Drainage

  • Interior Roof Drain – These are very common on flat roof systems. Possible reasons why these fail are original sealants failing along compression of drain bowl ring, Built-Up asphalt roofing membrane deteriorating around roof drain, installed to high to drain, single-ply membranes stretching or shattering around drain bowl, expansion and contraction, cracked drain bowl, or cracked plumbing pipe connecting to the drain bowl itself. This includes overflow roof drain bowls.
  • Scupper Roof Drain – In our opinion this seems to be the most overlooked and hardest roof component for a roofer to waterproof properly. This drain is typically made from a metal box or metal sleeve that slides through a parapet wall and drains into a water collecting box with a downspout attached. These fail when the roofer doesn’t flash the chosen roofing material to the metal box/sleeve properly according to the termination required by the manufacturer. Expansion and Contraction of the parapet wall and the metal box itself are cause of many failures. Another issue is the water running back into the roof at the outside end of the metal box/sleeve. This usually due to poor design. This includes overflow roof scuppers.
  • Metal Gutter – Many Commercial/Industrial roof substrates or insulation systems form a pitch in the roof sending the water to one or two ends of a building. It is common to see a metal gutter trough installed with metal downspouts exhausting the water to the ground. Common failure is seen when the gutter hangers have failed allowing the gutter trough to hang or sag. It is here the water collects and runs over the front and back of the gutter trough leaking into walls of buildings, flooding foundations, and causing soil erosion. Some metal gutter systems where not installed with enough pitch/angle to move the water to downspouts. This causes excessive weight loosening gutter hangers, prematurely rusting the basin of the gutter trough, and rusting joints or unions where 2 sections are joined together.

Now that you know how roof drains and gutters fail feel confident that ICC Roofing has repair solutions and well designed roof drainage systems to solve your pesky water problems. We can repair you existing leaking drain bowl, scupper, or metal gutter. Our crew can add or install new interior drain bowls, retro-fit roof drains, scupper roof drains, overflow roof drains, or metal gutter systems.

We also offer custom designed metal gutter, scupper collector boxes, downspouts, as well as copper gutter options. If you feel there is a need for metal gutter replacement or have a roof drainage problem contact our staff and allow us to assist you in troubleshooting, design, and application.