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Woe is My Flat Roof

The sloped, asphalt shingle roof is my kind of roof.  Use quality materials, make a professional installation and you can pretty much walk away from that roof for the next twenty years.  Low slope roofs (sometimes erroneously called ‘flat roofs’, as even these roofs must have a tiny amount of pitch to function correctly) do not allow this kind of leisure.  No matter the product used, low slope roofs must be maintained regularly.  In fact, it is fair to say that while the life expectancy of the shingled roof would be proportional to the quality of the materials used and the care of the original installation, the life expectancy of a low slope roof is more directly tied to the amount, quality and consistency of the maintenance provided after installation.

Most experts recommend a semiannual inspection of any low slope roofing system.  For those of us in the Midwest, the best times to do the inspections would be in the spring, after all the snow and ice has melted off the roof and in the fall to ensure that the roof is ready for the next round of winter.  It is also advisable to have the low slope roof inspected by a professional after any kind of severe storm activity.  High winds and hail can compromise your flat roof just the same as they would a pitched roof.

You may want to familiarize yourself with the flat roofs for which you are responsible.  The utmost care must be taken when walking a flat roof.  Something as simple as dropping your keys could severely damage some flat roof applications.  Always remain on the walk pads if your flat roof has them.  Things you should be looking for:

  • Debris collecting on the roof
  • Clogged drains and scuppers
  • Tree branches that may come in contact with the roof
  • Compromised flashings around any roof top penetrations
  • Cracks or penetrations in the membrane
  • Unsecured or corroded perimeter metal
  • Cracked and broken rocks on ballasted roofs

While anyone can make a cursory inspection of a flat roof, only a professional roofing contractor should attempt to make repairs.  If your flat roof is leaking, you need the expertise that only an experienced flat roof contractor can offer.

The biggest danger to any flat roofing system is that of ponding water.  As I alluded to earlier, even ‘flat’ roofs should have a very slight taper to remove accumulated water.  If water collects on your roof and doesn’t drain away on its own within 48 hours, a siphon or pump system should be used to get it off.  No roof system is designed to have a volume of water sit on it for any extended period of time. 

Another important thing to take into consideration; water that enters a low slope system gets trapped there and does much more damage than it would in a pitched system.  If your low slope roof is compromised, the longer you wait to make repairs, the more expensive that next replacement becomes.  Just this week we had a subcontractor bid a low slope roof for us.  Trapped water had completely ruined the insulation and decking underneath the membrane.  This professional flat-roofer said if they had gotten to the roof a couple years sooner the bid would have been half as much. 

The diversity of low slope roofing products prevents me from making any more specific recommendations.  You need to work with your roofing contractor to design a program for your flat roof maintenance based on your unique situation.