Roof Defects: Ponding

Home Inspector with Acuity Home Inspections IL LIC. 450.03340

One of the things that I look for when inspecting flat roofs is evidence of ponding.

"Ponding" is a word we use to describe the phenomena of water that remains on the roof 48 hours after it has rained.


Roofs should shed water quickly. The longer water stays up there, the greater a chance it has of finding a way into the house.

It's possible to see signs of ponding on a completely dry roof. Keep an eye out for areas of dry silt -  like little dry lakes. In extreme cases, ponding can support the growth of small plants and even saplings. The presence of vegetation growing into the roof sheathing is a sign of a troubled roof.

According to Carson Dunlop's Home Reference Book, ponding water can decrease the lifespan of some flat roofs by as much as fifty percent.

Correcting the drainage slope of the roof often means a roof replacement. If the roof's in good condition at the time of inspection, free of leaks, with good flashing and good seams,  no further action is warranted. When replacement becomes necessary, the slope issues should be addressed to prevent the recurrence of ponding.


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Debbie Gartner
The Flooring Girl - White Plains, NY
The Flooring Girl & Blog Stylist -Dynamo Marketers

Oh yes, that can be a problem.  I don't think we have many flat roofs here.  That seems like it would be an issue with the snow, too.

Nov 13, 2013 05:30 PM #1
Clint Mckie
Desert Sun Home, commercial Inspections - Carlsbad, NM
Desert Sun Home, Comm. Inspection 1-575-706-5586

Hi Tom,

That's not ponding that's a lake. Man O man that's a lot of extra weight on the roof.

Have a great day in Chicago.

Best, Clint McKie

Nov 13, 2013 10:11 PM #2
Fred Hernden, CMI
Superior Home Inspections - Greater Albuquerque Area - Albuquerque, NM
Albuquerque area Master Inspector

I'm with Clint... let's go swimming! They didn't tell you they had a rooftop pool... did they?

Nov 13, 2013 11:23 PM #3
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Tom Jansson

Chicago Area Home Inspector - InterNACHI Certified
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