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Patio Doors That Make You Weep

image of a patio weep hole; flashing; weeping; weep hole

Several of our clients have experienced water intrusion around sliding glass patio doors.  There is a mixed bag of flashing problems that can cause water intrusion.  Flashing materials, weep holes, and weep ropes are used to drain water that gets behind the masonry.  

In this image, the black material beneath the vertical bricks is the flashing that drains the water out and away from the building.  The weep rope is supposed to help draw water out from behind the masonry to the outside.  This main issue with this picture is that the weep hole looks small and the rope looks pinched.  

Here we can see that a translucent sealant was placed right on top of the flashing.  This sealant prevents the water from moving to the outside and traps it behind the masonry.  The sealant was only present towards this end of the patio door and not the other.  Inside, a lot of moisture was found directly behind this section of the door and not on the other side where the sealant was absent.

At this property some flashing was present but it did not extend far away enough from the masonry.  The flashing should come out and overlap.  In this image, rust is visible between the door frame and the concrete.  This is a good indication that moisture is actively getting into this patio door.

Here, it appears that new mortar was placed to seal up the weep hole.  It may have been confused for just a simple opening. They probably sealed it up trying to prevent water from coming in, not realizing they were preventing water from coming out! Weep holes don’t always contain weep ropes.  A mesh screen can be placed over the weep hole to prevent insects and debris from entering the cavity. No matter what type, they should not be sealed shut.

In all of the properties shown above, there was moisture detected behind the patio doors.  To prevent mold growth you need to address the underlying moisture issue that is causing the dampness.  If there’s moisture surrounding a glass sliding door, it would be wise to check out the exterior of the patio door to determine if there are any anomalies that could cause water intrusion.  

Ian Cull

Ian Cull is a nationally recognized expert in the field of indoor air quality. He is the Chief Science Officer of Indoor Science, a company he started in 2004. He speaks around the world on air quality topics and is a training provider of the Indoor Air Quality Association. Mr. Cull is a Licensed Professional Engineer (PE) and Certified Industrial Hygienist (CIH). His degree is in Environmental Engineering from the University of Illinois - Urbana Champaign. Mr. Cull has developed 50 air quality related courses for the IAQA University and is the author of the book, “Fundamentals of Mold Remediation”. In his words… “Besides being passionate about indoor air quality, I enjoy cycling, music, the Chicago Bulls, and having fun with my three kids.”