Q&A – How do I fix a Leak Under my Parapet Wall?

After identifying the cause of the leak from his parapet wall, this homeowner wanted to know if he could find a solution without replacing the entire balcony floor. 

Harry, a homeowner in Pennsylvania, noticed a leak in his second-floor bedroom ceiling, directly beneath a parapet wall on the balcony above. Struggling to find the root of the problem, he asked: 

Our parapet wall on the 3rd floor balcony is causing water infiltration on the 2nd floor bedroom ceiling directly underneath. We suspect either the TPO cover strip, membrane underlayment, or water barrier across the top of the parapet under the metal coping might be missing, have degraded or have unsealed holes and/or seams. We covered the top of the wall with plastic tarp as a temporary fix and this has stopped the leak. How do we approach the repair process and fix the leak? There is also a bulge under the TPO membrane on the balcony floor. Can the TPO bubble be repaired without a complete tear out/replacement? Do you have any referrals for professional roofers in my area? 

Roofing expert John Kenney from Cotney Consulting Group, offered this in response: 

You are correct. This is a project for a professional roofer. The wood siding and coping will need to be entirely removed so that the wall can be flashed appropriately up and over the membrane and sealed into the existing roof system. The membrane seal at the meat wall panels from the photo is probably suspected of water infiltration and should also be inspected by a professional roofing contractor. 

As long as there is no damage to the substrate below, the water bubble in the roof system should be fixed with a repair. 

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