Lisa from Middleburg writes:

"I have a balcony over part of my living room, and the floor of the balcony is a rubber roof. Water stains seem to be forming on the living room ceiling, and I think there is water coming in through the balcony door, but it's hard to tell. Is there anything I can do to diagnose this?"

It's fairly impossible for me to diagnose without seeing it, even with photos.

But, if you want me to take a try…

Rotted wood is a sure sign water's getting in. If there's soft siding, pull some off to see if you can take a peek at the flashing detail. A properly lapped pan should be beneath the door, metal flashing that goes up behind the siding is common, with a 6" wide rubber batten tape covering the connection between the EPDM rubber membrane and the flashing metal. Occasionally, a roofer will run the EPDM right up the wall and leave out the metal. This flashing detail is ok, as long as the membrane wasn't over stretched allowing movement and possibly pulling away from the wall. Also, look for an over reliance on caulk instead of a good flashing detail. There are a number of possible flashing details. I've just described 2, but there are many ways to skin a cat, as they say. Look for a loose bond between materials or possibly no intelligent flashing detail at all and just gobs of sealer.

Occasionally, furniture that rests directly on the membrane, which I recommend against. There could be a pin hole causing a leak. Also, whatever water collection system (gutter or "scupper") is being used could be blocked, allowing water to build up too high in some places. Keep in mind that water is extremely difficult to track. The infiltration point could be nearly anywhere and traveling by imperceptible paths a fair distance.

The only sure way to diagnose is to take things apart, look at the details, trace water stains, etc. The good news is: once the water infiltration point is determined, repairing an EPDM rubber roof is fairly easily done with "batten tape" and rubber edge caulk, available from a roof supplier.

Phil Bzdyk, a long time resident of Loudoun County, and owner of Apple House Carpentry, will gladly answer your home remodeling questions. Certified as a Green Builder and Aging-in-Place Specialist, Phil keeps current with new industry advances and technologies. Please email your questions to us at: questions@applehousecarpentry.com