January, 2020
Inspection News and Views from the American Society of Home Inspectors

The Mysterious Leaking Garage


This leaky garage is tucked into a hill beneath living space and a concrete patio (Photo 1). The home, built about 1945, underwent expansion in 1977 to create more living space atop the patio/garage roof. In 1983, the homeowners added another 1½ inches of concrete over the garage roof in an attempt to stop leaks.

The garage ceiling leaks continued until 2014, when the extra 1½-inch concrete layer was removed. Installed in its place was a waterproof membrane, topped off with a new layer of concrete.

Well, the leaks stopped for a short time, but then they returned in the central area of the garage. Now, every time it rains, water leaks into the garage (Photo 2).

This is no ordinary leak 

Several contractors who looked at the issue didn’t have an answer. Eventually, a basement repair consultant suggested that the owners should ask me to have a look. I reluctantly agreed because I thought it was a simple leak through the garage walls buried below grade. 

But I found something quite different. Heavy water intrusion was occurring near the central support for the garage roof/patio slab, below the 1977 addition. Minor leaks also occurred near the east and west walls, with “stalactites” hanging from the ceiling.

Good conditions for detective work 

The slab over the garage had been pressure-washed before I arrived, and several inches of rain had fallen the previous night, so this was a good time to look for leaks. The slab was in great condition and pitched to the outer edge of the garage with the membrane visible at the edge. There was no ponding water or cracks (Photo 3). 

The wall of the 1977 addition over the garage ceiling/patio slab had newer vinyl shakes and visible metal flashing over the capstone of the adhered masonry veneer.

The mystery has been solved 

The new slab and membrane were placed on the side of the adhered stone (Photo 4). Water drawn into the adhered stone runs down to the original garage roof slab, beneath the new membrane. From there, it spreads on the slab. 

The adhered stone is missing a weep screed and should be spaced about 2 inches above the slab/membrane. The membrane should extend up the wall of the addition, under the stone. The stone wall also needs base flashing. A difficult and expensive repair will be required to rebuild the adhered stone and the membrane over the garage. 

During your inspections, always look for problems with adhered stone. Remember: All siding leaks. 

To learn more, attend Tom’s technical presentations at educational sessions for ASHI chapters. Tom will present “Basement Inspections, Reporting and Identification of Defects” at ASHI InspectionWorld® 2020 in New Orleans. Tom can also provide his knowledge for your educational event; contact him at Tom@HTOYH.com. 

Tom Feiza has been a professional home inspector since 1992 and has a degree in engineering. Through HowToOperateYourHome.com, he provides high-quality marketing materials that help professional home inspectors educate their customers. Copyright © 2019 by Tom Feiza, Mr. Fix-It, Inc. Reproduced with permission.