In the third part of our series on the importance of flashing in a home, we move from the roof to other parts of the structure, where this critical tool for preventing water damage is often neglected. Certified inspectors, like those at A-Pro Home Inspection, will report on lack of flashing in key spots, as well as ineffective and broken flashing installations that are not performing their intended function—shedding rainwater or melting snow/ice and preventing it from damaging surrounding material, spurring mold growth, and, worse, penetrating into wall cavities and compromising framing components.
Today we’ll be looking at common problems associated with window flashing and deck ledger board flashing. Here are a few of the issues that have been reported by the inspectors at A-Pro after assessing many thousands of homes over the last 27 years:
Window Flashing: As with any exterior wall penetration, windows are prone to leakage. Like we’ve noted in past articles, following recommended practices is key to installing flashing that will protect the windows and the home for many years. Unfortunately, the job is often left to non-professionals who may cut corners, leaving windows vulnerable to moisture problems that will eventually fall in the lap of unsuspecting homeowners—another reminder why you should never skip the home inspection when buying a property. This holds true whether the flashing is made of galvanized steel, lead, copper, aluminum (not recommended in climates that can cause it to degrade), steel/aluminum alloy, acrylic, or other material.
- On houses with siding, metal drip-cap flashing (also called Z-, J- or L-flashing,) is installed over the top of a window to prevent water penetration (the drip cap’s leading edge is the only window flashing that will be visible to the inspector once the windows have been installed). Some windows come with built-in channels along the top, eliminating the need to have cap flashing installed separately. The lack of cap flashing can lead to water pooling on the top trim and its subsequent decay; seeping into the home; leaking around the window; and even penetration into the middle of double-hung windows.
- Flashing tape is installed along the inside edge of the rough-cut frame to keep water away from the window’s opening.
- Sloped vinyl pan flashing, or “kickout” flashing, fits along the window’s bottom edge to drain water downward.
Additionally, the home’s vapor barrier itself, which is stapled to the inside of the window’s opening before the windows are placed, also serves as a type of flashing.
Failed window flashing and resulting leaks can occur for several reasons, including installers who do not closely adhere to manufacturer guidelines; giving water no means of escape by sealing windows at the bottom; and incorrect or shoddy installation of flashing tape. Your inspector will be able to report on damaged or missing cap flashing (or cap flashing that has not been installed continuously above projected wood trim), but whether flashing tape is hanging loose or has been installed in the wrong sequence behind the exterior cladding or trim will not be observable. However, visible wood rot at horizontal surfaces and evidence of moisture leakage may indicate flashing issues. While most window flashing may be hidden, old and failed sealants around windows that allow moisture penetration will be noted in the home inspection report.
Deck Ledger Board Flashing: Proper flashing of the section at which the deck connects to the home is critical, as deterioration of the band joist or rim board area due to water penetration can lead to deck collapse. This includes back flashing behind the ledger board, plus observable cap flashing that diverts water over the ledger and away from the building.
When the wood becomes water damaged, it may no longer be able to hold bolts and screws, leading to deck failure. Even minor flashing concerns can allow a great deal of water into a deck system, so your inspector will note defective installations and visible damage in the report. Many inspectors will tell you that it is not uncommon to find deck ledger boards with no flashing at all, particularly in communities where builders commonly skip this step, making it a normalized yet dangerous practice. Regardless, your inspector will make note of inadequate or non-existent deck ledger flashing in the report.
In addition, your inspector will check for issues with exterior door flashing, flashing of exterior wall penetrations (vent pipes, HVAC lines, dryer vents, electrical penetrations, condensation lines, et. al.), and porch flashing, which we’ll discuss in a future article.