Your home’s exterior finish is its face to the world. First and foremost you want it to look attractive and reflect your tastes. If you’re like most Americans, you also want it to last for many years with minimal cost and maintenance. In fact, the promise of low-maintenance exteriors has driven much of the development of siding materials over the past few decades. “Vinyl is final,” was the watchword of a generation of siding salesmen.
Yet despite many advances in building materials, water damage to building exteriors and the structure beneath has increased dramatically. Water leakage through building exteriors has become a leading cause of callbacks across the United States.
In most cases, the moisture problems were not caused by a single material, but from the exterior system as a whole. Even with the best siding materials, improper installed flashings and weather barriers are often at fault. Add to that modern wall systems that trap water for extended periods and you have a prescription for serious problems.
Most of these leaks occur around window and door openings other joints and other penetrations in the building shell — for example, where a roof or cantilevered deck meets an exterior wall. In some cases, caulks and sealants delay leakage at these poorly designed joints for a few years. But most caulk joints fail over time, allowing water to enter.
All Exteriors Leak
While wood siding, brick, vinyl, and other exterior finishes may appear watertight, in fact, all residential “cladding” systems allow some water to penetrate. This is especially true during wind-driven rain when high air pressure forces water to flow through small openings at siding joints, overlaps, nail holes, and other gaps. read more
The best way to protect the structure, siding, and paint or stain from moisture damage is to design the outer layer of the house as a decorative “rain screen”. A rain screen should be sturdy enough to block most of the wind and rain, but porous enough to dry to the exterior when wet. read more
Windows are most common source of water leaks in new construction. The challenge is how to integrate the flanges found on most windows today with house wraps and other water barriers. Careful detailing here is critical to success. read more
Referred to in the building code as a “water-resistive barrier,” the main goal of a sheathing wrap is to keep liquid water out of the structural part of a building. At the same time, the sheathing wrap must allow water vapor to pass through so the framing and sheathing can dry to the exterior if gets wet. read more
Flashing membranes are now widely used to prevent water leakage around windows and doors and other trouble spots on walls. Sold as flashing tape, flexible flashing, and peel-and-stick window flashing, these narrow rolls of membrane can solve many flashing problems if installed correctly. read more
The thin aluminum flashing widely used today is inexpensive, but is a poor choice in many applications. Always choose metal flashings that are compatible with the adjoining building materials and are at least as durable as the siding or roofing materials where they are to be placed. read more
Wall Flashing Details
Properly installed wall flashing is critical to your building’s health. Many people believe that inadequate vapor barriers are the main cause of moisture problems and wood decay in walls. However, the vast majority of water problems in walls are caused by water leakage from the exterior. read more