Water intrusion through cracked or deteriorated Stone mortar allows moisture to penetrate the wall cavity. This moisture causes steel ties, also known as wall ties, to rust, expand, and ultimately fail. The resulting corrosion disrupts the connection between the veneer and the structural frame, which can lead to bowing, bulging, or separating brick walls. When water seeps into window sealants or brick cracks, it creates a "vicious cycle" of damage for wall ties that can lead to catastrophic structural failure.
The primary ways wall ties are harmed include:
- Wall ties, especially older mild steel versions, corrode when exposed to moisture trapped in the wall cavity. Ingress through window seals and cracks directs water directly into the bed joints where these ties are anchored.
- As ties rust, they expand in thickness—sometimes to several times their original size. This expansion exerts massive upward pressure, lifting the mortar beds and causing horizontal cracks.
- The cracking caused by tie expansion allows even more rainwater to reach the remaining metal, drastically speeding up the rate of further corrosion.
- Corroded ties lose their "section" (metal thickness) and eventually their ability to hold the outer brick veneer to the building's inner frame. This can lead to bulging walls or a sudden, complete collapse of the outer brick skin during high winds.
Early Signs of Harm
- Horizontal Cracking: Fine cracks in mortar joints, particularly near windows where there is less weight to hold the bricks down, often indicate ties are expanding underneath.
- Wall Bulging: If the ties have failed or detached due to rust, the outer masonry layer may begin to bow outward.
- answer. Make sure that all sealant around each window is fully applied with a backer rod and that any cracks in the exterior stone walls of your house are repaired.
