Corrosion of Hurricane Straps and Metals Embedded in Foundation Systems
A tried and true conventional way to anchor the framing of a house to its concrete foundation is to install an anchor bolt which are simply bolts inserted into the middle of the stem wall edge when the concrete is placed. Certain foundation hardware suppliers came up with what they thought was an alternative approach which was marketed as saving time and expense. Perhaps even saving one day of labor of the building of the house. As a result of this misstep tens of thousands of houses now have severely corroded foundation systems. In warm tropical climates such as the Hawaiian Islands the problem is endemic and more serious as the Island environment is not only conducive to corrosion it is also frequently in the path of major hurricanes. The structural integrity of the houses which is a life safety feature is compromised when needed most.
Mud Sills anchor sometimes called MAS connectors are used instead of the anchor bolts. These anchors are made out of relatively thin galvanized metal and installed inside of the framing. Instead of there being the typical and required two inches of concrete cover required to protect the metal. These connectors sit by design at the edge of the slab coming out at an angle. At the bottom there is two inches of cover and as it angles it up the cover becomes an inch and a half, then an inch and a quarter, then an inch, then ¾, then ½, then ¼ inch and then no cover at all. This thin galvanized metal is not corrosion proof and in reality, not corrosion resistant. Nothing remains to anchor the house to the foundation except for certain hurricane straps as such the house is exposed to damage in a wind storm and rendered essentially not connected in the event of the strong winds of a hurricane.
The metal hardware supplier also developed another product to replace the conventional foundation design for sheer transfer which is the extraordinary loads placed on a house in the event of a wind storm or hurricane. All energy compacted until the roof or the walls is able to be transferred into the foundation or to the adjacent soil. When the hurricane straps corrode, since they are installed, by design, with the same lack of concrete cover allowing the straps to corrode. At the bottom there is two inches of cover and as it angles it up the cover becomes an inch and a half then an inch and a quarter than an inch then ¾ then ½ than ¼ inch and then no cover at all. This thin galvanized metal is not corrosion proof and in reality, not corrosion resistant they are rendered virtually useless again exposing the house to extraordinary damage.
Nothing remains to transfer the wind forces into the foundation and soil leaving the houses not protected by wind storms or hurricanes.
These galvanized pieces of hardware whether mudsill anchors or hurricane straps are all made of relatively inexpensive galvanized metal. Stainless steel was in the product line but apparently not promoted by the manufacturer, as were thicker amounts of galvanization. Litigation of earlier cases suggests evidence that the inherent defect was known while the products were sold. Hurricane straps have routinely found to be corroding in the Hawaiian Islands as well as in California and even Arizona.
The repair is to remove and replace. Restoring the house to its original design integrity. The homeowner is entitled to nothing less.