Should I Use Plate Anchors for Structural Foundation Repairs in South Carolina?Aug 25, 2018
As the premier foundation repair company in Columbia and Charleston, South Carolina, we often work with clients whose foundation wall is damaged by settling or by lateral pressure from swollen soil, which places the entire foundation at risk. Whether the foundation wall is poured concrete that has cracked and begun to rotate inward or concrete block that is bowed or bulging in the center, a damaged wall left unrepaired can disintegrate and collapse. This leaves an entire section of the house unsupported and causes systemic damage throughout the structure.
There are a number of different ways to repair a damaged foundation wall and all are designed to do one thing – stabilize the wall completely to prevent any further movement. One method, plate anchors, has more than a few faults and homeowners should think twice if it is recommended to them as a permanent solution. In this article, we will define plate anchors and discuss the problems associated with them.
What is a Plate Anchor?
A plate anchor is a structural component used mainly in masonry buildings. These plates are connected to a rod or bolt and are typically visible on the outside of the foundation. The anchor plate distributes the tension created by its anchor point and stabilizes the connected wall. These plates are usually decorated or stylized, as they are visible on the outside of the home. In older homes, these plates were made of cast or wrought iron, however, plate anchors are usually made of steel in modern construction. The cast or wrought iron used to make anchor plates before the 20th century were used because both of these materials were easy to work with. Cast iron is brittle and wrought iron bends easily, however. Therefore, neither metal was a perfect material. Modern buildings typically have anchor plates made of steel. High-carbon steel has a very similar appearance to wrought iron and is often used to give an antique look to an anchor plate.
The general construction of an anchor plate is the same, regardless of its actual appearance. These plates are wide and flat—the bigger they are, the wider the distribution area. On residential homes, they are rarely more than 2 feet across; on a commercial or industrial structure, they may be much larger. There is a hole in the center of the plate used for connecting the tie rod or bolt that penetrates the masonry wall. In essence, the anchor plate is nothing more than an oversized washer.
The rod that sits in the middle of the anchor plate penetrates the wall behind it and connects to the inner frame of the building, often hooking directly into the horizontal floor supports. These connectors are placed approximately every 6 feet on the outside of a building and on every floor. Anchor plates are what keeps the outer wall of the building attached to the inner frame.
The outer wall exerts a lot of force on the sunken bolt and, in order to counteract this stress, the anchor plate distributes the weight of that wall section over a larger area. The wall exerts the same force regardless of the size of the plate, so a larger surface area dramatically drops the pressure exerted. Without the plate, the wall would tear itself from the bolt.
In theory, this should work; in practice, the approach has some problems.
What are the Problems Associated with Plate Anchors in South Carolina?
As many contractors know, there are several problems associated with plate anchors, such as:
Disturbed soil. To remain in place and create the proper tension, the buried plate must be in undisturbed soil. If the plate is placed incorrectly, it will move tension on the threaded rod will be lost and the wall will no longer be stabilized. In a modern residential neighborhood, it is difficult to find undisturbed soil as the typical residential area has been built with multiple foundation excavations and extensive grading across multiple home sites. Fill soil has often been trucked in to building sites and tree stumps have been removed, making it less likely that soil has been undisturbed.
Maintenance required. Even if the soil conditions are absolutely perfect, there will still be some movement and loosening of the plate anchor system. This means that the homeowner must maintain the system by periodically tightening the fittings on the inside; failure to do so means that wall movement will resume. This maintenance can be difficult for smaller or older homeowners and any plans to finish the basement space must include access points for each of the multiple plate anchors.
No immediate result. Because of the issues with soil and the required maintenance, it can take much adjustment and tightening of a plate anchor system before the wall is completely stabilized. This can force the homeowner to delay plans to sell or remodel the house. Should the sale or purchase be contingent upon the sale of the home, problems may exist with closing on time.
Repairs are obvious. Even a successful plate anchor job leaves behind much more than a telltale sign – large steel plates bolted to basement walls. This can be at best a red flag and at worst a deal-breaker for a potential buyer. This signals the possibility of continued maintenance to prospective home buyers.
There are several better ways to stabilize a foundation wall and a homeowner with foundation damage should be careful to choose a foundation repair contractor that can recommend the right choice. While plate anchors have been in use for decades, the newer, more versatile methods are worth exploration. The experts at CNT frequently recommend carbon fiber or channel steel repairs to stabilize foundation walls and they do so based on years of experience.
Foundation repair is not a do-it-yourself project nor is it a job for the inexperienced professional. As one of your largest investments, it is wise not to leave repairs to chance. Contact the experts at CNT for a free estimate and allow us to work with your family to protect your asset.