New Jersey home inspectors should be familiar with the use of carbon fiber straps for horizontal foundation wall reinforcement. While performing home inspections in NJ it is likely that on occasion home inspectors will discover that the foundation walls in the home they are inspecting have horizontal mid wall cracks. Sometimes the walls will actually be bowed inward. It is likely that the horizontal cracking was caused by hydrostatic (water) pressure exerting forces beyond the design capacity of the wall. When such cracking is present it is beneficial for the NJ home inspector to be able to explain some possible repair solutions to their clients.
Hydrostatic pressure is the term used to describe water pressure against a wall. The problem occurs when there is too much ground water collecting around the exterior of a home. When there is too much saturated soil, the soil expands and exerts tremendous pressure. This soil pressure is the mechanism for the foundation wall cracking and in some instances wall movement. Clay soils are more vulnerable to hydrostatic pressure. Soil that has a large amount of clay in it is referred to as expansive soils. The more clay in the soil the more vulnerable the soil is for water retention and the greater force exerted on the foundation walls of a home.
During the home inspection if we as NJ home inspectors view a structural foundation wall crack. It is useful to be able to simply explain the likely cause and a possible solution. One such popular and somewhat cost-effective repair is to install carbon fiber straps along the cracked wall to reinforce the wall.
Carbon fiber straps ae installed to reinforce and help stabilize the cracked and bowed foundation wall. Carbon fiber straps are thin straps made of crystalline filaments of carbon. The fibers are very strong, light and stiff and can be used as structural material because they are so strong. Carbon fiber is also not able to be stretched, that is why this material is so desirable in foundation wall reinforcement. Carbon fiber is used in the construction of aircraft due to its light weight and tough construction. The straps can be used for walls that are bowed inward as much at three inches.
The installation of carbon fiber straps is typically straightforward. An epoxy resin is applied to the wall where the strap is to be installed. The carbon fiber strap is applied to the wall into the resin with an overlap at the top and the bottom. Once in place the carbon fiber Stap is anchored to the sill pate at the top of the wall and anchored to the floor slab at the bottom of the wall. The additional strap material at the top and the bottom of the wall is folded over back onto the strap. Additional resin material is then applied to the strap. The spacing of carbon fiber straps should be about four feet apart. There are some variables however the four feet separation is a good rule of thumb. The cost of carbon fiber straps is roughly $700 per strap installed. It is advantageous to use straps hat are made of a carbon fiber mesh rather than a non-mesh strap. Non mesh straps sometimes do not adhere properly to the foundation wall. Mesh straps have greater adhesion to the foundation wall.
Once installed the straps have a low profile that can be painted. Finished stud walls can also be installed over the straps. Carbon fiber straps are one way to reinforce or stabilize a cracked or bowed foundation wall. As NJ home inspectors we should understand the basics of this method of stabilization and be able to explain the benefits of using these straps to our home inspector customers.