Bowing Wall Repair

There is perhaps no better-known use for carbon fiber strips than fixing bowing walls.

The reasons are simple:

1. It’s a common problem.
2. It holds significant advantages over alternative repair methods.
3. It works really, really well.

As a contractor, it provides the strength and reliability that you need along with the ease of installation that will be appreciated by both you and your clients.

Carbon Fiber Has the Strength Needed to Stabilize Walls

With a tensile strength of 195,000 psi, or more than 45,000 pounds per carbon fiber strap, carbon fiber is, simply, stronger than steel.

It is also lighter and easier to transport and install.

This strength provides it with a 4X safety factor to withstand the force applied on the wall by standard soil.

This is plenty to arrest the inward movement of the wall and allow for the repair of any cracking in the wall.

Advantages of Using Carbon Fiber to Fix Bowing Walls

Aesthetics

One of the biggest advantages of carbon fiber for homeowners is that it solves the problem in a way that doesn’t detract from the basement.

You don’t have I-beams sticking out into the room. You don’t have the large metal plates on the wall that come with tiebacks.

Carbon Fiber strips are applied flush to the wall and can be painted or drywalled over. No loss of space. No poor aesthetics. No constant reminder of their home’s past structural problems.

Ease of Installation

First, the carbon fiber installation is done completely indoors, removing weather variables from the equation.

Second, carbon fiber is much lighter than steel I-beams or even tiebacks. That means less wear and tear on your vehicles and, more importantly, you and your employees.

Finally, unlike tiebacks or wall anchors, no excavations are required and therefore no additional machinery is needed. From a homeowner’s perspective, it also means no landscaping needs to be torn out. From your perspective, this improves safety and reduces your liability as you don’t have to worry about hitting any utility lines running through the yard as you dig.

 

Fewer Callbacks

No contractor likes to be called back to a job because of a repair that didn’t last. The alternative methods of basement wall repair to carbon fiber each have weaknesses that can lead to callbacks, even if the repair itself holds.

With steel I-beams, the wall is only supported at the point where it is most bowed. And for as strong as steel is, it also has a tendency to flex slightly before reaching peak strength. These two factors can lead to enough movements to reopen cracks. And if the cracks reopen, even if the wall is still structurally sound, there is a good chance the homeowner will be looking to you to fix it.

With Tiebacks and Wall Anchors, they only stabilize the wall in the wall in the part with the interior plate. Unlike carbon fiber straps or even I-beams, they don’t provide support for the entire height of the wall. This can lead to cracks and other problems appearing above and below the interior wall plate, which again is likely to spur a callback.

Installation Method for Carbon Fiber on Bowing Walls

1. Carbon Fiber Layout
   Determine the placement of Carbon Fiber Support based on engineer specifications. The typical layout is 48” on center spacing.
2. Surface Preparation
   Grind approximately 1/8” off the block wall to provide clean smooth substrate, removing all pliable coatings on walls and exposing the aggregate. A dustless grinding system is recommended that meets or exceeds OSHA standards.
3. Fill All Cracks
   Seal all cracks in the wall with a non-pliable product and level as needed to provide a clean, smooth surface for the carbon fiber.
4. Prepare the Base Connection
   There are two options for the base connection. In most cases, drill a hole in the floor at the base of the wall at the center of where the carbon fiber will be applied (or, if the floor has been removed, drill the hole directly into the footer). Later in the installation process the bottom of the carbon fiber will be fashioned into a point and secured with the 3" SupportBar to anchor the bottom of the carbon fiber strip. In cases where shearing has already occurred or where there is a serious concern that the wall will shear, drill a hole into the cinder block wall three courses up from the footing. Then insert a rebar support into the hole so that it sits on the footing. When this is done, fill the core of the blocks with grout through the hole that was drilled.
5. Install the Top Connection
   Predrill the sill plate where the carbon fiber strip is to be applied for the insertion of 2” lag bolts. Then install the bracket to the Install the bracket to the sill plate but don’t tighten it. Loop about 12 inches of the carbon fiber strip around the support bar. Feed both ends behind the bracket to lock/anchor the carbon fiber in place. Chemically bond the carbon fiber strip to the wall and bracket with the structural epoxy before tightening the bolts on the top bracket to secure it to the sill plate. This will prevent the carbon fiber from pulling/shearing under pressure.
6. Apply the Structural Epoxy to the Wall
   Apply the epoxy resin onto the wall where carbon fiber is to be installed using vertical mortar joints as a guide.
7. Adhere the Carbon Fiber to the Wall
   After applying a base layer of epoxy resin to the wall, apply the carbon fiber strip to the wall. Apply more resin on top of the carbon fiber, using a trowel to completely saturate the strip
8. Attach the Base Connection
   Fold the bottom 5" of carbon fiber into a point with the folds of the carbon fiber facing out. Fill the predrilled base connection hole halfway with epoxy and insert the folded carbon fiber. Once the carbon fiber is installed, insert the 3" Support Bar making sure it is flush with the slab. If necessary, add epoxy so that the drilled area is filled flush with the surface of the slab.
9. Allow Time to Cure
   The epoxy resin will then need time to cure to solidify the bond between the carbon fiber and the wall.