Mudjacking is the method used to raise sunken or un-level concrete slabs. The process is typically utilized on exterior members such as driveways, sidewalks, porches, etc. It can be done on an interior concrete slab on grade but will typically result in collateral damage to interior partitions, ceilings and drywall. An 1-3/8” diameter hole is drilled through the slab and mud is hydraulically pumped under the slab through the hole creating lift.
This is a process in which steel (rebar) is added to a slab that either does not have or has inadequate steel and is exhibiting movement due to soils either expanding or settling. Typical applications are in a fractured interior floor slab in a home. If expansive soils under a home become hydrated, they can swell causing the interior slab to heave. Usually the movement occurs at construction joints but can cause new fractures in the concrete slab as well. Rebar stitches are installed at the point of fracture. They are installed at 18” O.C. They are typically 3’ long and are set around the middle of the slab (around 2” deep). The bond the two separated slabs back together creating a bigger, heavier slab that is harder to move if additional movement occurs in the future and they add flexural strength to the slab. Stitching is a very effective way to deal with common soil movement issues in structures
Stem wall Repairs
The stem wall is the portion of the foundation that sits on the footing and sticks up out of the ground by a minimum of 6”. The exterior walls of the structure are built directly on top of the stem wall. They are typically constructed the same width as the exterior wall. A 2x4 exterior wall sits on a 4” wide stem wall. Code says they should be typically 18” from the top of footing to the top of the stem. They have rebar running both vertically out of the footing and horizontally along the length of the wall. We find that there are usually only one horizontal run but we have run into multiple runs. Structural repairs become necessary when the rebar within the structure begins to corrode causing fractures in the stem wall. A typical indication is when a horizontal fracture in the stem becomes apparent. The repair method entails demo’ing the concrete all the way back to behind the rebar and to sound concrete. Once the rebar is exposed, it is either repaired or replaced. If the mass of the rebar has lost 20% or more of it’s original diameter it is replaced. Otherwise, it is cleaned of all rust and corrosion. Prior to patching, all concrete and steel surfaces are primed with epoxy to create a better bond and to help protect the steel surfaces from corrosion in the future. The sections of repair occur at 3’ intervals so as not to knock the feet out from under the structure.