Settled concrete slab floor? Concrete Jack’s experienced foam jacking and slab jacking crews are slab floor leveling experts and can raise your settled floor for a fraction of the price and almost none of the disruption associated with replacement. Unlike overlays such as self-leveling floor treatments, foam jacking and slab jacking address the cause of floor settlement to help ensure the longest lifetime repair possible. Typical repairs don’t even require the removal of your floor coverings. Slab floor leveling sometimes requires installation of foundation piers and chemical grouting, both of which Concrete Jack performs.
Causes of concrete floor settlement
Settlement of backfill material is the leading cause of concrete interior floor settlement. Floating slabs are the most common type of slab floor in our service area (Mid-Atlantic), and are constructed so that the floor slab can move independently of the surrounding foundation walls. However, because of this floating slabs are particularly vulnerable to settlement because of backfill material consolidation.
An alternative type of slab floor, which is more common in the south, is a turned-down or thickened-edge slab. These settle, too, and our process can address them. Turned-down slab floors requiring repair in the Mid-Atlantic are most commonly found in detached garages.
After your home is built, the rule of thumb is that it takes about 10 years for the soil placed during construction to settle, which removes support from the floor. Floors generally settle slower than the soil because of the friction against adjacent walls, floors and area of adequate support. Sometimes plumbing, particularly sewer lines, can develop bellies and misaligned joints which can cause further problems. We recommend having an independent plumber check your sanitary sewer lines under your floor as part of a floor lifting project.
Signs of slab floor settlement
There are a few typical signs of slab floor settlement:
Floors are supposed to be installed flat. If you feel like you’re going downhill while walking through your home, your floor’s likely settling. If you have to shim under your furniture to make it sit level, the floor has likely settled. However, some slabs are installed with slope intentionally, such as patios and garage floors, so when they are repurposed to finished space, there will typically be a leaning feeling.
When different slabs next to each other settle different amounts, trip hazards can develop at the joints between the slabs. Trip hazards inside of homes are relatively rare in that usually slab floors are monolithic (one big piece) and reinforced. Old homes without reinforced slabs can sometimes develop large cracks with differential settlement (one side is lower than the other).
Cracks in floors
Sometimes cracks indicate settlement, but cracks are a guarantee in almost all concrete, so just because concrete has cracked doesn’t mean that it has settled. Cracks form before settlement, so they can be a good leading indicator of problems below your concrete. Cracks in floor slabs are often hidden by floor coverings, but will reflect through tile.
Basement floor cracks are relatively common. There are a few causes of cracks in concrete, only some of which are related to settlement. If your house has a crack in the basement floor and the concrete on the two sides of the crack is at different heights, that’s a good indicator of settlement. Lots of small, random cracks don’t usually indicate settlement. They’re what’s generally referred to as shrinkage cracks, and are related to the concrete’s hardening process, not settlement. A sloping basement floor accompanied by basement floor cracks is a surer sign of basement floor settlement than a crack or two by themselves.
Gaps under baseboards
Gaps under your baseboards are one of the surest signs of slab floor settlement. Many homes are designed so that the majority of the structure’s
weight rests on the exterior foundation walls, so as the slab starts to settle the floor pulls down from the walls, leaving a gap. Over time, the framed structure of the house will settle down, which can cause gaps under baseboards upstairs in multi-story homes.
As walls settle or are pulled down by settling floors, door frames can twist, causing doors to “rack” or twist, which can bind the door and keep it from opening and closing properly. Slab floor leveling which involves settlement correction (lifting) can easily correct sticking doors.
Cracks at interior openings
Cracks radiating out from the corners of interior doors in buildings with slab floors are almost always attributable to settlement of the slab floor. These types of cracks result from the floor pulling down part of the wall, and the other part of the wall, or the wall covering, staying attached to the ceiling. In most single family slab houses, there aren’t load bearing walls in the center of the home, so walls split easily, as the entire weight of the roof rests on the outside walls.
Slab floor leveling repair methods
Foam jacking is the preferred method for lifting settled slab floors. Foam jacking is a quiet, fast and clean process and most times floor coverings and furnishings can remain in place. We have lifted 800 square foot floors that had dropped more than three inches using just two dime-size holes in less than three hours. In cases where there are exceptionally large voids under floors (more than 16 inches deep), Concrete Jack can install cellular concrete to fill the large voids prior to lifting with high density polyurethane.
Sometimes self-leveling floor treatments are the best option for repairing settlement. We do not install self-leveling floor treatments, but if they are used to correct settlement, we highly recommend void filling under the affected areas to fix the root cause of the problem before installing self-leveling floor treatments. Self-leveling treatments add weight to the floor, which can restart settlement of a floor which has wedged or is held in place over a void by friction with surrounding structures.
Cost of concrete floor leveling repairs
Slab floor leveling using slab jacking or foam jacking typically costs less than half the cost of replacement. Foam jacking minimizes the cost of flooring repairs because the injection holes are small (dime-size) and relatively infrequent. For example, for tiled floors, we can drill holes at the four-way intersections of tiles in the grout lines and then patch the holes with stained concrete close to the color of the grout or tile. For carpeted floors, we can cut back small squares of carpet, or you can roll it back for the work. To see cost comparisons between different methods of slab floor leveling, see this blog post.
Generally, furniture can stay in place during work. Any baseboards or other finishes which have been adjusted to disguise or accommodate the settlement need to be removed prior to lifting.
Concrete Jack offers payment options for most foundation repair projects.