Concrete floor slabs in garage or basement areas of your home can become cracked or settle as a result of poor soil compaction. The concrete floor slab, whether in a basement or garage, can experience cracking for several reasons. Most often, the concrete floor slabs are poured late in the construction phase of a project allowing for utilities to be installed and final grades to be established. In covered areas like garages and basements, the soil is dry and does not compact well. When the concrete mason returns to a job to pour the concrete floor slabs, the soil gets leveled out and the concrete is poured. If the soil is not thoroughly soaked with water after its been graded in a slab area any compaction that follows is a wasted effort. Many contractors will run hoses on the areas to receive concrete slabs days before the concrete mason is scheduled to allow for compaction prior to the grading. Welded wire mesh and Polyethylene plastic sheet, 6 mil or greater in thickness, is required on most detailed foundation plans but is seldom installed, and it is also very difficult to verify after the slab has been poured. A foundation concrete floor slab plan that requires a Polyethylene plastic sheet, 6 mil or greater in thickness, to be installed is done so that it provides a vapor barrier. This vapor barrier helps reduce or eliminate water vapor emissions into the garage or basement area of the home and thus creates a more enjoyable and useable space. Some of the areas that are most prone to concrete slab settlement are garage floors and this is because as mentioned earlier, if the soil is dry graded prior to the pouring of the slab and allows for a pocket to develop under the slab, the weight of a vehicle will stress the slab resulting in a crack. Another area that is prone to settlement of the concrete floor slab is the transition areas between crawlspace to full foundation. This step up in elevation means that was an internal overcut and this area can have a minimum 3' to 4' fill between finished floor heights and if not properly compacted this can allow for future settling of the slabs. There are many cases where all the proper precautions have been taken during the course of construction and a concrete floor slab has been stressed due to hydrostatic pressure. A good example of this is homes that are built near bodies of water, tidal or otherwise. Mecox Bay, for example, has an enormous watershed area that covers from Southampton, Water Mill and Bridgehampton. This produces spikes in the watertable that can range from several inches to several feet. If a concrete floor slab is built according to design with welded wire mesh over a Polyethylene plastic sheet, 6 mil or greater in thickness, on compacted sand, it will lift from this spike in the groundwater table and in some cases need to be replaced. Depending on the amount of hydrostatic pressure, results can vary from simple cracking to complete slab displacement where the floor will actually lift up on itself. Many homes in these areas have sumps or basins that allow free movement of the groundwater to rise up without exerting pressure or greatly limiting the impact on the concrete floor slab. Every concrete floor slab that has had settlement issues can be addressed in one form or another to repair the condition. Some are easier to live with than others. Slab issues in a garage area can be hazardous and annoying because you’re more likely to utilize that area over the basement on a regular basis. In the case where a floor slab is experiencing signs of moisture or water presence through cracks or because lack of a vapor barrier, there are various techniques that we offer to correct these issues. Please call to schedule an appointment to review your concrete floor slab and discuss the different solutions available.