I'm not sure if the revised plan simply added another floor or if the overall site plan was expanded - will have to check. Either way, I'm trying to figure out what if anything we should be doing to prevent any damage or to ensure that the sediment plan is a good one or that it is being implemented. It seems almost self-evident to me that putting a house that is 9x as big as the one that was there previously (and digging out a basement where one did not exist) is going to impact us. Especially since our properties are separated by a big difference in grade and a 20? year old retaining wall. I don't have a lot of confidence in the flipper/builder - he's a one-man show, not the usual big builders in this area and he has a lot of complaints on record with the county. There have been a series of bizarre things already, and I'm just trying to figure out what if anything we should be doing to protect our own property.

PPF: All materials have a coefficient of linear thermal expansion. Coefficient of linear thermal expansion for concrete is roughly the same as for iron which is why it (rebar) works well with concrete. Expansion/contraction is significant for long linear surfaces such as the large concrete slab with the crack OPs thread. Though there is a much more to material science, especially concrete and types of concrete, hopefully the following excerpt provides an adequate explanation. THERMAL EXPANSION AND CONTRACTION Materials expand or contract when subjected to changes in temperature. Most materials expand when they are heated, and contract when they are cooled. When free to deform, concrete will expand or contract due to fluctuations in temperature. The size of the concrete structure whether it is a bridge, a highway, or a building does not make it immune to the effects of temperature. The expansion and contraction with changes in temperature occur regardless 0of the structure’s cross-sectional area. Concrete expands slightly as temperature rises and contracts as temperature falls. Temperature changes may be caused by environmental conditions or by cement hydration (the exothermic chemical process in which the cement reacts with the water in a mixture of concrete to create the calcium silicate hydrate binder and other compounds). An average value for the coefficient of thermal expansion of concrete is about 10 millionths per degree Celsius (10x10-6/C), although values ranging from 7 to 12 millionths per degree Celsius have been observed. This amounts to a length change of 1.7 centimeters for every 30.5 meters of concrete subjected to a rise or fall of 38 degrees Celsius. Thermal expansion and contraction of concrete varies primarily with aggregate type (shale, limestone, siliceous gravel, granite), cementitious material content, water cement ratio, temperature range, concrete age, and ambient relative humidity. Of these factors, aggregate type has the greatest influence on the expansion and contraction of concrete. Severe problems develop in massive structures where heat cannot be dissipated. Thermal contraction on the concrete’s surface without a corresponding change in its interior temperature will cause a thermal differential and potentially lead to cracking. Temperature changes that result in shortening will crack concrete members that are held in place or restrained by another part of the structure, internal reinforcement or by the ground. Forexample, a long restrained concrete section is allowed to drop in temperature. As the temperature drops, the concrete tends to shorten, but cannot as it is restrained along its base length. This causes the concrete to be stressed, and eventually crack. Joints are the most effective way to control cracking. If a sizable section of concrete is not provided with properly spaced joints to accommodate temperature movement, the concrete will crack in a regular pattern related to the temperature and restraint directory. Control joints are grooved, formed, or sawed into sidewalks, driveways, pavements, floors, and walls so that cracking will occur in these joints rather than in a random manner. Contraction joints provide for movement in the plane of a slab or wall, and induce cracking caused by thermal shrinkage at preselected locations. One of the most economical methods for making a contraction joint is by simply sawing a continuous cut in the top of the slab with a masonry saw.

ok, there where no peers install. Its a post-tensioned structural slab with no peers. I large 1/8 crack development when the framers did their thing. The tensions weren't tightened before the framing was done. Some people say it should have been like 5 days after the pour and before the framing. Dont know if that is why the crack occurred. But it has. I did hire a structural engineer and take grade levels and he has and he will after it had been tighten, which was done today... It is the structural engineer that is says because of the crack or failure in the foundation, he might recommend peers now. before tightening, his measurements showed the center on the garage were the crack occurred as about 3-4 inches lower than the outer right and left edges. So it might be showing signs that the center has fallen. This MAYBE a need for peers for long term stability. That is were things are at now. Just trying to get the best info I can get to know what to do here...

What does your municipality say? What does the structural engineer/soils engineer/geologic engineer say about the idea? Someone has to physically design your foundation based on your specific site conditions. That foundation design has to get the approval of your municipality. A slab on grade must have a foundation perimeter and load points that goes into undisturbed subsoil. A concrete contractor should understand that, even if he is not a structural engineer. Or undisturbed subsoil with approved and inspected compaction material. A concrete slab isn’t an approved and inspected compaction material. Not without core samples proving what is under it, and the compaction of the fill that’s under it, and the depth at which you reach undisturbed soil. It also will complicate the required termiticide treatment required under slabs. Doing all of the work and reports to prove that you can use it may cost you more than demolition and rebuilding. Time is money in that regard. Working around the old parts of a building is what makes remodeling cost more than new construction. The input of a concrete contractor is valuable, but he is limited to a single perspective that revolves only around his job portion. He doesn’t understand the interconnected complexity that goes into making his job “arrive and pour”. There’s a lot more engineering that happens before that happens. And the GC is the one that coordinates all of those moving parts that the concrete contractor does not see. Talk to your municipality.