I used a grinder to smooth the foundation walls for rigid foam adhesion. 2x4 walls with unfaced batts were used behind the foam. I had Icynene sprayed around the entire rim joist perimeter area. I caulked and spray foamed all seams and penetrations in the basement. So far, I still have the fiberglass batt insulation in the rear framed wall that's above grade. I'm weighing the cost of other more air tight insulation options for that wall.

We just built a walk out basement and love it! We came from Missouri so we were VERY accustomed to walk outs with the hills, but when we moved to Oklahoma, the land is just to flat. But we found a hill! Most people here have no idea what a walk out basement is until they see a picture. We have very young boys but I am not nervous about having the walk out. The deck is high but really the railing is tall and tight so I have no worries about them falling. I like having a level front yard and level backyard. Our landscaping is simple, we built a boulder retaining wall to hold back the dirt on one side of the house but the other side has a gentle slope so we just graded it off. Most people see the front of your house anyway and it just looks like a normal house. The basement ceiling is over 9ft and with huge windows so it is very bright open and doesn't feel like a basement at all. There is no doubt that we would do a walk out basement again. I love being able to access the backyard from the basement and having a patio and deck is nice. We planned the deck so we could add stairs from the deck to the backyard later if we decide to, but I like how useable the space is without stairs. The energy efficiency of the basement is so much better than a normal 2 story would be and we still get the space without a huge footprint.

A diagonal crack like this is definitely one from differential settlement. As Worth say, notify the contractor in writing (as a future record), and request he excavate the soil in the vicinity of the crack and determine: 1) the depth and extent of the crack; 2) the condition of the soil beneath the foundation in this area to see if it has been properly backfilled and compacted. Continue to monitor this crack, with tape and or permanent weatherproof marks to see if it is moving and/or increasing in width. Good luck with your project.

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.