I am told we will have the excavation complete by tomorrow. I don't believe it. We look at the plans for the required elevation heights for the dirt, gravel and slab to make sure there is no over excavation. If they dig too deep or wide I will have to order more gravel. More gravel equals more money. Here is the detail for the Superior Wall at the slab. The one thing that jumps out is that there is no footing! One more time no footing.
Superior Wall to Slab detail. This is one of many possible details for this condition. For various reason this was the detailed that best suited are design.
A footing is used to distribute the load from the walls above to the ground. A typical footings may range between 8" - 12" but may become extremely thick and wide due to soils conditions and the weight of the house. Every type of soils has a soil bearing capacity measured as PSF (pounds square foot). Instead of using a concrete footing Superior Walls replaced it with gravel that is 1/2" or smaller. The small gravel size becomes self compacting. Once the strength of the soil is determined by a geologist there is a chart provided by Superior Walls that provides the required depth needed for the gravel.
My soil came in at 2,500 PSF. With a two story house (floors above Superior Walls) we had to have a minimum of 4" of gravel. Calculating our elevations heights for each item I was then able to obtain the amount of gravel needed.
Notice the different types of soils. We still have a foot or two to excavate. Near the top it is mainly a clay type soil which is bad for a foundation. lucky for us at around the 6'-0" depth there is rock.
Gravel is ordered by the ton and each type of gravel has a different weight factor. For example #8 gravel (what I need under Superior Walls) weighs 1.7 tons per cubic yard and #57 gravel (up to 3/4" for the garage and slab) weighs 1.5 tons. After calling a few places I order from Recycled Aggregate for two reason. They were the lowest in cost but also the most professional. The delivery is set for Thursday the 9th.
Almost forgot to mention one important item. Port-o-Potty / Don John arrived today from United Rentals. It is a thing of beauty.