Note: Changing the soil type to something other than Firm Clay (75 kPa, 1570 psf), may result in requiring an engineer to do a soil review of the build site.

Sand or gravel may be classified by means of a picket test in which a 2"x2" picket bevelled at the end 45° to a point is pushed into the soil. Such material is classified as "dense or compact" if a man of average weight cannot push the picket more than 200mm (8") into the soil and "loose" if the picket penetrates 8" or more.

Clay and silt may be classified as "stiff" if it is difficult to indent by thumb pressure, "firm" if it can be indented by moderate thumb pressure, "soft" if it can be easily penetrated by thumb pressure, where this test is carried out on undisturbed soil in the wall of a test pit.

The Max. Supported Area shown to you in the Foundation menu is an estimate of the maximum deck area which a selected pier can support. This area is calculated with the maximum bearing pressure of the soil (which can be changed in the Edit Components tab, under the General Options menu) and the base area of your selected pier so that the pressure which the pier places on the soil does not exceed the soil bearing pressure. Changing the soil type to something other than Firm Clay (75 kPa, 1570 psf), may result in requiring an engineer to do a soil review of the build site.

Since the base of the pier spreads the loading out over the soil, the larger the load is on a pier, the larger the pier's base area must be to keep the same pressure on the soil below. Some factors such as the weight of beams you choose to use and additional loading due to objects such as stairs have not been included in this estimate for the Max. Supported Area. Therefore, this estimate is meant to be a guide and the actual deck area which your chosen pier can support may be slightly lower than what has been estimated. Due to this, and the desire to space piers as evenly as possible throughout the deck, you may see Deck Designer place more piers than initially expected.