the one that was used in the 1800's was called a wood grillage. they would chop down trees and it would lay lincoln logs, same principle, make the excavation, and they would lay lincoln logs and build what is called a redwood grillage. fortunately, the termites cannot attack at and it lasts hundreds of years. >> is resistant to decay. >> the second most common foundation, as we move forward, the cement can along. >> all the homes, all the buildings rest on just a typical spread type footing. the spread type flooding takes the load, comes down, and spreads it out over a larger area. that is why it is called spread footing. as the soil types get more and more difficult, we start looking at social foundations that may still be spread. a spread type foundation such as a mac. -- such as a mat. it is a blob of concrete that is the enough so

the grillage up far enough so it would spread out the load. today, one would know when to evaluate a building like this, we say to ourselves, there is no way this building can be standing. the bearing pressures that are being posed on the soil far exceed the strength of the materials present, yet it works. it could be such a phenomenon as arching and other things to keep the building standing. typically, today, we would support this building on pilings. we would support this going down to more confident material. within this is phil, bay mud, shall mud, and then down sand. re tom hill, at one time second street ended at howard. at that point, there was a large hill. the wealthy people of san francisco lived on top of the hill, and churches were built along howard. then the city fathers in the 1920's let us knock down the hill, let us extend second street, and it finishes at the ballpark now. as you move south along second, that whole area, you get into rock. many of these old warehouse buildings, as you approach rincon hill, are sitting on roc