01-19-2010, 04:07 AM
Interesting I never saw this topic before but I have posted on other similar topics.
I have the opposite reaction from leilaniguy regarding the crack across the property and what would happen to a slab. A slab would be much better equipped to deal with something like that than individual piers. I have stated in the past that the best option to protect against such ground movement would be to build on a slab, just make it a very good slab. The slab might cost twice as much as a "regular" slab. So be it. Do what it takes. Spend what it takes. After you do your entire house, if it settles, will settle as a unit and can be jacked back up as a unit. Pretend you are building a bridge. It baffles me how little effort and resources are typically put into the most important part of the house, the foundation.
All slabs crack to some degree. Unless the steel reinforcement is pre-stressed, the steel is just there to hold the pieces together. It can not be otherwise. Concrete has a very small strain at failure. Steel by comparison has a very large strain at failure and is hardly carrying any load at the amount of deflection that will break the concrete, after which the steel will carry all the load.
Hotcatz's story gets to the point. People are used to doing things a certain way and even builders who have been building houses for years may not really know the theory of something like how different slab designs affect the outcome unless they have personally tried different designs AND gone back to review the results over time. This is not something that many builders have done. They just build the same thin slab over and over.
I am not saying you can't get good results with pier and beam but the old plantation style houses were built that way because it was CHEAP. There are so many of them around because the plantations ran everything and it was the cheapest way they could provide housing, not because it was the most durable system.
I have the opposite reaction from leilaniguy regarding the crack across the property and what would happen to a slab. A slab would be much better equipped to deal with something like that than individual piers. I have stated in the past that the best option to protect against such ground movement would be to build on a slab, just make it a very good slab. The slab might cost twice as much as a "regular" slab. So be it. Do what it takes. Spend what it takes. After you do your entire house, if it settles, will settle as a unit and can be jacked back up as a unit. Pretend you are building a bridge. It baffles me how little effort and resources are typically put into the most important part of the house, the foundation.
All slabs crack to some degree. Unless the steel reinforcement is pre-stressed, the steel is just there to hold the pieces together. It can not be otherwise. Concrete has a very small strain at failure. Steel by comparison has a very large strain at failure and is hardly carrying any load at the amount of deflection that will break the concrete, after which the steel will carry all the load.
Hotcatz's story gets to the point. People are used to doing things a certain way and even builders who have been building houses for years may not really know the theory of something like how different slab designs affect the outcome unless they have personally tried different designs AND gone back to review the results over time. This is not something that many builders have done. They just build the same thin slab over and over.
I am not saying you can't get good results with pier and beam but the old plantation style houses were built that way because it was CHEAP. There are so many of them around because the plantations ran everything and it was the cheapest way they could provide housing, not because it was the most durable system.