The part of town I live in got hit hard. The shops and restaraunts flooded. The streets, plus the cars parked in the streets, got flooded. The houses, most of them built before 1930, for the most part, did not flood. The floors of these houses are above ground, plus they are on an elevated mounds of ground. The houses built after 1950 or so are on concrete slabs, in many cases almost level with the street. The more modern houses have mounds of rugs and appliances in the front yard. The houses built in the last 5 years are still built this way.
I know well this ain’t just Houston.
Why the archetecual change? Was it fashion? Cost? What?
Seems to me the old school archetect’s knew better.
I would say, the difference is FEMA, a relatively new give away, you get flooded, hurricaned, no problem, we’ll build you a new home. Right here where you lost your home recently.
The older homes with the raised floors use what is called a pier and beam foundation. It uses a bunch of piers driven into the ground. The house is built on them. The disadvantage is that with time, the piers shift/sink. This puts a lot of stress on the house frame as it tries to bend to match the piers.
Newer homes use a concrete slab as the foundation. This is an attempt to spread the load of the house evenly across the ground. The slab can shift as the ground moves, without affecting the house frame. As the ground shifts it does put bending loads on the slab. If they are high enough, the slab can crack. Then the house frame is stressed.
A cracked slab is expensive to repair compared to re-leveling a pier and beam foundation.
For small ground movements, a slab foundation is better since it keeps the bending loads off of the house frame.
Stupidity. That’s a crass answer, I know, but there’s some basis for this. In Florida, after one of the hurricane’s hit, all the homes in the ritzy part of one city were wiped out, while in the poor section all the Habitat For Humanity homes were mostly intact. The reason? The Habitat homes had a few more nails in them!
Seriously, generally, what happens is the architect doesn’t think about hurricanes, or whatever, unless forced to by law. I remember seeing one special on an architect who’d “rediscovered” how to build nearly hurricane proof houses. What he did was go look at the old houses which were still standing and had survived several hurricanes and see what enabled them to survive. IIRC, it was mainly how the houses were set on the foundation that enabled the house to survive.
Then there was the program I saw on the Citicorp building in New York. It was designed with all the latest ideas in engineering, etc., followed all the laws about being able to survive high winds, and so on. Then, one of the students of the designer asked him what would happen if the winds hit the building from a different angle than it was thought would happen. (Building codes in NYC specified that the building be able to withstand high winds from a hurricane hitting the building square on, and the student asked what would happen if the winds hit it at an angle.) The designer did some checking and discovered that the building could survive under those conditions. The worry was, though, that the contractor had done some things different than what was called for in the blue prints to cut costs. The designer realized that this made the building very vulnerable to high winds, and they had to get the contractor to correct this. What was worse, was that there was a hurricane headed towards New York, so they had to race to complete the modifications before the hurricane hit. They got lucky, and the hurricane never came close to NYC, so they had plenty of time to get the job done.
The housing industry isn’t unique in this regard, either. Nearly every kind of thing you can think of has been poorly engineered by someone for what seems like a good idea to the designer, but when you get the item into the real world, you have to wonder what in the hell they were thinking.
A slab foundation is cheap, much cheaper than pier and beam. As an example, my brother had to build about 400-600 square feet of his house on piers, which cost him about $8,000 more than if he could have used a slab (these numbers may be quite a bit off–we talked about this years ago.)
Pier and beam homes may have to be several feet off the ground to meet code, but most building codes only require that the floors of slab homes have to be 6-8 inches above the surrounding earth and that the dirt has to slope away from the slab. You can mound the dirt so that the floor is well above the surrounding grade, but homebuyers don’t seem interested in paying extra for dirt.
The United States in general underwent a house building boom in the 1950’s. Houston, in particular, exceeded the national house building rate. My guess is that from 1950 on, the emphasis has been on getting houses up as quickly and cheaply as possible and the quality of the finished product is no longer a priority.