Concrete buildings, water, floods Q.

I have a question. We've all seen and heard the stories about wooden houses being lifted off their foundations byu flood waters.
What I'm wondering is this. Are houses/other buildings of concrete construction (block, o\\poured, whatever) part of the foundation? IOW, are the outer walls "fused" so to speak to the concrete foundation, and as such, how water-tight are they, or how water-tight *could* they be...?
What I'm wonderin is whether it's possible to pour walls and foundation to be one unit, or even, if the foundation could be poured such tat it would come partway up and the framing would go inside of it, and then the exterior sheathing etc. would go on top or perhaps even over it...?
Just how water-tight could a place be made?
Links would be great, as well as any info or thoughts on htis. I'm just trying to think whetehr there are better ways of coping with flooding, than having stick-houses that jsut sort of sit on top of a concrete pad. IT seems like ther ehas got to be a better way, so I'm jsut wondering.
Thanks In Advance!
- K.
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In some places, even full concrete buildings won't save them, such as New Orleans. I found this image interesting:
http://en.wikipedia.org/wiki/Image:New_Orleans_Levee_System.svg
Normally, anchors are embedded into the concrete slab when it is poured, and these anchors are used to attach stick built walls. In a pure concrete building, it is basically like one monolithic structure, if we are referring to cast in place, or similarly concrete block. The slab and/or footings are poured first, and let dry, with rebar coming out where the concrete walls will be. With concrete blocks, the blocks are formed as a wall with the rebar coming through the middle, and then the middle cavities are filled to form more or less a monolithic structure. Large buildings such as my old architecture building, are poured in layers, beginning with the foundation, all the usual rebar goes through the structure, but the forms are attached directly to the concrete for the next layer and then the attachments are cut off (in the case of our building you could see a pattern of metal rebar looking pieces on the exterior walls where the forms were attached). Each layer is poured onto the next, and these basically fuse to the one below it to make one giant monolithic structure. But as far as I know, concrete is porous and not very water tight. I don't know too much about water and concrete personally so I'll leave that to others.
--
Edgar



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Well, that is a more extreme situation than I'm thinking of. I'm wondering whether somethign could be at all water-resistant, and to what extent. TO whit, if, say, 4 inches of water built up on a property, is there a structure that could resist that. Well, aside from building high ;) I'm not talking about serious flood plains, such as South-East Houston...

Well, it sound like a *sturdy* structure would result, which isn't a bad thing. Porosity - hmmm. I have to think about that - although it makes me wonder why dams don;t leak like seives...?
I've just been looking at all the flood reports this week (well, all Summer, actually) and this question popped into my mind.
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3,000# Concrete is not watertight. 4,000# is much more watertight, but all joints must be designed to include waterstops (6" wide ribbed vinyl or rubber sheets) that must be lapped and heatsealed at the laps. An interesting concrete system is Royal Building Systems from Canada, with pvc forms that remain in place and form an impervious surface on both sides. system is set up by sliding the plastic units together and installing rebar as you go. I have a large carwash, detailing, and lube building going up this summer. If your building is not heavy enough to stay put during flooding, a thicker slab will hold it down. I've seen up to 11' thick slabs, and commonly are 3' in areas with high water tables. Underground fuel tanks usually have to have a slab to hold them down. EDS
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In a previous post EDS wrote...

Better yet is to use an integral waterproofer put in the mix. However, any openings (windows and doors) will render the waterproof concrete moot.
It is simply not possible to build a waterproof house unless you design it as a boat that will float when the water gets too high. This is the only idea I've seen recently that has any merit.
--
Bob Morrison, PE, SE
R L Morrison Engineering Co
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Bob Morrison wrote:

Plenty of historic examples. For example, Baltimore has numerous four level brick 19th c. rowhouses on floating foundations that have led to interesting settlement issues
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I've always wondered about a house on pylons that are attached in such a way as to be able to ride up and down on them. Then you just design the house like a boat that will rise and fall with the flood. Would the pylons that are pushed down deep enough survive a flood? Since the house is not actually being supported on the pylons directly, what would the foundation be? Then you have all the plumbing and electrical stuff to deal with. Maybe if they are designed with break away points at certain places near the ground so when it lifts, everything breaks off cleanly at a place that is expected and could be repaired. I thought it would be an interesting study.
--
Edgar



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Isn't there a small neighborhood in the Netherlands that is doing that, building houses that will float in a flood? I saw something on one of those TV specials that mentioned this. I thought it was an interesting idea.
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In a previous post Kris Krieger wrote...

Damn near impossible to make a building watertight as long as it has windows and doors.
FEMA has published a couple of pamphlets on "waterproof" design, but they are a joke. (as you might expect from FEMA).
You can make a building "Flood-resistant", but it would not be a house I would care to live in. The only real answer is build above the flood plain.
--
Bob Morrison, PE, SE
R L Morrison Engineering Co
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Bob Morrison wrote:

Heh, spent a little bit of time recently at a flood plain conference. Some of the T shirtswere amusing:
"Drove my Chevy to the Levee and the Levee was Gone"
I can't remember how it was worded but there was one saying, essentially that you wouldn't build yur house on the median strip of a highway so why build on a flood plain?
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Is that in part because you need to make room for expansion and contraction? ((This prob sounds like a stupid Q., but I don't know and i'm trying to think of some way to discourage water incursion. OK, the obvious way would be to not build in floodplains, and also, to build houses on "mounds" just in case of a "freak flood".))
At any rate, thanks for the following description -= it's very interesting - is this similar to how earthquake-resistant places aer built? I recall having seen, at a Home Show back in California, a seciot of "cinder-block" wall showing them all tied together using rebar.

Oh! That's tuight! Well, sorry for my "duuuuuh" moment there ;)

Hmmm, that *is* a point...

Well, that's intereting. Waterproof to a height of 8' - I'm guessing that you had to have stairs going up to the door(s), and then dopwn into the lower level...? Or was there a way to make the door(s) sealable...?
I'd be very interested in seeing a photo, if you have a link.
Thanks for the info -
- K.
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So doors/windows can actually be waterproofed...? THat's interesting.
Not that I'm planning to live in a floodplain, but given the seemingly- endless flooding that's occurred this year in so many areas, it seems to me that the whole waterproofing concept should be getting more attention. Or is it just too prohibitively expensive? OTOH I suppose even taht is a moot question, since it's prob a lot like the question of quality - i.e., smaller but better quality versus humongous but cheesy. ((I know multi- millionares can afford humongous and quality, but I'm thinking of more average people.))
I looked at the pic, not much visible. I googled it but no additional pics. I was just curious ;)

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