how to build?

[RMorrison]

Tom,

Yes, creep (and its related cracking) is a big issue, and one which continues over a long period of time. Large, heavy pieces of concrete need to be detailed very carefully for thermal expansion and seismic movement. (Think of expansion joints on bridges.) This can be quite problematic related to water intrusion if it's over any living space. Bridging from interior to exterior space is a detailing nightmare, especially if you are considering thermal bridging. Seismic bracing of a very heavy cantilever can also be a challenge. Then you've got the extensive formwork required if you aren't using precast units -- very expensive to cast concrete in mid-air.

It's all doable, though, with enough money, time, and detailing research. But not a job I'd want to take on myself.

[sutcac]

Thanks for the link to that article Roy, very informative.

Reminds me of when I visited FLW's unity temple about 5 or 6 years ago (part of a little solo FLW pilgrimage). Parts of it looked like that cover photo.

Yeah, I think you're biting off quite a bit on this one. I wouldn't want to take it on either.

[tradewinds63]

I’m seeing the largest hurtle within the proposal as the deck corner… the rest is basic PT.
Would be nice if the Engineer you find goes by the name “Scott” and happens to have a formula for transparent aluminum also…

[tompapa]

Thanks again for the advice everyone. It turns out that your typical cost on a post tensioned slab, say 10" to 12" thick, on the ground, including preparation of the subsurface, formwork, and concrete is around $12/ft. My job will be different as I'll only use their guys for the placement of the tendons and the tensioning but all the issues surrounding the use of concrete lead me to think I'd best take a good look at the steel option.

I guess in the end I'm probably dumb enough and bullheaded enough to attempt this so we'll see how it goes, lol!

[RMorrison]

I guess in the end I'm probably dumb enough and bullheaded enough to attempt this so we'll see how it goes, lol!

Tom,
I would certainly take exception to the "dumb enough" part.

[ErrolVetter]

Very simple in context, however, very complicated in reality. Design of the structure is simple enough, the complications come when calculations have to be made for differential settlement issues between the main and cantilever structures. It would be wise to consult a geotech experienced in this type of structure.
A soils report would have to be done to evaluate the load bearing as well as the passive resistance of the soil. The next problem that will arise is how to control erosion. What effect will live loads have on the structure (e.g., on the cantilever deck) in relation to the passive resistance of the soil? What will the settlement of the main structure be as compared to the settlement of the cantilevered structure (the cantilever structure will exhibit lateral settlement as well as vertical)? What effect will lateral loads have on the structure and soil relation? These are just some of the issues that will have to be considered.

[Tim O'Donnell]

I looked at my book on Falling Water. It's got a lot of detail (Plans, Sections, etc) and those decks are actually made up of a series of concrete beams about 24" deep with a 6" concrete slab. The beams appear to be about 3'-4' on center and vary depending on location and direction from 12" to 30" in width. The railing around the edge is obviously about 36" high and 6"-8" in thickness.

So what looks like a 42" overall height (railing from top to bottom) is in fact at least 60". In looking at the picture you posted, I notice that the deck doesn't appear to be more than about 36" above grade at the corners and almost nothing at the center and at the points where it abuts the house. I also notice that you are not showing any landscaping which would probably hide the cantilever anyway.

Falling Water was/is a sculpture as much as anything, and created more drama for an already dramatic site.

My question in this case, is if the cost and trouble are going to be worth it for your project. Frankly, I think that the drama of the horizontal deck of your project will result from the top edge of the railing superimposed against the house and the landscape. Maybe what we need here is a design critique and cost/benefit analysis.

remember they just spent years and millions of $$$ to keep Falling Water from falling in the water....
http://www.ianosbackfill.com/2003/12...g_water_r.html

[tompapa]

I've been wondering about all that stuff Errol. I figured my next step in the process would be finding a soils engineer. Just out of curiousity, would a boring for the well, which is in the immediate vicinity of the building site suffice for the soils report? The well driller made a report of what he found along the way to the depth of 120'. Or do the engineers require multiple samples or even that they are there to observe?

I'm thinking I'll be taking Richard's advice on the steel and I've drawn up my initial thoughts on how that might look. The fellow who does structural steel for me recommended an engineer who's savy with steel so I'm sure he'll have the final say as to how to go about all this. There is one question I'm also very curious about though. How would you build a deck on I-beams with a pan and a poured concrete slab that would not require more than a minimal step down from the interior of the building? I assume the building would have to have some sort of very shallow floor joist system and it'd be nice to frame the interior floors on top of the I-beams, keeping the construction process simple. Are there alternative joist options other than say 2x6's for this sort of application? Do they make I-joists that small?

Also, is the drawing I've posted the sort of layout you might see for the steel? I'm figuring on some sort of pier and grade beam type situation for the foundation. Just trying to get a semi-sortof handle on the cost here. If I have an idea what the end result is going to look like figuring materials is relatively easy and I already know what I'm going to charge myself for doing the work, heh, heh!