how to build?

[Joe Carrick]

How about a concrete or masonry support wall just a few feet back from the railing. This could be either faced with masonry or stained a dark color to make it appear that it cantilever much further.

But I still think that landscaping will soon hide the cantilever anyway.

[tompapa]

I read that about Falling Water too. I'd like to get the deck thinner than that. There's a fellow on the Fine Home Building website that said this sort of thing is done all the time and that all I would need to do is find the right person to engineer it. The drop off is actually much more dramatic than I'd originally drawn so I'm pretty intent on achieving the totally cantilevered look. (I'm sure I'll be saving my pennies for that). I'm thinking of moving the entire house forward on the ridge thereby creating even more of a dropoff.

These are more realistic views:

[tompapa]

Also, the area immediately surrounding the house is kind of that golden grasslands/oaks/rolling hills look that I don't really want to change with planting. I'm thinking maybe a vineyard sort of thing at the base of the knoll even though I couldn't care less about wine. I just like that organized vineyard look, heh, heh!

[Joe Carrick]

Don't forget to provide a way from that deck down into the surroundings. I build my house on a steep hillside, figuring I'd just leave it natural. Over the years, I've terraced, added patios and decks, even a putting green and driving cage.

If nothing else, you might want to take a stroll in the vineyard

[tompapa]

You can't really see from the views I posted but where the deck railings meet the house there are openings. I don't envision spending much time in a vine area but on the east side of the house I've got plans for a pool and that's going to require some fairly involved stair action. I heard from a friend of mine that I may be able to contract out the vine thing and somebody else does the work in exchange for the grapes. Who knows whether that's true or not but I'm probably too lazy to plant all that stuff myself. I just think all those rows would be nice to look at, lol!

[Drizit]

A good Concrete guy could def figure this out for you...Heck Buddy of mine built a pyramid that was made for a winery with no steel in it...(bad energy i am told ) So yes anything is possible, you could make you center thicker where it is buried and attached to the pillars then make the edge thin so it look all thin....

[RMorrison]

Hi Tom,

I'd seriously consider a concrete floor poured on ribbed metal decking, supported by a steel framework for the cantilevers, using a stucco soffit with maybe a lightweight stone veneer for the walls You COULD use structural concrete for the cantilevers, but I think you'd be in for some long-term heartache.

[Allen42acj]

How about the floor plan with the deck size?That would be fun designing,but not sure if you have to be an engineer to get it approved.
Not that high were people will get killed if it falls..

[RWF]

Have you heard of this stuff for waterproofing?

http://www.kryton.com/support/learning/crystalline.php

I remember reading about it in one of those Architectural Record continuing ed. things. Whole new concept in waterproofing concrete I guess.

Also check out:
http://hoffmannarchitects.com/public...fs/vol23n2.pdf
This seems like a good general article on concrete cracking- not specific to this cantilevered discussion

[ladewa]

Have you talked to an engineer about post tension concrete?

[mbbailey]

I would make the foundation circular and use "L" shaped beams embedded in the foundation that extend to the edge of the deck. They could be spaced at the required interval (4' O.C.) to support the deck. The beams could become part of the deck floor in the process with precast concrete slabs between them. You could cover it all with materials suitable for moisture seal and walking surface. This should last for 50 years easy and an 8' cantilever is not that far out.

[ScottVH]

you can tie back and prevent up lift with helical-piers and do the taper joists to give it the required strength and prevent tipping. (check abchance.com)

[tradewinds63]

It's just a simple PT design...
There's no doubt about this design proposal, it requires post tension engineering. The interior floor system and the deck will be 1 combined post tension slab. The supporting walls will be concrete also. This will not be designed by your regular engineer (not unless he has the proper experience), the post tension company that you select should draft up the appropriate engineering, inclusive of the tendon layout, chair specs, etc, you'll have to keep concrete samples onsite to evaluate the cure prior to tensioning and shoring removal, there are several engineering aspects involved in these systems.
Be advised... it's a very expensive process, so weigh the options carefully. Is it really worth removing a post for such an added expense? Should you be incorporating a parking garage behind the deck... I could see the PT route, but not for a simple residential design.
How about a transparent acrylic post? Wink

[tradewinds63]

There’s one other option and I’ve batted it around since 95, it’s probably cutting edge and would require cooperation with one of the engineered beam manufacturers. Some form of PSL with an imbedded tendon system inside the beam, it can be done, but don’t know if it has been. Drop a request to Weyerhaeuser and see what they say, it would probably end up in some sort of engineering article should they take on the project. It could get somebody a bit of publicity. It will boil down to the grain compression to the required tendon tension and arc.

[tompapa]

Thanks for the additional input everyone. I have found a company that does post tensioning within range of the jobsite and will be contacting them tomorrow. It'll be interesting to hear what they have to say. Including about the cost factor.

Richard, why do you recommend against concrete so strongly? I must admit, I'm intuitively somewhat nervous about using it, (especially after checking out Roy's link, heh, heh), and, on the other hand, I have a lot of confidence in steel. I also recall reading about "creep" and "deflection" with concrete and wasn't too comforted. There are some real advantages to using concrete though, if it is indeed sensible. I'd be interested in knowing your reasoning for not going with it.