how to build?

[sutcac]

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.

[tompapa]

You are cantilevereing a super long distance for a very low rise. Put the posts in. You won't even see them. And you won't end up building FallingDown 2...[/QUOTE]

I'll see em'. No chance I'm going to put in posts. By the way, this is a more accurate rendering of the topography. I matched it up with a background shot I took of the site.

I also found some guys in Santa Rosa that do post tensioning.

[tompapa]

[QUOTE=sutcac]Have you heard of this stuff for waterproofing?

That's what xypex is all about. The problem with it, as I see it, is that it works great if the concrete doesn't crack at all. Otherwise water can still seep in so I'm thinking I've got to do a membrane over the deck anyway on account of I've never seen concrete not crack at all.

[tompapa]

Hey Sutcac, I was just reading your link and apparently they're claiming that when cracks happen, (which is inevitable), the water proofing continues to interact with any water that gets in there thereby growing a crystalline structure that prevents future penetration. That goes against what I read elsewhere about hairline cracks and such. I'm going to have to look into this further. Xypex was my original thought for eliminating the waterproofing problem.

[sutcac]

That's funny, I was just reading through the stuff on both sites, and went to reply only to find you had already looked at that.

It seems like this could be what you are looking for. Membranes have their issues too and would ruin the "honest" concrete look it sounds like you are after.

It sounds like you can not only use it in the concrete mix, but could even apply it again later if other cracks develop. But with structural concrete of this nature, your cracking should be pretty superficial. This isn't going to be some 4" porch slab over expansive soils.

Good luck, would love to see the finished photos!

[tompapa]

I've actually used xypex before. Richard Morrison specified it on a house I built. The use was for a basement slab and walls. It's pretty expensive and according to the folks who supplied it you normally add it to the wall mix but roll it on the floor where it just seeps in and makes a barrier of the top layer. Since there was a membrane surrounding the whole basement envelope I think what the xypex mostly did, (and is currently doing), is preventing moisture still in the slab from being wicked up into the hardwood floors. They say this can be a problem for thirty years or more. Actually, I think that process has more to do with condensation and pressure differences than anything. I'd have to reread all that. I've poured some pretty thick structural slabs with a lot of steel in them and you're correct, those don't crack, except for hairline ones. According to the one site I was reading these are a problem for this chemical crystallization stuff. Now I don't know. Always something to learn about out there, eh...?!

As for a membrane, I'd only use it under the stone which I intend to cover the deck with, not on the rails and underside surfaces. So it really wouldn't come in to play looks-wise. It sure would be nice just to slap that stone down on the sealed decks though. That's my thinking anyway.

You're going to have to give me some time on those finished photos; it's a whole lot easier to draw stuff in chief than actually get it built, LOL!

[widco]

Hi everyone, new the the site and getting interested in CA.

What if you installed 3 strong steel posts that extended to the rail height- 2 near the building where the deck meets and 1 centered on the front edge of the deck and set in a footing that could be concealed the the topography. Now concealed steel cables from the tops of these posts could connect to the cantilevered corners like a suspension bridge. There would be 4 cables, 2 for each corner @ 90 degrees to each other and the whole system could be hidden in the railing cavity.

[Chris M]

In my town 80-90% of commercial and High desity residential are pre cast or tilt up.The cost savings are approx 15%,The time savings >25% than in situ. Connections need to be cast.New lightweight concrete
will see half the weight and I guess twice the thermal insulation properties.It will have a hugh impact on single residential. But i believe it reqires special moulds to cast (and its yet to be used commercially).
Hence repetition of components-> standardisation of designs -> lower costs etc..etc.
Heres an expample of what goes wrong when std precast fails.....Thats one lucky dude thats alive today.
http://www.news.com.au/perthnow/stor...32-948,00.html
FYIW.. I must say Im disappointed with the up grade
Goodluck

[tompapa]

Hi Widco, I think that was the general idea by suggested by one fellow who suggested a truss system concealed in the railings. I don't get how to hang the thing though. There are some loose ends out there at the southwest and southeast corners of the deck. I think I'm on to something with the post tensioned concrete though so I'll pursue that one till it bears fruit or dead ends, whichever of the two. Appreciate the input though!

Oh yeah, Bryce from above, apparently post tensioning really helps with the cracks. Makes sense...

[tompapa]

I don't get how you'd do a cantilever on three sides of a house with pre cast Chris. Unless it was one huge slab, which is impractical in this instance.

[tompapa]

That's funny, my concrete guy used to do on site precast tilt ups in Australia.

[Chris M]

Heres some some advice our engineering professor told me
when you graduate.If you are going to remember anything remember this if you are the deigner.
1.. Never wear a rolex or zegna suit on site.
2.. Always keep your composure..never laugh or smile
3.. And when they ask where you studied engineering .Dont say anything
Chances are a reporter will be lining you up for a front page spread...and in your case tom dont tell them you used CA-cheers

[Drizit]

You could alway pour a suspended slab supported on Post placed in the high spots so that they cant be seen,Build with 30mil re-bar and fiberglass embedded concert to get it thin....
Then there was a site that i found some info on concrete that can be heated just by adding electricity to it the have some type of metal embed in to so can drop the snow load variable off but it still keep the strength there just in case some screwed up in the heat system...

[widco]

tompapa, sorry about that, I looked at a couple of the renderings and then read all the posts, worked on some other thigns, registetered then posted not realizing that the deck cantilevers the other directions also. So yeah, similar to the truss idea I thought some steel cable would add strength & versatility, but so much for my theory. It will be a cool detail when you figure it out, I wonder if some huge layering system could be invented like a big sheet of plywood, there must be some way. Good luck with that.

[Joe Carrick]

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.