Replies

1. 
   ted | Feb 26, 2008 08:19pm | #1

   You don't say what the support conditions are. Is it supported around the perimeter? Are you attempting to pour over an existing subfloor?
   As an alternative if the subfloor is in place it might be easier to lay down an inch of rigid foam lay down radiant heat and pour 2" of gyp-crete on top of that.

2. 
   dovetail97128 | Feb 26, 2008 10:39pm | #2

   True suspended slabs should be engineered by knowledgeable design people. There is a lot of engineering for that .

   They can't get your Goat if you don't tell them where it is hidden.
3. 
   nuvue | Feb 27, 2008 12:08am | #3

   I would agree to get engineering. We pour lots of suspended conc. in the islands and all are perimeter supported with conc. beams, or on conc. walls. Typically we use #4 rebar on 8in centers (the upper steel could be 10 inch centers, we call this rebar "temperature steel")
   Also around the perimeter is top steel, #4 bars 12 in. oc. This steel should end up approx. 1 inch below the surface. If the span goes beyond 16 feet we use #5 steel for the support steel and go to 6 inch centers.

   Yes you can remove the forms after two weeks of curing.

4. 
   BillHartmann | Feb 27, 2008 03:37am | #4

   Some of the ICF systems have forms for suspended floors. And if you are withing the range of their products they have it all engineered for you.

   And with radiant heat you need the insulation.

   .
   .
   A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
1. 
   caseyr | Feb 27, 2008 04:44am | #5

   Yoro -Not exactly sure what you mean by "suspended". To me suspended means to hang, but I doubt that you are asking about floors tht are hung from above. I will assume that you are talking about a concrete floor that is supported from walls and spans a space below the floor. Two commercial systems for concrete floors that can span up to 30' or more are:
   LiteDeck - http://www.litedeck.com/
   InsulDeck - http://www.insul-deck.orgThese systems use polystyrene forms that stay in place as insulation once the concrete floor as cured. I had a floor designed to span 20' and I believe the total thickness of the polystyrene, the concrete floor, and the concrete support beams that were cast in the Litedeck forms were about 11". Shorter spans would require forms with less overall thickness.If you don't need or want the insulation of the above systems, there are precast hollow core and solid concrete panels of less thickness than the above systems that span various distances. I was thinking about using hollow precast beams for the floor of my garage, but probably will not go that route.

   Edited 2/26/2008 8:44 pm ET by CaseyR

1. 
   yoro | Mar 07, 2008 07:38pm | #6

   CaseyR thanks for the tip on the insul-deck web site. The pictures there made it come together in this old finns (of Finland) head. I appreciate all of the response that the members gave me; thank-you men...and women if anyone was in that catagory.yours yoro

   Edited 3/7/2008 11:39 am ET by yoro

2. 
   Hudson Valley Carpenter | Mar 07, 2008 08:03pm | #7

   If you don't need or want the insulation of the above systems, there are precast hollow core and solid concrete panels of less thickness than the above systems that span various distances. I was thinking about using hollow precast beams for the floor of my garage, but probably will not go that route.

   Will you please share any links you have for products of this kind. 

   I've just begun considering building an attached two car garage with a driveway which would connect from an elevated road to the third story of the home.  I'm wondering which method and products would be the most cost effective.

1. 
   dovetail97128 | Mar 07, 2008 09:15pm | #8

   happened to catch this awhile back, might be someone you could talk to in the list of suppliers. ""To handle the job, DiMarco selected three precast concrete manufacturers: Empire Precast of Rochester; Lakeland Concrete Products of Lima, N.Y.; and Jefferson Concrete Corp. of Watertown, N.Y. Jim Boyce, president of Empire, says his company was involved in phase one and was called upon by DiMarco to consult on the second half of the project."" http://www.precast.org/publications/solutions/2007_summer/collegiate.htm
   They can't get your Goat if you don't tell them where it is hidden.

1. 
   Hudson Valley Carpenter | Mar 07, 2008 09:51pm | #9

   Thanks DT, 

   Lots of possible methods, including pouring sections on top of another slab nearby, like a tilt slab operation, and then moving them into place. 

   I like that idea the best so far. I'm just not yet knowledgeable about the engineering requirements and weight for a twenty foot span. 

   Considering the cost of fill for such a project, I'm happy to consider any other options.

    

2. 
   dovetail97128 | Mar 07, 2008 10:16pm | #10

   I don't either. What little I know about them came from being a super on a 2 jobs that used pre-stressed planks. All engineering was done by the manufacturer. Ours were trucked in and craned into place. Also the floor load requirements were for a winery so the loads were high as opposed to a residence.
   They can't get your Goat if you don't tell them where it is hidden.

   
3. 
   Hudson Valley Carpenter | Mar 07, 2008 10:49pm | #11

   Interesting engineering, such large voids running through them. 

   I've never seen anything like that before.  Thanks for the photos.

5. 
   Henley | Mar 08, 2008 02:04am | #12

   I helped on a project once where we used something called-
   Q-decking

   You laid steel beams out across the span every five feet ( can't remember actual interval) and set these steel pan between them.
   Very fast and simple.

   Something to think about. beats the heck out of building
   and removing forms.
   Also no crane.

   
   

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   Edited 3/7/2008 6:05 pm ET by Henley