Structural Slab on Piles - Piping
Structural Slab on Piles - Piping
(OP)
I am working on a project that has a first floor slab supported on concrete piles. The soil is all muck underneath. How are conduits and piping typically supported in this case. I was thinking of hanging a duct bank under the slab, but I am not sure. Also, what is the method of construction for these slabs? Do they use stay-in-place forms for the slab soffit or something else.
Lastly, for vapor protection do you cover the soil with visqueen or do something else.
Lastly, for vapor protection do you cover the soil with visqueen or do something else.






RE: Structural Slab on Piles - Piping
I usually hang the piping that is placed under the structural slab on grade by hanging them from the structural slab on grade. They system should be designed so that the "muck" under the slab can sink w/o adverse problems to the building. If the piping is resting on the "muck" it will sink when the "muck" sinks and you will have a problem. I usually leave the spacing and type of hangers up to the piping contractors but make sure something is shown on the drawings and the GC knows of the reason why they should be there.
Most of the structural slabs I have constructed have used grade as the form for the underside. It is usually leveled off then reinforcing is placed and concrete poured. Depending on your soil conditions results may vary.
I don't know what visqueen is, but I assume it is some sort of plastic sheathing. I usually show a vapor barrier placed under the soil that is used to for the structural SOG but don't get to worked up if they place the sheathing directly under the slab. If you have grade beams or footings you will need to figure out how to block the vapor from coming up through the beams and footings (not that hard to do).
RE: Structural Slab on Piles - Piping
RE: Structural Slab on Piles - Piping
The piping is placed before construction begins on the slab. One thing to keep in mind is what cover you need to use for your bottom bars. If the slab is cast against soil you need to use a cover of 3". If you use some sort of form (like a void form) you can use a smaller cover.
RE: Structural Slab on Piles - Piping
I assume that you will be placing the slab on the soil right? If not then the question can get more complicated but you would have to remove the forms.
RE: Structural Slab on Piles - Piping
As far as Visqueen, make sure it's heavy enough to not get damaged during construction, at least 10 mils. Even though I don't think much of vapor barriers, I think even less of them when they're poked full of holes.
RE: Structural Slab on Piles - Piping
RE: Structural Slab on Piles - Piping
How would I do this for the sewer lines? They will be gravity fed.
RE: Structural Slab on Piles - Piping
RE: Structural Slab on Piles - Piping
RE: Structural Slab on Piles - Piping
I worked on a project about 2 years ago where the top soils could support construction equipment but once you broke through the top layer you were in trouble. I remember the GC trying to place a catch basin and having it sink out of sight under its own weight. It was actually kind of funny because we had extensive discussions about placing the utilities on piles which the contractor said wasn't necessary. I guess they were wrong.
RE: Structural Slab on Piles - Piping
"How would I do this for the sewer lines? They will be gravity fed. "
For story below pipes, sump pit with pump can be used.
RE: Structural Slab on Piles - Piping
RE: Structural Slab on Piles - Piping
RE: Structural Slab on Piles - Piping