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- over 420,000 Posts - PlumbingForum.com -
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Author:
sum (FL)
If you have a buried pipe (3" CI) under the slab, and you cut open the slab and replaced/repair a section of it, now the soil has been disturbed.
The new section is about 5' long in PVC, it is supported on both sides. Now I am ready to backfill with soil which is mostly sand.
Do you typically wedge in a couple of rocks or concrete under the pipe fittings before you push the soil back in? Or is it better to just backfill with uniform soil and really pack down the soil?
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Author:
waukeshaplumbing (WI)
i like to use gravel, but sand is legal..atleast here in WI
take your shovel and jam it around the pipe to compress the gravel
when you step on the pipe it should not move
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Author:
royboy
For the minmal cost, I too like gravel. Sand will still settle unless it is well compacted.
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Author:
sum (FL)
I will be wetting the sand down too.
But do you support the pipe in a few spots with some big rocks?
For example, if you have a pipe at 1/4" per foot and then with a 3"x4" elbow to go up for a toilet, do you support the bottom of that elbow with a piece of solid concrete or rock? because if it slips down a little it could suddenly be slowing UP 1/4" per foot and that's bad.
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Author:
dlh (TX)
no! you should not need to support the pipe as it should be in a graded ditch. pour some sand around the pipe and then walk it down on both sides of the pipe covering about 1/2-1/3 of the pipe then walk on the pipe and look for the pipe to bounce. where it bounces you take something (like the other end of a shovel) and jam the sand under the pipe until there is no more bounce. then repeat for the length of the piping
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PLUMBERS "Protecting The Health Of The Nation"
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Author:
packy
fine sand 6" in all directions of the buried PVC pipe. (mass code) no rocks...
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Author:
Shoemaker2 (MA)
If you wanted a little over-kill you could use 1A Bands and bent rod and hang it from the concrete like they make us with no-hub underground.
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Author:
hj
Youuse your shovel to jam the dirt UNDER the pipe so it CANNOT move downward.
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Author:
A1APLBG (GA)
Sum I hope you are having all those holes you cut into the floor of your house where you distrubed the dirt re-treated for termites.
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Author:
nhmaster3015 (NH)
Compact the sand first under and beside the pipe. then take two pieces of 1/2" re-bar and insert them beside and under the pipe at a 45 degree angle forming an x into which the pipe lays. Wire the two tops of the re-bar above the pipe. this should be done at every fitting location and every 48"
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Author:
dlh (TX)
a little on the side of over kill wouldnt you say?
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PLUMBERS "Protecting The Health Of The Nation"
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Author:
nhmaster3015 (NH)
Round here it be code.
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Author:
sum (FL)
yes i do plan to retreat for termite and a new vapor barrier.
Oh one more thing...where the pipe exits the house, the concrete block wall goes deep to the foundation, so the pipe exits below the slab, but above the foundation. There is a irregular hole cut through the block wall for the pipe to go through. The hole was not patched with concrete...as you can see in this picture which was taken from the outside of the house, there was this big tree root that came from a tree 28 feet away in the swale area that ran up alongside this CI pipe, I cut it off. What I did not know at the time was how far into the house this root got. Recently I replaced all these fittings and also inside this wall, and this root went inside for about 5 feet before it stopped!!! It never found a way to get into the pipe, but it went through the wall through this irregular shaped hole, which I enlarged a little further because I have a PVC fitting with a hub that needs to be on the inside of that wall.
Do I patch this hole up with concrete to seal off water and further root intrusion? or do I use those expansive foam spray that claims to "harden" as solid as rock?
Edited 3 times.
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Author:
dlh (TX)
the best way to have done it is to have installed a sleeve then use a "link" seal. it is not recommended to seal the pipe itself with something that does not allow for movement as a subtle shift in the ground could easily snap the pipe since it will move in the dirt but not the foundation (hopefully).
but to keep the roots from getting under the house anything short of solid will not work
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PLUMBERS "Protecting The Health Of The Nation"
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