rouging a new basement bathroom on dirt floor
hi all and HNY – I’m in NYS and in the plumbing Code 306 “Trenching, Excavation, and Backfill” i’m trying to figure what is required for the rough on our particular basement project https://codes.iccsafe.org/content/NYSPC2020P1/chapter-3-general-regulations
Currently, the dirt floor is 9 feet below the bottom of the joists (see photos), but it will become 8 feet when accounting for the floor assembly; 6″ of gravel, 2″ insulation, vapor barrier, and 4″ slab that is about to be poured.
We need to do the rough plumbing but apparently, I can’t lay the PVC pipe directly on the dirt – I need to lay it on sand or minimally clean fill before we bury it in more sand and then cover that with up to 6″ of gravel.
So my conundrum… given the way the code is written, do I have to dig a shallow trench that goes to 9′ 6″? or is there a method where I can lay sand or whatever onto the dirt as it is today and in this way comply with the Code without digging a new trench just for these PVC pipes.
Any view on this? thanks in advance!
Replies
I do not think that the code says you cannot lay piping on the dirt. (unless the soil is too soft to support the pipe, then you need to dig a hole and fill with compacted gravel or similar) You just need to make sure the pipe is continuously supported.
You can lay out the pipe on that dirt, but it needs to be in solid and continuous contact with the bottom of the pipe (and a bit deeper where joints or elbows need more space)
It would be easier to get that gravel and lay the pipe on it, digging a bit where required to achieve the proper slope and keep the top of the pipe below your insulation. (4 inch PVC is 4.5 inches OD and needs to slope an inch every 8 ft, so if your piping runs over 12 feet you need more than the 6 inches from top of the highest point to bottom of the lowest point.)
Stone with smaller sizes and somewhat rounded edges will be easier to work with.
thanks. really helpful to get your read in this!
@UncleMike42 and company.
A follow up question. If we lay the PVC right on the dirt, what methods do you suggest we use to keep it from moving around when the gravel is brought in?
thanks again.
stake it
I would look at it the other way, how will you keep the gravel under control when placing it?
For that matter, how do you plan to get the material into your existing basement? Do you have a source identified? Will they bring distribution equipment?
It is good you are thinking this out before hand.
https://www.youtube.com/watch?v=rPJZ6wgru9c
https://www.youtube.com/watch?v=R24yYNhEE84
You can use some steel rod or rebar to help keep the pipes in one place as you put them together. It will be easier to get the slopes right if you already have some of the gravel/stone on hand. (followed by more gravel to support the pipes)
Will you need a plumbing inspection before the drain lines are covered up?
great. thanks, and nice videos! Now im actually thinking we need 3 types of gravel. one to bed the plumbing that is small enough to be tightly compacted and without any edges sharp that could damage the pipe over time. another used around the drainage tile that will provide appropriate space for bulk water to
move through easily, and perhaps a third type for the basement overall that can be compacted but not as tightly as the plumbing bedding. maybe i’m overthinking it. also I’m going to sleeve the rebar stakes with short prices of PVC where they meet the pipe since we probably don’t want steel against the PVC over time.
the basement is only 700 sqft and we’ve been doing everything by hand - so the gravel will come in through a chute in the window and distributed by wheelbarrow.
yes to inspections. as I’ve said to our guys at the building department; if only the inspector was on the job at the Notre-Dame in Paris… that said, I always trying to make visits to our site the highlight of their day.
from what I gather the size and description of gravel isn’t consistent regionally - so my main challenge now becomes sourcing the right materials and knowing that i’m asking for the right types of gravel. for anyone listening that works in Westchester County or the tri-state region, what’s your take?
You could treat the rebar as a temporary tool. Remove once the gravel is in place.
My plumbers leave the rebar in place, but I live in the "shaky" state and I think my inspectors expect to see the rebar. My choice for covering everything prior to concrete would be course sand. It tamps well, won't harm pipe and it shovels easier to spread around.