Underground Plumbing
Tuesday, November 24th, 2009
Once the digging is done, a lot of planning takes place. First, you have to mark exactly where you want the house with accurate corner pins and string lines. Then, you have to consult your drawings and mark where your plumbing pipes are going to come up under your house.
The kitchen sink pipe (2″) has to come up either in the wall behind the sink, or inside the kitchen cabinet, preferably in a corner.
The washer drain (2″ or 3″ depending on local code), must come up in the wall next to, or behind the washer. If you are even an inch off, the whole wall has to move, so measure ACCURATELY!
The toilet drain (3″) has to come up 12″ inn from the finished wall behind the toilet. Vanity (2″) must be inside the wall behind the vanity, and the bathtub pipe depends on what is happening. If you don’t have a crawlspace, it is common to put the pipe into a small sandbox under the tub. After the concrete is poured, the sand in the box can be dug out, and the pipes connected. If you do have a crawlspace, the bathtub pipe can come up right under the wall, just like the vanity pipe does.
In our case, we ran the main drain pipe in a 45 degree angle through the house, so all the branches connect with 45 degree long sweep elbows. Make sure the pipes have the right fall, to. It is supposed to fall 1/4″ per foot, or 2 1/2″ per 10 foot. All the branches has to hit the main drain at the right level (which is sure to give you brain burn before the day is over). Don’t forget to put a cleanout outside the house (we put one outside each bathroom as well).
This part is never fun, but once it is done, that’s that, so hang in there, and good luck with the plumbing inspection.
Tags: underground plumbing



