How to Plumb a Basement Bathroom Part 2 How to Plumb a Basement Bathroom Part 2
Installing a basement bathroom can be a complex undertaking regardless of the type of setup you are doing. If you have broken your concrete and installed drainage lines on a plain to run into an existing drain line located in the basement floor, then you also will not need a vent. The only reason you should be concerned about a venting system is if you are installing all new drainage into solid below ground lines that have no air return, to prevent blockages, due to air and water pressure backups.
Step 1 - Locate Your Main Drain Line
The main drain line in your basement bathroom is going to be the one that all your other drains are going to be pouring or flowing into from their respective drains. This is going to be your main shoot and to prevent back flows of water, you need to remove the vacuum effects that can be caused when you flush the toilet or run the shower. This vacuum can prevent the water from flowing out, but instead cause it to flow up and into your bathroom sinks and even overflow onto the floors without proper ventilation.
Step 2 - Install T-Bends and Elbows into the Main Line
At the intersection of what will be your main drain line in the basement bathroom, you will want to install run in lines from the other drains in the new room. This would include the toilet, and sink, as well as the main line for the shower or tub drain as well. This will all work on a gravity feed system, and you will need to make sure that the angle in which they run into the main drain is at a lower degree than the unit you are draining. As an example, if your sink drain is located at 4 feet, you will want it to run into the main drain line anywhere between 1 to 3½ feet so gravity can pull the waste downward properly and out of your home to the sewer.
Step 3 - Making the Ventilation Stack
Where your main line comes together for the basement bathroom, you will want to build what is called a ventilation spout or facet. This needs to be above all drains no less than 4 feet, with its topmost end exiting your home and covered with a vent cap to prevent bugs and birds getting into it. Unless your basement floods or the drains get clogged, you should never see waste coming out this line from the side of your home. Simply attach an added length of pipe to your main drain line and brace it as it gets close to an area where you can t-bend it out the side of your home. Once finished, add your vent cap, and test the system for leaks after the piping has been allowed to dry.