If you want to install a bathroom in your basement, then you will need to add a drain vent to the system. This will ensure that noxious gasses don't build up inside the pipes, as this can lead to explosions, pipe damage and further trouble for your system. You could ask a plumber to install this vent, but this could be expensive, and it is something that you could do yourself with the right equipment. Adding a bathroom drain vent is not too complicated, although you will have to ensure that the vent goes all the way to the roof.
Check Building Codes
Before you can install the pipe, it is important to check that you can comply with local building and plumbing regulations. In some areas, certain types of venting is not allowed (for example, wet venting). You should already have secured permission to install the bathroom in your basement, so adding the drain vent should have been discussed. If it has not been, then you should read the regulations for venting, and also call the building's inspector and ask them about the specific venting conditions.
Use PVC Pipe
PVC piping is the best way to ensure that your pipe will stand the test of time. Even though you will just be venting air, you might still get moisture in that mix which could cause rust. Avoid having to replace the drain vent pipes by using plastic right from the start. Plastic pipe is also more economical to use than metal pipe work, and this can be an important consideration when you are doing a major conversion like installing a bathroom in the basement.
Ensure Pipes Are Large Enough
Make sure that the pipes you will be using are large enough to vent the drain. Pipes which are too small will not vent properly, and you will reduce the entire reason for adding them in the first place, which is the elimination of gasses from your drain. You will also need to have short pieces of pipe, so you can add plastic connections, including clean-out points which will help ensure that the pipes remain clean.
Fit Pipes and Drain Traps
You need to position your drain vent pipes close to the drain trap. This will ensure that the gasses don't build up before they reach the vent, as this could damage the pipe despite your best efforts. You will also need to align the waste trap so that the fittings match closely, otherwise you will be putting too large a stress upon the trap.
Use Proper Fittings
You should also use proper fittings, and ensure that they are correctly aligned with the pipes. Stop valves in particular should not be forced onto the end of the pipe, as this can push the compression ring out of alignment, meaning that the vent will leak. Instead, use a plumbing manual to guide you about the correct position of each fitting.