Adding a Basement Bathroom? Here’s Some Things You Should Consider

Basement Bathroom

Are you thinking about adding a bathroom to your basement? If you have a guest bedroom,  gym, entertainment room, or an office in your basement, adding a bathroom will keep you from climbing up and down the stairs every time nature calls.

However, this is not a simple project and there are some things you should investigate before taking on a renovation of this size. ​Even if you have previous experience with adding bathrooms, underground plumbing can be tricky and complex, and it should be left to the professionals. ​

However, if you insist on undertaking the project, we highly recommend hiring a plumber for a consultation at bare minimum. He can assess your individual situation and give you advise. You'll have a good idea of what the job will entail, and if you choose to tackle it yourself, you'll be prepared for some of the challenges.

Adding a bathroom in your basement will undoubtedly increase your home's property value, not to mention making your life easier. But there are a few things you should take into consideration before undertaking such a major project. 

Planning Considerations

  • Contact your local building authority - Projects of this nature often require permitting. There may also be deed restrictions and zoning ordinances involved. 
  • Location - Where you want to build your bathroom may not be the best location. It should, if at all possible, be put as close to existing plumbing and electrical wiring as possible. The most cost effective location is to build it directly beneath an upstairs bathroom.
  • Scope of the Project - How big do you want your basement bathroom to be? Should it be a full bathroom with a shower and bath? or will a toilet and a sink be sufficient?

Plumbing and Building Concerns

The most critical concern with basement bathrooms is drainage. Aboveground bathroom plumbing utilizes gravity. Wastewater and sewage is moved down pipes with a little help from gravity. In the plumbing world this is known as "slope" or "fall."

However, with a basement bathroom there often isn't enough of a fall to move the waste water from a sink or shower. Toilets also rely on gravity  to drain away sewage. 

A contractor will review the depth and size of your plumbing to determine if it is capable of handling a basement bathroom. Here are a few of the things you should he consider:

  • Plumbing Size

If your current drainage pipes are undersized, it'll be necessary to install larger ones.

  • Plumbing Depth

The sewer line may be at a depth that will allow your basement bathroom to work on gravity in the same way your plumbing does upstairs. Contact your local public works department. They can provide you with details of the depth of the sewer lines.

If you are not on sewer and use a septic tank instead, you'll need to find the depth of your home's septic lines. Frequently, builders leave this information on the building plans or other documentation turned over to the homeowner at the time of purchase. 

Many basements were built with the option of adding a bathroom in the future. If this was the case, the job ahead will be considerably easier. Frequently there are plumbing stubs already in place. 

It may be necessary to excavate the ground below the basement floor to create enough fall for your drainage lines. Although, unfortunately, there are some homes that even this won't be enough. If your home falls into this category, there are specially designed toilets for these situations. 

  • Flow Rate

Assuming that your plumbing is deep enough and of adequate size, the next concern is flow rate. If the flow rate is too low there won't be enough water flow to remove the waste.

  • Back Flow Valve

A back flow valve prevents sewage from backing up in the toilet. These are required for homes that are on city sewer lines and they usually require a permit to install. 

  • Toilet Options

There are many different options available for toilets in a basement bathroom. Plumbing is always a major concern when it comes to basement bathrooms, fortunately there are toilet options available for nearly every shortcoming.

Here are a few examples: Up-flushing Toilet; Pressure-Assisted Toilet; Composting Toilet; and Sewer Ejector Systems. Whatever your challenge, there is likely a toilet available to work in your situation.

  • Lighting Options

A well lit room is important in any part of your home, but especially in bathrooms. Take advantage of natural lighting and use glass-block windows if possible, they provide privacy as well as light. Combine ceiling lights and vanity lights to really get your bathroom bright!