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Adding a Basement Bathroom & What You Need To Know

By Mike Holmes

Mike’s Advice / Bathroom Renovation

Thursday, April 23rd, 2020 @ 2:49pm

If you have chosen to add a basement bathroom, that’s great. A bathroom in your basement is useful if you have guests over a lot or if you have a rental unit. Also great if your family spends a lot of time in the basement. A bathroom remodel is also a smart investment to increase the value of your home.

Are you adding a basement bathroom to a new house or an old house? Usually, older homes won’t come with a rough in. If your basement isn’t set up to include the necessary systems like drains and plumbing vents, you will need to have them added. In the case of a drain, it means routing piping below your floor, which in most cases means breaking up a portion of your concrete to add a drain, not to mention regarding the slope so that the water actually flows INTO the drain. You may even need to install a special upflush toilet depending on where your main drain line is found in the home.


Common mistakes I see in basement renovations.

Hire a Professional

Basement bathrooms present unique challenges. The convenience of an extra bathroom comes with a lot of appeal for homeowners. But do it right, with proper planning and permits, so I don’t need to come in and fix it. Installing a basement bathroom is not a simple DIY job—that’s why there are professionals with experience and training to do it for you.

I’m not sure why, but basement bathroom installations seem to attract contractors who love to work without permits. I commonly get emails from fans that say something like this, “I want to install a bathroom in my basement. My contractor says I don’t need a permit but I thought I did. Do I need one or not?” Yes. You will need permits, and I would walk away from a contractor who tells you otherwise


What you need to know about permits.

Ventilation in your Basement Bathroom

An exhaust or ventilation fan is a necessary addition for basement bathrooms so that moisture can be removed.

Photo of Holmes Approved Homes builder Charette Custom Homes

Again, if your home isn’t roughed in for a basement bathroom, you’ll need to add the proper vents. This is going to mean cutting into concrete, drywall, and other building materials to direct that exhaust safely out of your home.

Flooring for your bathroom

Typically, you’ll see the tile in a bathroom- and that’s a good choice for your basement bathroom too. But what goes under your tiles?

Installing an uncoupling membrane between your concrete and your tile is important to prevent cracking. Because of temperature fluctuations, the concrete substrate expands and contracts naturally. Installing an uncoupling membrane between your concrete and your tile keeps the two materials independent of each other. So that when one moves, the other doesn’t move with it, which stops the major cause of cracks.

The uncoupling membrane (Ditra) we use, even allows for the installation of heated flooring.

Mike Holmes DIrta Heat

The uncoupling membrane (Ditra) we use, even allows for the installation of heated flooring.


Looking for inspiration? Here are some bathroom ideas you will love.

Lighting Choices

Space in your basement bathroom may be at a premium – so don’t waste it. Your basement ceiling may already be fairly low, so be careful when picking out your lighting fixture.

I recommend installing recessed or pot lighting in a basement bathroom like in this home from Precision Custom Homes.

They will provide enough light, without taking away valuable headroom. To add enough lighting, you can even have them installed inside the shower. But these lights have to be rated for use in a wet zone. When they’re installed properly, with a good quality trim that resists water and vapour, it’s completely safe.

Don’t forget about bathroom sinks that can bring a lot of style to your bathroom like this his and her sink from Kraus

Your Basement Toilet

If there is no drain for your sewage currently, one will have to be created in your basement floor that ties into the main waste pipe. 

It’s important that it be sloped properly, because..well because you know exactly what will happen.

Your contractor will have to tie into an existing vent on an upper level, or put in a new one that vents out of the roof of your house. That’s also messy—drywall, roofing repair, painting—and a lot of work.

If you have an old house, your main sewer drain may be higher than the level of your basement. What you’ll need to install is an upflush toilet—or a sewage ejection system. Basically, there’s a special lined sump hole cut into your basement floor slab, and the macerating system for the sewage ejector sits in that. It grinds and shreds waste and paper in a few seconds, then mixes it with the water from the toilet reservoir upon flushing. Then this material is pumped up through a pipe that ties into the main waste drain. 

Ready to renovate? Start with the home renovation jobs that will help you recover your investment. Read my article on 8 home renovations that will add the most value to your home.


 13 Bathroom Ideas You Will Love 

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