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How to Build a New Bathroom Using Your Existing Plumbing

Adding a new bathroom to your home is a great way to address bathroom time issues when you only have one or two bathrooms and need more. Maybe you would like a half bath downstairs so you don’t have to run upstairs every time you need to use the bathroom.

You might want a small bathroom added onto your outdoor kitchen and pool deck area. You can shower after swimming and have an easily accessible bathroom when entertaining guests at a BBQ cookout or pool party. Before you start tearing out drywall or building new walls, there are several design aspects to take into consideration when adding a new bathroom to your home.

Where are the existing plumbing lines and electrical wiring?

You will need to run bathroom plumbing, drainage system lines, and electrical wiring to the new bathroom. It is important to choose an area of the home that has easy access to each of these. You can also choose an area of the home where it will not be difficult to extend existing plumbing and electrical wiring to the new bathroom.

In this first example, you want to build a bathroom on the opposite side of the wall that is your laundry room. Extending plumbing and electricity from the laundry room would be fairly easy. On the other hand, you may really want a bathroom attached to your bedroom. However, the existing bathroom is on the other end of the floor, but your bedroom is over the kitchen. It would be more feasible to run plumbing from your kitchen to your bedroom so you can have the master bathroom you desire.

As you can see, the location of existing plumbing doesn’t always have to be right next to the area where you want to build the new bathroom. As long as the plumbing lines are within close proximity, it will help save on your construction costs. Even in cases where there is no plumbing nearby, you can still build your dream bathroom by having new plumbing and drainage system lines installed—although, this can add to your project costs.

Where will the new bathroom be located?

There are all sorts of places around your home where you could install a new bathroom, such as:

  • Closets: A decent-sized closet can be converted into a bathroom, for example, if you have a closet on the main floor of your home no one uses. Converting the closet would give you the bathroom you desire.
  • Hallways: Another area of the home you could use is your hallways if they have any unused space. For example, hallway dead-ends with no adjoining doors in a 5×8 foot area can be converted to an additional bathroom.
  • Existing Bathrooms: Sometimes you don’t like your current bathroom layout and features. Other times, you want to take a small bathroom and extend it into a closet to make it bigger. You could also take a larger bathroom and divide it to make two smaller bathrooms instead.
  • Bedrooms: Do you have extra space in your bedroom that goes to waste, like a corner or extra closets? These spaces could be used to build that master bathroom you have always wanted.

How will the new bathroom be ventilated?

You will need to run a vent pipe for the toilet and a bathroom fan. Make sure the room you choose has easy access to an exterior wall or roof. The vent pipe and bathroom fan exhaust can be installed through an exterior wall if roof access is difficult. Depending on where you are installing the new bathroom, you may also be able to tap into existing vent pipes and fan exhaust lines.

10 Steps to Build Your New Bathroom

Once you determine where you want to add the new bathroom, you will be that much closer to starting your renovation project. Prior to starting, you will want to create a bathroom design that details where the toilet, tub/shower, and sink will be installed. Your design will also help you determine what materials you are going to need so you can create a budget for your project.

Step 1: Schedule an in-home consultation with a bathroom plumbing professional.

You should consult with a bathroom plumbing professional to verify where your existing plumbing and drainage lines are located within your home. You need to make sure plumbing can be run to the location where you want to build your new bathroom. Your plumber is happy to provide advice, as well as a free quote for installing the new plumbing.

Step 2: Prep the room.

After you know how you are going to run plumbing to the new bathroom, you will be ready to start preparing the room. The amount of prep work required will depend on where you are constructing your new bathroom.

If you are converting a closet, you will want to essentially “gut” space. This requires removing existing shelving and flooring. You will want to also remove any drywall in the locations where the plumbing lines will need to be installed.

If you are building a new bathroom by enclosing an open space, like at the end of a hallway, you will still need to remove flooring, as well as the drywall where the plumbing will be installed. In addition, you will need to build the framing to enclose the space.

Step 3: Install vent and drainage system lines.

It is highly recommended to have your plumber install vent and drainage system lines. You want to make sure they are up to current building codes. Your homeowner’s insurance may even require a professional to do the work since it may need to be certified for coverage. Your drain line installation should also include any bathtub, sink, and shower plumbing.

Step 4: Install water supply lines.

After the vent and drain lines are installed, it is time to run the new water supply lines. You will need separate lines for hot and cold water. As an option, if you only want to run a single cold water line to the new bathroom, you could have a tankless water heater installed in the bathroom to provide hot water.

Step 5: Install electrical wires and outlet/switch boxes.

For this step, get an electrician to install these things if your plumber is not certified to do electrical work. You need to make sure the wiring and outlet/switch boxes are up to code. In addition, you may need to have a new breaker installed so you do not overload existing ones. This is also a good time to have any ceiling light fixtures as well as the vent fan installed.

Step 6: Hang drywall and paint the walls.

Now that all the vent, drain, and plumbing lines and electricity are run to your new bathroom, you can hang up drywall. Remember to cut out openings for water supply lines, electrical outlet/switch covers, and wiring for your wall-mounted light fixtures. Once all the drywall is up, you can seal and paint it.

Step 7: Install the bathtub or shower.

Have your plumber assist with the installation of your bathtub or shower since you will need to connect the tub and shower plumbing and drain lines, as well as the faucets and fixtures. If you are constructing a shower enclosure, this is when you would take care of this task too.

Step 8: Install the flooring.

Now is the time to install the flooring of your new bathroom. Make sure to leave an opening for where the toilet will be installed if it is a floor-mounted toilet.

Step 9: Install the toilet.

Toilet installation should be after you install the flooring. It does not matter whether your toilet plumbing is for a floor-mounted or wall-mounted toilet.

Step 10: Install the bathroom cabinets, countertop, sink, and mirrors.

As your new bathroom addition is nearing completion, this is the final step. You may want to have your plumber take care of installing the sinks and fixtures and connecting the water supply and drain lines. If you opted for a tankless water heater in the bathroom, this is when you would want your plumber to install it, especially if it is being installed under a cabinet.

Finishing Touches

Depending on the bathroom design you created, you may still have some finishing touches to complete, such as:

  • Hanging Up Towel Bars
  • Installing Wall-Mounted Light Fixtures
  • Hanging Up Pictures/Wall Decorations

Once everything is completed, give your new bathroom a detailed cleaning and enjoy it! Remember to take pictures at each stage, so you can share your new bathroom addition on your favorite social media site.

For assistance with installing new bathroom plumbing, drainage system lines, sink installation, and other plumbing needs, please feel free to contact MET Plumbing & Air Conditioning at 281-599-3336 today! We can even take care of running new air ducts for heating and cooling your new bathroom!

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