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How to make plumbing for a bathroom add-on

The addition of new plumbing to an existing house can be complicated and expensive. After determining that the new bathroom can be located in the home, it is important to determine if your existing pipes are of a sufficient size to allow you to add in additional accessories. Generally, you can determine this by discussing your home and showing the provisional building plan of your local planning department. They will be able to help you understand the size of your existing pipe system and what permissions and issues you are likely to face with your addition.


  1. Measure the room or area you want to convert into a new bathroom. Sometimes, the room can be purchased from closets, bedrooms, terraces, laundry rooms or other rooms. Sometimes the construction of a new addition is necessary. Transfer your measurements to your graph paper.
  2. Draw the existing house (in the area where the new bathroom will be installed) and show the doors, windows, walls, doors, lamp changes, light sockets, existing plumbing fixtures and any other features of the room or rooms. It is important to show adjacent rooms to understand how the new bathroom will fit in or work with those areas. Be sure to add measurements.
  3. Place the tracing paper on the plan of the existing house. Draw in the shape of your new bathroom addition. Detail in which you want to install the elements and accessories (such as bathtubs, showers, sinks and toilets). If there are pipes near the location of the new existing bath then indicate the location of the pipe. For example, you may have a bathroom on the floor under your new bathroom location.
  4. Calculate a budget for your bathroom project that includes a written estimate from a plumber, electrician, carpenter, drywall and shingles, as well as the cost of all accessories, furniture and finishes. Add 10 percent for unexpected excess.
  5. Take your bathroom plan from your local construction department and discuss with your experts in the scope of your project. In general, the local building department can determine if the age and location of your home usually include plumbing that could handle the additional burden of a new bathroom. You will also be informed of the costs of permits and other construction issues related to your addition.
  6. Purchase permits and select a plumber with a good reputation. You can opt for a demonstration of the new bathroom area yourself to save on costs. Normally, this can be done with levers, hammers, drywall saws and a Sewall. Connecting an area of ​​the house where no plumbing currently exists typically requires the opening of the floor and the roof portions, where it is necessary to connect with existing plumbing.
  7. Open walls where new plumbing and electricity will be installed. Many of the new bathroom additions are demolished to the posts so that good access is provided to the wall cavities of the carpenters, plumbers and electricians. It is also necessary to provide an HVAC duct in most bathrooms that may require an additional subcontractor.
  8. Rough in the pipe once demonstration is completed. Rough-in includes all the water and drainage pipes / debris and a complete test of these systems to ensure that the new pipes are working properly. Often shower pans, bathtubs and toilets are installed during rough periods of entry. (Inspection requirements in your area may vary.) Plumbing inspections usually happen once the system is tested.
  9. Finishing the plumbing is when the plumber comes back after installing the cabinets, walls, ceilings and floors. The plumber will finish with installations and accessories so that everything is airtight, sealed and works properly. A final inspection is often required before the project is released.

Tips and warnings

  • Hire a certified and licensed plumber that is recommended by your Better Business Bureau. Check your pipes and electrical inspections. They must be signed on the back of the official permit. Take permission questions directly from your construction department for clarification. The amount and type of pipes you will need to add will depend on the size and complexity of your new bathroom and the age, size and accessibility of existing pipe systems.
  • Always look and read your permits and inspection reports yourself.

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