What is Rough-In Plumbing in the Construction Process

Learn what rough-in plumbing means and how it fits into the construction process.

Building a house or doing a major “to the studs” remodel involves many steps, including framing, rough electrical, and rough-in plumbing. The process of rough-in plumbing consists of installing water lines, drains, vents, and piping connections. During construction, rough-in plumbing is done after the foundation and framing are finished. Some rough plumbing can happen before the slab is poured.

Once the basic infrastructure is in place, it’s time to do the rough-in plumbing. This is a crucial step in the building process and needs to be done correctly. When the Rough-in work is complete, the local building inspector will visit the site and check the work. Once approved, the drywall can be hung, the walls closed and taped, and the finish plumbing process can be started.

Learn the differences between rough-in and finish plumbing when building a house or home addition.

What Exactly is Rough-in Plumbing

Rough-in plumbing happens early in the construction process. Installing vents, sewage systems, connections, and water supply lines happens after the basic framing is complete, initial services like wiring or pipes have been installed, and end-points, like outlets and fixtures, have not yet been installed. Rough-in plumbing is completed before the walls are closed.

Rough-in plumbing is the first plumbing stage when building a new home or home addition. It includes excavation and running underground pipes from utility connections to the house. The pipes are then routed through the open walls, vent stacks are run to the roof, drains are connected to the city sewer or septic system, water lines are connected to the main water supply, and pipeline connections are made. Once the rough-in phase of construction is complete and signed off on by the local building inspector, the finish plumbing phase begins.

Rough-in Plumbing Vs Finish Plumbing

Rough-in plumbing is the initial stage of the construction process and is completed before the walls are closed. The next step is the finish plumbing stage. This is when the plumber begins installing faucets, water system valves, under-sink drain assemblies, and other fixtures.

Finish plumbing follows the rough-in plumbing stage. After the walls are closed and taped, caps are placed on the roughed-in drain, water supply lines are removed, and the fixtures are installed. Under-sink assemblies and water valves are installed, checked for leaks, and tested.

The Rough-In Plumbing Process Step-by-Step

When rough-in plumbing is installed, the contractor will take three considerations into account, they are:

• Gravity: Drain lines are positioned so they angle downward. Gravity is a key component of any drainage system.

• Horizontal Drains: Your plumber will design your plumbing plan to avoid long horizontal drain runs.

• Venting: Wastewater systems must be correctly vented to avoid plumbing infrastructure issues in the future.

Step-by-Step Installation

Step 1: Excavate and Lay the Main Lines

The first step in any project is to excavate and lay the main water and drain lines. The area needed to run the water and drain lines must be excavated from the utility main connections to the structure.

Step 2: Measure and Drill Tub and Toilet Drains

After the main lines, the focus shifts to the bathrooms. Set and level each tub, mark where the drain will go, and drill a hole for the drain. Measure and mark the location of the toilet.

Step 3: Drill Venting and Drainage Holes

Your plumber will use a hole saw to drill holes to route drain lines and vent stacks through the wall cavities. The next steps are factoring in gravity and avoiding long horizontal drain runs, gluing drain fittings, and ensuring the vent stacks are extended from the basement to the roof and connected to the appropriate vent. The vent lines are then terminated outside.

Step 4: Drill Holes and Run Water Lines

Once the drain and vent lines are in place, your plumbing contractor will install the water lines. ¾” pipes are placed close to where they are required for the bathroom, kitchen, or water-using appliances like the fridge, dishwasher, and washing machine. They will then install ½ lines for each fixture.

Step 5: Externally Vent Plumbing Equipment

Any additional needed vent holes are drilled for equipment, including sump pumps, water heaters, and boilers. Check the blueprints for equipment locations and drill the holes for external venting.

Step 6: Complete All Tie-Ins

The next step is to tie in all the water, drain, and vent lines. Your plumber will connect the hot and cold lines to the primary water lines, the vent lines to the central vent stack, and tie together the drain lines for any half baths.

Step 7: Connect and Test the Water Line

The final step is connecting the water lines to the incoming service and installing the main shut-off valve. Your plumber will cap or install isolation valves on any currently open water lines. They will then turn on the water main to test the plumbing system for leaks.

Rough-in plumbing is just the start of the plumbing installation process. It is essentially putting in the plumbing infrastructure for the home. It’s a complex process best handled by a qualified plumbing contractor. Typically, an experienced crew can complete the rough-in process within a few days to a few weeks, depending on the complexity and scope of work. Once the rough-in work is complete, a walk-through with your local building department will verify that your project meets the local building codes. When your rough-in plumbing passes inspection, it’s time to close the walls and begin the finish plumbing process.

Are you considering a new build or major renovation? We can help you design and install your plumbing infrastructure, fixtures, and features. Let us help you design the perfect space to meet your needs! If you live in the Greater Madison area, call the experts at Degnan Design-Build-Remodel at (608) 846-5963. We can take your home to the next level of comfort, design, and function! Are you ready to learn more? We are always available and happy to answer your questions.