The first major phase in the construction of this year's Michael Holigan's Your New House Project House, is the plumbing rough-in.

It's called a "rough-in", but installing the backbone of a house's plumbing is actually a very precise bit of craftsmanship. The plumbers must calculate exactly what dimension of pipe or PVC is needed in every part of the house, then dig trenches and set that pipe so that it comes out exactly the place where the sinks, tubs, toilets and vent stacks will be. And don't forget the walls! In the Project House, many of the pipes will eventually extend up into the second floor, so they must be perfectly placed so as to fall inside a wall.

The basic concept of residential plumbing is very simple - fresh water, under pressure, comes into the house from the city's fresh water line and is distributed around the house by a system of water pipes. Sewage and wastewater, flowing downhill, are collected by a separate set of sanitary drainage pipes that connect to the city's sewage line, which is always several feet below ground level, to ensure the proper fall.

However, making that "simple" process happen smoothly, efficiently and safely takes a considerable amount of planning and craftsmanship.

Measuring, Marking and Trenching
At this point, in the construction, the foundation crew has set the wood form boards that mark where the outside walls of the house will go. Working with a set of plans, the plumbers determine where they have to dig the trenches that will hold the sanitary drainage and fresh water lines, and mark these measurements on the form boards. Then they dig trenches for the main lines.

One very important consideration for the plumbers at this stage is to make sure that there is a constant downhill slope from the farthest sanitary drainage point to where the house's sanitary drainage connects to the city's sewage line. In our Project House, we're using 3" PVC pipe for the drainage, which calls for the plumbers to maintain a quarter-inch fall per foot of flow. Because of the size of this house, that's going to mean a total drop of at least 40" from the farthest point in the house's plumbing to the outflow point.

Water Lines
The plumbers use coiled copper for the water lines that will run beneath and throughout the foundation. Because the coiled copper is a continuous tube, there will be no joints within the concrete or below the slab. Wherever the copper passes through the concrete, the plumbers will place a sleeve over the pipe (red for hot water line, blue for cold). This sleeve acts as a cushion against the pressure that comes from thermal expansion and contraction. By sleeving the copper and not holding it rigid in the concrete, there's room for flexibility.

In the 1800's plumbers used iron to plumb houses. Later, in the early 1900's, steel was used. For the last 50-75 years, however, copper has been the metal of choice because of its flexibility, longevity and resistance to temperature extremes. Copper is also "biostatic", meaning it inhibits the growth of harmful bacteria.

Tips for Consumers about "Sweating" Copper Pipe
Be sure to ask your plumbers if they "ream" inside of the copper tubing before soldering, or "sweating" joints. This procedure is actually required by the American Standards Testing and Materials (ASTM) 828 protocol, which has been adopted as code by most municipalities. If the plumber doesn't ream the inside lip of the tube after cutting it, a spur can develop. This spur can disrupt the even flow of water inside the pipe and, over time, cause corrosion and pitting to occur, which can lead to leaks. (For more on this, see our video).

Another thing to ask your plumbers is whether or not they are using water-based fluxes, as opposed to the traditional petroleum-based fluxes. Petroleum-based fluxes can lead to copper pipe failure. According to the Copper Development Association, current code requires the use of ASTM B-813 standard water-based fluxes for use in residential drinking water systems.

Testing and Inspection
Once the "rough" plumbing is installed, the plumbers will "stub out" the pipes so that they rise to a level at least four feet above the eventual level of the foundation concrete. The plumbers then tap into the city water line and sewer lines.

Now it's time to prepare for the plumbing inspection. The pipes are filled with water, and the four feet of vertical water in the pipes creates a gravitational pressure in the system of still-exposed pipes. If there are any leaks in the system, the level of the water will fall by a noticeable amount over the next 24 hours. If there are no leaks, the city's plumbing inspector is called.

Our Project House passed the plumbing inspection on Friday, June 1, 2001.

To see the full story, on television, watch for the "Plumbing Rough-in" segment on Michael Holigan's Your New House in September.

Contact Information:
Copper Development Association
1-800-CDA-DATA (232-3282)