Planning and installing plumbing rough in

When installing plumbing rough in don't be concerned with how rough it looks. It only needs to function properly and hold the required pressures, it doesn't need to look pretty. That's what finish work is for.



Plumbing may seem confusing, but it is really simple. Some of the plumbing codes might appear to be confusing at first, but even the codes are fairly easy to figure out.

I will talk about plastic pipes and metal pipes. Plastic is so much easier to work with though.

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Plumbing components consist basically of three things: 1. fresh water system, 2. the fixtures and the appliances, 3. a drain system.

Fresh water systems- These are the any pipes that come from either private wells or a city water supply. Fresh water lines enter the home through a mainline and usually make a branch at the water heater.

These lines are always pressurized and connect directly to the inlets on all plumbing appliances and fixtures (sink faucets, toilets, baths, outside spigots, washers, etc.). They can be galvined iron, plastic, or copper. They are usually small in diameter, usually ½ inch to 1 inch in residential applications. Water lines are connected with watertight fittings.

Fixtures and appliances- These are self-explanatory and obvious, but they each have special regulations and codes that will need to be observed before they are installed. Waterlines that connect to each fixture or appliance will need to be a minimum diameter, and the waste lines from each( toilets, sinks, showers, etc) will need to be a certain size as well. The pipe sizes need to be planned out well before the fixtures and appliances are ready to be installed.

A drain system- This is all the pipes that go from the appliances or fixtures to the city sewer system or the residential sewer system. The acronym for this waste system is the DWV (Drain-Waste-Vent). The drains will carry away all wastewater, but the bigger pipes that are part of the waste system carry away solids called soil pipes.

Also, part of drain waste lines are P-traps. P-traps create a water barrier in the pipe so that sewer gases won't get into the home. All appliances and fixtures will need to have P-traps in the waste pipe lines with the only exception of toilets. Toilets, by design, have the U-shape water retaining barrier that is basically a P-trap. Vent pipes that connect to waste lines allow sewer gases to escape through the roof.

Sewer gases can build up and break through the P-traps if the venting is done wrong. Venting also helps regulate atmospheric pressure, without constant and even atmospheric pressure, waste water can be sucked out of P-traps and the water seal is lost.


Each aspect of installing-plumbing-rough-in has certain regulations that will have to be approved by a plumbing inspector before the sheetrock is put on the walls.

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