Cast-iron drainage piping
Cast -iron pipe was once the universal material for underfloor, or basement, soil piping, It was also common in vertical stacks in houses built prior to the early 1960s. The above-floor branch lines serving these stacks may have been made of galvanized iron or copper, but cast iron was the backbone of every DWV system.
Some codes today still require cast iron below the basement floor, but the trend is clearly toward plastic drain and vent piping, from street to roof. Still, cast iron is present in most homes built prior to the 1980s, and builders in some areas continue to install it. If you hope to make any charges or additions to cast-iron plumbing system, you'll need to know how to cut it. You'll also need to know how to fit it with either cast-iron or plastic fittings.
Cast-iron pipe comes in 3-,5-, and 10-foot lenghts, in no-hub, single-hub, or double-hub configurations. Two hubs make for less waste when you need custom-cut lengths, but you can't use them as they are because one of the hubs would always be backward. A double-hub pipe has to be cut in two.
Cast-iron pipes without hubs are available for use with no-hub fittings. Standard cast-iron pipe diameters for residential use are 2,3, and 4 inches. Most existing homes have 4-inch soil and sewer-service pipes. However, with today's EPA-mandated low-volume 1.6-gallon toilets, it is becoming less common to install 4-inch pipes in new construction because of the reduced volume.