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Why is plastic not used in home construction?
Category: Chemistry
Published: February 26, 2014
By: Christopher S. Baird, author of The Top 50 Science Questions with Surprising Answers and physics professor at West Texas A&M University
Plastic materials are used in several ways in home construction. Plastic has useful properties such as water resistance, corrosion resistance, electrical insulation, and durability. Here we are using the common meaning of the word "plastic": a synthetic moldable solid. Among the uses of plastic in home construction are:
- Sewage pipes. These are increasingly being made out of plastic such as PVC instead of metal because PVC is cheap, corrosive resistant, light, and somewhat flexible.
- Water supply lines. These are increasingly being made out of plastic such as PEX because PEX is cheap, strong, and flexible. The relatively high flexibility of PEX leads to better water flow and quicker installation.
- Fuel supply lines.
- Electrical conduits. These are channels that carry various electrical wires.
- Insulating coating on electrical wires.
- Housewarp. This is the weather barrier that is placed just behind the exterior siding of a house and serves to keep rain from getting into the house while letting water vapor out.
- Thermal insulation.
- Roof underlayment.
- Electrical boxes and wall plates for light switches and electrical outlets.
- Exterior siding. Plastic siding such as vinyl is often shaped to look like wood clapboard or wood shingles.
- Kitchen and bathroom flooring. Plastic flooring such as vinyl or Formica can have the look of traditional plastic, or is increasingly being made to look like hardwood or ceramic tile flooring.
- Kitchen and bathroom countertops.
- Frames for doors and windows.
- As a main ingredient in many composite building materials such as Glass Fiber Reinforced Polymer (GFRP).
While plastic is used in various roles in home construction as listed above, it is true that pure plastic is not used for structural components. Pure plastic is not used as the beams, planks, and wall studs that hold up a house for several reasons. First of all, plastic is simply not as strong as wood, metal, or brick. Also, plastic permanently deforms under stress (creeps), and is harder to nail, drill, and screw than wood. Many of these structural limitations can be overcome by mixing plastic with other materials to form composite building materials. If the structural components of your house are made out of composite materials, there is a good chance that a lot of your house is made out of plastic.