Parts for any type of construction, composed of plastic covers and gratings assembled together using different connecting systems, such as nesting, mortise and tenon, guttering or other types of connections, the space occupied by the grating being filled with a binding and insulating material formed from a mixture consisting of the following products, in the following proportions: 2 kilograms of plaster, 400 grams of wood waste, and 1.5 liters of water.