Building material manufacturing apparatus and building material manufacturing method

A building material manufacturing method, implemented by using:

• a sieve portion including a series of sheets that have an inclination and that are arranged in a direction of the inclination, the series of sheets including a first sieve sheet and a second sieve sheet that is positioned below the first sieve sheet, the first sieve sheet being a sheet in which a plurality of meshes having an identical size are arranged at a regular pitch in a sheet width direction of the series of sheets, the second sieve sheet being a sheet in which a plurality of meshes having two or more different sizes are arranged in the sheet width direction or being a sheet that has a mesh region and a non-mesh region that are arranged in the sheet width direction;
• and
• a receiver for receiving a building raw material that has passed through the meshes of the sieve portion, the receiver being movable under the series of sheets,
• the method comprising:
• in a state in which each of the series of sieve sheets is performing a wave motion,
• screening a building raw material by using the series of sieve sheets;
• and
• forming, on the receiver, a mat including a first layer formed from a building raw material that has passed through the meshes of the first sieve sheet and a second layer formed above the first layer from a building raw material that has passed through the meshes of the second sieve sheet.