PL1 is the file extension given by 3D Home Architect house design software. PL1 files are used to store the design of one-story buildings, most often the first floor. It includes a floor plan, equipment, location of light sources, etc.

Designs of subsequent floors are saved in PL2, PL3 files, etc. 3D Home Architect does not require great design knowledge and, apart from architects and builders, is also used by other users.