房

Upper-left 户 depicts a single-leaf door (half of 門). It is the indexing radical and supplies the meaning - a 房 is a room or building you enter through a door. Many household and dwelling chars share this radical: 扇 (door panel), 所 (place), 启 (open up).

Bottom-right 方 supplies the sound (fāng → fáng, tone shift only). 方 originally pictured a plough, later abstracted to 'square / direction'. The square shape harmonises faintly with the rectangular floor-plan of a room, but the active role here is phonetic. Same phonetic surfaces in 防, 访.