Interior Design Singapore HDB professionals are a competent design professional who is qualified to design, prepare, and submit any type of nonstructural, non-seismic interior construction plans and specifications to local building departments. Interior designer can create a specific atmosphere just by putting together several pieces and unifying them in a single theme. There are interior designers who have a bias for certain motifs like eclectic, modern or even country style. Some go for simple designs without the clutter.