Quick Answer: A 3 panel bifold door suits openings under 9–10 feet and costs $2,000–$6,500 installed. A 4 panel bifold door handles 10–16-foot openings and runs $3,500–$10,000. Opening width is the deciding factor; everything else follows from that. So you’ve landed on bifold doors, good call. But now the internet is giving you a wall … Read more