What is a loft addition? In California many homes have been built with high ceilings. If your home is already two stories with high volume or vaulted ceilings it may qualify for a cost-effective addition known as a loft addition. A loft addition is a common term used when converting a high ceiling into a new room. However, a loft addition is not limited to just building an open loft. High ceiling room conversions can be converted into a new bedroom or bathroom. In fact, a high ceiling can be converted into just about any kind of room you need as long as it meets building code requirements.