How Much Does It Cost to Add a Bedroom?

Cheapest to most expensive

The cost depends on whether you convert or build:

• Convert a den or finish basement space: $10,000 to $25,000
• Finish an attic into a bedroom: $20,000 to $50,000
• Build a bedroom addition: $25,000 to $60,000+

What makes a bedroom legal

To count and appraise as a bedroom, a room generally needs a closet, a minimum size, and an egress window or door for emergency escape. Adding an egress window to a basement or interior room is a common extra cost.