Average cost for adding 15x15 room to a house?

The average cost to add a 15x15 room to a house typically ranges from $15,000 to $40,000, depending on factors such as location, materials, and complexity of the project. Basic construction may be on the lower end, while high-end finishes, permits, and utility connections can drive costs higher. It's essential to obtain detailed quotes from contractors for a more accurate estimate tailored to your specific needs.