Adding a sunroom to your investment property may be a bad idea—especially if you’re looking for a quick turnaround with a hefty profit. Should You Add a Sunroom to Your Investment Property? The numbers don’t lie: Adding a sunroom to your investment property will get you, on average, about 50 percent of the project’s cost back when you sell. The average cost of building a sunroom is about $73,000, which could be better-spent elsewhere. Naturally, every house—and every buyer—is different; it could pay off differently for you. But like home offices, a sunroom looks like an inefficient use of interior