Sunroom addition This is an idea that seems better and better with each passing summer, but never quite lives up to its potential. Remodeling puts together a bare-bones 200-square-foot sunroom with 14 windows, 10 vented skylights, a sliding door and wiring for ceiling fans and sconces and still manages to to spend more than $74,000. A homeowner will be lucky to get $34,000 of that back in the sale price; a sunroom's value tends to drop by 54% or more. That's assuming you've built a sunroom in a climate that actually, you know, gets sun every so often. If you've made this splurge in the Northeast, Great Lakes or the Pacific Northwest, expect buyers to put a bit less of a premium on your view of the clouds. Home office remodel Listen, we fully understand the home office. There's a lot more telecommuting these days, there's still a need for a professional working environment and this keeps everything nice and clean when the expense reports need to be mailed out and the taxes need to be filed. That's great, but Remodeling says it's perhaps the least valuable home improvement you can make. Converting an existing 12-by-12-foot room to a home office with custom cabinets, 20 feet of laminate desktop, new wiring for electronics, cable and telephone lines and drywall and carpeting to cover it all up costs around $28,000. That same office won't be worth $12,000 when you try to sell the place to someone who actually likes the doughnut shop on the way to work and listening to the radio on the ride home. That's a 57% that may be worth consulting the accountant about before the next W-2 arrives.