Adding a sunroom Projected return on investment: 46.5% This is another project Remodeling believes you'll recover less than half the price of at sale time. The magazine calculates you'll pay $72,200 to add a 200-square-foot sunroom with 10 skylights -- but raise your home's value by only $33,500. "A sunroom is a nice thing to have, but it's not something that's crucial to most buyers," Moore says. Building an upscale master-bedroom suite Projected return on investment: 52.1% Expect to recoup just over half of the $220,100 it'll cost to add a 32-foot-by-20-foot master-bedroom suite with a gas fireplace, custom bookcases, a spa-style bathroom, a walk-in closet and a bar/refrigerator. Moore says few house-hunters want master bedrooms that fancy. "I've sold $2 million homes that don't have a bar in the bedroom," she says. "Most buyers are too frugal for that." Installing a backup power generator Projected return on investment: 52.7% Moore says built-in generators have impressed Boston-area buyers ever since severe storms hit in 2011 -- but won't boost property values enough to justify the $11,400 that Remodeling estimates a whole-house system costs. The reason: Home-improvement stores sell small portable generators for $150 or less. "A lot of people figure they'd rather go the 'Home Depot' ( HD) route and have something that functions but isn't so expensive," Moore says. Adding an upscale garage Projected return on investment: This $80,500 renovation involves updating an existing two-car garage with fresh paint and drywall, molding, a modular storage system and an epoxy-sealed cement floor. Moore says the project only makes sense if you want a fancy garage for personal reasons and add it four or five years before putting your home on the market. "It's a good investment if you can use the garage yourself for a while -- but not if you're just putting it in to sell your property," she says. "You'll never make your money back." The Remodeling 2012-13 Cost vs. Value Report is copyrighted by magazine publisher Hanley Wood, but data from the study can be downloaded for free at costvsvalue.com.