No. 2: Sunroom addition
You know from the word "addition" that this project doesn't come cheap.
Anytime you have to add on to the foundation -- and the footprint of your home -- the price climbs, says Michael Hydeck, owner of Hydeck Design Build Inc. near Philadelphia and past president of the National Association of the Remodeling Industry.
With a 200-square-foot room with skylights, low-E windows, automatic shades and a tile floor, "it's a major project," says Alfano.
It can make a big difference in your enjoyment of the home and -- depending on how it's configured -- help heat adjacent rooms, he says. "You can do some pretty creative stuff with this."
Return varies by market
Resale value will vary by region, Phipps says. "You have to look at what your market is."
In Las Vegas, homeowners are more likely to add a roof or cover to the patio -- something with privacy curtains, but no walls, says David R. Tina, an owner/broker with Urban Nest Realty.
Whatever you build, if you want to get the biggest bump to your home value, opt for a licensed professional and permitted work, he advises.