It's universally understood that kitchens and bathrooms sell houses — renovated kitchens and bathrooms, that is. And homeowners are spending more on these remodeling projects than before, as shown by the fifth annual Houzz & Home survey.

Houzz questioned more than 120,000 U.S. respondents, and their answers prove that people shelled out 12 percent more money in 2015 to update these spaces. New homeowners are leading that charge. Over a quarter of all renovations are driven by recent home purchases, and more than 1 in 10 renovators purchased a home in 2015.

Perhaps it's that "starting fresh" feeling that spurs newly minted homeowners to spend. Renovators of a recently purchased home invest more in their projects than other homeowners: $66,600 versus $59,800. They also tackle larger projects and are nearly three times as likely to go whole hog and change up all of their interior spaces than the average renovator.

"Recent home buyers tend to do more, spend more, and are more likely to hire professionals to help with their renovation projects than other homeowners," says Houzz principal economist Nino Sitchinava in a release.

Kitchens remain the most popular interior remodeling project, with 31 percent of owners giving that top priority. Bathrooms and living/family rooms follow, but then the list expands to exterior features, such as windows and roofing. Something else that's climbing in popularity? Installing home automation systems.

If folks are looking to sell, projects to enhance curb appeal, such as upgrades to exterior paint, roofing, exterior doors, and decks, are big. But in general, Houzz found that homeowners are content to stay where they are and makeover their current home into a "perfect" one. Nearly half don't want to leave their current lot, and a third say they don't want to say goodbye to their neighborhood.

"2015 was another strong year for the home renovation market, with homeowners continuing to increase investment in their homes," says Sitchinava.

Respondents say they finally have the time and money to pull the reno trigger, though millennials are more likely to finance their projects with a credit card than baby boomers.

And budget: What budget? Nearly one-third of homeowners take on a remodeling project without setting a budget. Roughly one-third also admit to going over their projected amount. When they overspend, they overspend big, pouring an average of $83,400 into the reno, while those who stay on track tend to spend about $52,300.

But here's the real shocker: Not setting a budget might cause you to spend less overall. Those with no initial budget tend to spend only an average of $44,100.