Homeowners used to count on stable housing costs. No more.

Americans have long prized homeownership for its financial benefits. It offers perhaps the most surefire way for many people to build wealth. And as long as buyers locked in a fixed-rate mortgage, the thinking has been, monthly housing costs were mostly set.

But that belief is increasingly being questioned as the overall costs of owning a home have soared. Across America, climate change, rising home prices, and other factors are accelerating the costs of property insurance – and to a lesser extent property taxes and utilities. As those variable costs increase, they’re grabbing an increasing share of the monthly housing budget, a report out Monday shows.

“Variable costs like taxes and insurance now make up nearly one-third of the average mortgage payment nationwide,” said Andy Walden, vice president of research and analysis at data provider ICE. “For borrowers in more risk-prone areas and areas with higher property taxes, variable costs make up nearly half of the average borrower’s monthly payments, and that’s before you factor in other variable costs of homeownership, like electricity, water, and transportation.”