As homeowners amass a growing mountain of home equity, an estimated 10 million homeowners are expected to take out home equity lines of credit in the next four years, according to a new report from TransUnion.

CNBC reports that in the wake of the housing market crash a decade ago, homeowners have been incredibly conservative with their housing debt.

As home prices have risen, homeowners have remained conservative in tapping their equity, but Transunion says that is about to change and it would be more than double the amount of originations between 2012 and 2016.

Joe Mellman, senior vice president at TransUnion, said some lenders got out of the business because there just wasn’t enough demand. Borrowers simply didn’t have the equity because home values had fallen so far.  Mellman said that even as values rose, borrowers didn’t rush in immediately.

“I think it is some of the hangover. On the consumer side there are some residual feelings.”

As lenders begin to offer a range of new HELOC products that are more attractive to borrowers with lower rates and potentially longer “draw” periods before principal has to be repaid. Mellman said they will face new competition in the market, however, in the form of personal loans made via technology.

“The supply spigot will start to turn up. Fintechs have done a fantastic job innovating their products that younger generations have gotten used to. HELOCs have not seen that innovation.”

Owners are going to use their equity to renovate their homes. As agents deal with a tight housing supply, homeowners have opted to stay put and are going to upgrade their homes. Chris Herbert, managing director of the Joint Center for Housing Studies, said strengthening of the U.S. economy, tight housing inventories, and healthy home equity gains are all working to boost home improvement activity.

“Over the coming year, owners are projected to spend in excess of $330 billion on home upgrades and replacements, as well as routine maintenance.”