The Summit Avenue mansion that has been home to 11 Minnesota governors is about to get a nearly $6.3 million renovation, forcing out Gov. Tim Walz's family until late next year.

Plans to overhaul the 111-year-old governor's residence have been in the works for more than a decade. The English Tudor-style home is slated for exterior repairs along with upgrades to its mechanical, electrical, plumbing and security systems, and more.

Construction is expected to start in June and take more than a year. During that time the state will pay about $330,000 to lease a house for the Walz family in Sunfish Lake, just south of West St. Paul in Dakota County, according to the lease documents.

Finding a suitable rental home for the governor's family that is close enough to the State Capitol and can accommodate security needs "is obviously an expensive thing to do," said Wayne Waslaski, an assistant commissioner at the Department of Administration, the state entity leasing the home.

The state is renting the home from former Republican U.S. Senate candidate Michael McFadden, an unlikely twist that was first reported by Minnesota Public Radio News.

"It's going to help facilitate taking care of a pretty significant state asset," said Waslaski. "So that a property that is on the National Register [of Historic Places] is maintained and preserved and it will be around for the next 50, 60, 70 years plus."

McFadden is a businessman who challenged former U.S. Sen. Al Franken in 2014. He could not be reached for comment Monday.

Waslaski said the department sent out a request for information to real estate industry professionals and searched online with little luck. Calls to industry contacts eventually led them to McFadden's property, he said.

The lease starts Monday and runs through September 2024, with an option to extend it for three more months. Walz's family is expected to move into the five-bedroom, 7,952-square-foot lakeside home in late May.

Monthly rent will be $17,326, the lease document states, and the state will also pay around $15,000 for carpet installation. The Department of Administration has funds in its budget to cover the temporary housing costs and the Legislature doesn't need to take additional action, Waslaski said.

According to a statement from the governor's office, Walz "is grateful to the community of Sunfish Lake for welcoming him and his family" as the governor's residence undergoes renovation.

Exterior tuck-pointing on the governor's residence in St. Paul is expected to start in June or July with full construction underway by September, according to the state's request for proposals (RFP) for a construction manager.

That RFP in December described the scale of work planned for the mansion. The house has seven bedrooms, nine bathrooms and eight fireplaces. It was built for St. Paul lumberman Horace Hills Irvine, whose family donated it to the state in 1965.

"Many of the building components and systems are beyond their life expectancy and therefore have become dilapidated to the point where they must be replaced," according to the RFP.

Planned upgrades include modernizing mechanical systems, replacing plumbing fixtures, revitalizing the building interior and bringing security systems up to current standards.

Repairs also are needed to address site drainage, foundation and tunnel leaks and issues with the carriage house and storage building on the property, according to the RFP.

And there will be some floor plan alternations to improve food service operations, accommodate state-sponsored receptions and improve livability.

"From a maintenance standpoint, it's just getting unreliable. … You have facility staff out there on a pretty constant basis doing repair work," Waslaski said. "You go right down the list of building systems and every one of them is at the point where you just need to do a replacement."