In Parliament this spring, the opposition Conservatives pounced on a government estimate that it cost 1,500 Canadian dollars, or about $1,100, to use government workers to assemble a new play structure for Mr. Trudeau’s children at the prime minister’s official country house, in a park north of Ottawa. (Mr. Trudeau paid the $5,600 for the structure itself out of his own pocket.)

In 1971, the government stopped charging the prime minister rent for lodging, but Mr. Trudeau pays for his food, internet service and a caregiver for his children.

Because the kitchen at Rideau Cottage is meant for a family, not a team of cooks, the kitchen staff for the prime minister still works at the official residence, and the Trudeau family’s meals are driven across the street from 24 Sussex, a practice that has aroused indignation from the Conservatives (whose own party leader lives in an official residence reserved for the head of the opposition).

Mr. Martin, the former prime minister, said the best solution to the 24 Sussex problem would be for Mr. Trudeau to turn over all the decisions about its future to a group of nonpartisan experts.

Still, he welcomed Canadians’ stinginess when it comes to spending money on their politicians.

“I think it’s a good thing,” he said. “When you take a look at the ethical problems that occur around the world, I think the facts that this is something that a Canadian politician would shy away from is really a sign that Canadians do have their ethical priorities in shape.”