LA MALBAIE, Quebec — Ever since Rosaire Tremblay bought a candy-cane-colored house overlooking the St. Lawrence River two years ago, tourists have trampled on his land to photograph the spectacular view, gawk at the beluga whales or reach the imposing Fairmont Le Manoir Richelieu hotel, perched on a nearby cliff.

Then came the fence.

Canada is hosting world leaders, including President Trump, Prime Minister Theresa May of Britain and President Emmanuel Macron of France, starting Friday at a two-day Group of 7 summit meeting in this picture-perfect resort town. The leaders are to discuss, among other things, job creation, gender equality and climate change.

Mr. Tremblay’s house is the only home in town in a high-security “red zone” near Le Manoir Richelieu, where the world leaders will stay. Suddenly, his modest red and white home is protected by a nearly two-mile-long steel security fence affixed with lights and cameras, making it among the most secure and impenetrable fortresses in the country.

Now, Mr. Tremblay, 63, a jovial retired factory owner and avid consumer of political news, has to pass through security checks to get to his own house. And the fancy hotel is off limits, so the best he can hope for is to spot his favorite leader, Chancellor Angela Merkel of Germany, as she flies overhead by helicopter.