“At the end of the project, you’re a hero,” Mr. Vila said.

Four decades after Mr. Vila and the rest of the original “This Old House” crew introduced viewers to the concept of watching contractors turn tired homes into pretty ones, knocking down walls is big entertainment. “This Old House” is a powerful brand with a magazine, a website and a spinoff, “Ask This Old House.”

The show’s creator, Russell Morash, whose credits include “The French Chef” with Julia Child and “The Victory Garden,” was crowned the “father of how-to television” by the National Academy of Television Arts & Sciences when it awarded him a lifetime achievement Emmy in 2014. His brand of educational television paved the way for a genre of reality TV centered around what would otherwise be mundane tasks.

Now the competition is stiff. Renovation-hungry viewers can tune in 24 hours a day to HGTV’s endless loop of angst-ridden shows, including “Love It or List It” and “Flip or Flop.” Other networks, including Bravo, have their own high-drama renovation lineups, with shows like “Buying It Blind” and “Flipping Exes.”

But “This Old House” didn’t originally follow the formula of the anxious homeowner saved by a crew of knowledgeable tradesmen that has come to define the genre. Its first season, which aired on WGBH Boston, a local public television station, had no homeowner at all. Instead, it chronicled the restoration of a vacant and dilapidated Victorian house in Dorchester, Mass., that the station bought and later sold. PBS picked up the unlikely hit show the following season, and in 1982, producers featured a homeowner restoring a Greek Revival house in Arlington, Mass. After that, the formula took hold.

To find the right house, the show accepts proposals from homeowners, architects and builders, selecting homes based on the scope of work, budget, timing, style and location. (Mr. Vila said that Mr. Morash particularly liked houses in warmer places, like Santa Barbara, Calif., where a winter spent on location would be more appealing than in cold New England.)