Somerville Beat says the New England home-building gurus shot a segment, called "repairing a cracked floor joist," a few months ago at a 100-year-old home near Magoun Square. The segment will air at various times, depending on your cable company, over the next several days.
The Somerville blog points interested viewers to the "This Old House" online schedule to find air times (enter your zip code, your cable company, and then look for "repairing a cracked floor joist").
You may want to set your TiVo. Or, you can also watch the episode online five days after it originally airs, Somerville Beat points out.