With contractors and repairmen in short supply, many homeowners are turning to do-it-yourself videos, with mixed results.

“There’s a certain type of lumber you have to use for an exterior project, and if you aren’t using rot-resistant lumber, the right nails, the right bolts, it will cost you more,” said Scott Savel, an Elgin carpenter who specializes in restoring vintage porches. “When you’re talking about anything that’s structural, you really need to assess your confidence.”