Summer on the San Francisco Peninsula is beautiful, dry, and predictably sunny. For many homeowners in San Mateo, Palo Alto, or San Jose, this blue-sky window triggers the home improvement bug. When a minor ceiling stain or a few curled shingles are discovered from the previous winter, the temptation to grab a ladder, a tube of roofing cement, and head to the local hardware store for a quick weekend DIY patch is incredibly high. It seems like a cost-effective, proactive...