Do-it-yourselfers, empowered by YouTube videos and well-produced cable TV shows, have no doubt saved themselves serious money by tackling home-improvement projects. But some jobs are better left to the professionals. A good rule of thumb:...

Do-it-yourselfers, empowered by YouTube videos and well-produced cable TV shows, have no doubt saved themselves serious money by tackling home-improvement projects. But some jobs are better left to the professionals. A good rule of thumb:...