Flashing is a good way of preventing water from entering a dwelling at the point where the roof meets the walls. To begin the installation, fold a five-by-seven piece of aluminum flashing lengthwise.

Q. We closed on our house in March 2010, and the first thing we did was install a new asphalt shingle roof. Last fall, when I was cleaning my gutters, I noticed exposed wood/sheathing where the cedar ...