You’ll should increase flashing in areas in which you will find peaks or valleys in your roof line, such as all-around chimneys or dormers. Use metal flashing, and seal it with caulk to avoid leaks. Don’t overlook to nail it securely set up, or it is going to eventually slip down to reveal the wall. Check out this text for more on installing

As you arrive at a peak, develop a ridge cap or vent. This is the ultimate contact for a completely waterproof roof.  Another phase is to set up felt paper, which captures humidity in between the shingles as well as the sheathing. Tack down the paper with both a stapler or roofing nail each individual foot, then overlap the felt sheets by four