When replacing a roof on an existing home, it is most cost-effective to install a dormer. Dormers have a 6 to 2 advantage on our scorecard, so we believe they are worth the expense and risk, especially if you want to add some visual appeal or more living space to your property. The main advantage of a dormer is that it allows for the installation of additional rooms without having to build from scratch. For example, if you need more sleeping space but don't want to expand into your yard, a dormer can be used instead. Dormers are also useful when you want to create a secondary suite out of one part of the house while still keeping the main portion affordable. For example, a dormer can be used over a bedroom to provide extra storage or a reading nook while still being able to afford other upgrades or repairs to the rest of the house. Finally, a dormer is effective at reducing heating and cooling costs by allowing for more efficient placement of windows and doors. For these reasons, we recommend adding a dormer to any existing roof project. There are several different types of dormers available on the market today. The two most common are gable-end and half-dome. A gable-end dormer has its peak at the same level as the rest of the roof, whereas a half-dome dormer has its peak higher than the rest of the roof.