A roof system can be installed on a new or existing building. Roofing a new building is called new construction. An entire roof assembly is installed from the deck up.

When a roof system is installed on a build-ing that already has a roof, it is called reroofing

Sometimes, a new roof membrane can be installed over an existing one. This is called a re-cover. A new membrane is installed on top of the existing one after the surface is prepared.

New Construction Installing a roof system on a new building. Reroofing Installing a new roof system on a building that is not new. Re-cover Installing a new roof system on top of an existing roof system. Tear-off Removing an existing roof system.

When an existing roof system has to be removed, it is called a tear-off (see picture). Equipment and machinery can usually be used to help with this kind of work.

The old material can be thrown away. Sometimes, a deck needs to be repaired before a new roof system is installed.