It is not uncommon for contractors to include terms you do not understand in your roof replacement estimate. All these are just terms that refer to the services they offer, materials they will use or the work they will do.
Flashing is the use of sheets of galvanized steel or aluminum to prevent water from seeping behind and under structures such as dormers, chimneys, and walls. Flashing prevents water damage to the structure.
This is the primary item on your roof replacement estimate as it includes the actual roofing material the contractor would like to use. The contractor will specify the type of shingles they would like to use, their style, color choice or other options.
The underlayment is also called felt paper and will be the first line of defense against water. It is a protective, waterproof layer that is installed between the shingles and the plywood or roof deck. You might also see fiberglass included beside the underlayment as it improves its waterproofing properties, strengthens it, and makes it easier to install.
Water and Ice Shield
Contractors install these shields to help protect your roof from rain, wind, and ice. They allow proper water drainage and therefore help minimize the risk of water or elemental damage to your roof. These shields adhere to the roof deck and therefore provide additional protection to the underlayment.
The drip edge is a metal strip that is used together with gutters, eaves, and rakes. The drip edge prevents water from getting beneath the shingles and can, therefore, lengthen the lifespan of the roof by adding additional protection from water damage.
Valleys are added where two sloping roof planes meet to aid in providing a pathway for runoff. Valleys are essential to any roofing job and can be used together with shingles or flashing to help the ice and water shield prevent water damage to the roof.
Ridge vents provide ventilation through which moisture escapes and help prevent damage to the roof. Ridge vents are installed along the peak or ridge of a roof to allow hot air to vent out and cool air to come in.
Contractors install a chimney cricket at the back of chimneys on homes with them to prevent the buildup of ice and snow there. They also help divert water away from the chimney.
Fans and pipes
Both of these provide ways for air to escape from the attic or other areas of the house. Some contractors replace them while others keep the existing ones if they are in good condition.
Replacing the gutters is optional but might appear on your estimate if the contractor thinks it is important to replace them or add additional ones.
Sheathing and plywood
Underneath all the layers, there us a decking that forms the solid part of the roof. Note that sheathing and plywood are just two materials that a contractor can use to replace decking, with your estimate varying depending on what alternatives they would like to use.