You'll be able to make advised decisions when hiring a roofing crew if you understand the process, as well as the jargon used in the roofing trade. A moderately-sized, professionally-installed roofing job might take only 3 or 4 days. The overall process followed by the roofing crew goes like this:
Remove all existing shingles, deposit them in a roll-off dumpster: Damaged or old valley flashing and drip edging is also removed at this time. A good crew will use tarps to protect foundation plantings and shrubs during tear-off and will use magnetic tools to pick up nails and metal objects from the lawn.
Make minor repairs on the roof if it is in good condition: If not, replace bad wood with new plywood sheathing or 1 x 6 sheathing boards, whichever is applicable to your type of roof.
Install ice dam protection in regions that require it: The ice guard membrane is a synthetic waterproof barrier material designed to prevent melting ice from backing up under the shingles and penetrating through the sheathing, where the moisture can cause severe damage.
Lay down asphalt roofing paper over the roof sheathing: The layer of roofing paper creates an inner barrier against water penetrating into the house. Rows of roofing paper are overlapped as they progress upward toward the peak, and are normally tacked or stapled in place.
Apply metal drip edging around the edge of the roof, both the eave sides and gable sides: The metal drip edge is nailed in place over the roofing paper or ice guard.
Where necessary, apply a new valley flashing along with areas where two roof planes meet: The valley flashing is typically nailed to the roofing deck and sealed with roofing caulk.
Apply the tab shingles, starting at the eaves and working upward toward the peak: Where roof vents are being installed, these are installed as the progress of the shingles toward the peak.
Apply the flashing around all areas where leaks might come into the house-against the chimney, around skylights and stack vents, etc.: Flashing installation may happen as part of the roofing installation, occurring as the rows of shingles progress upward on the roof deck.
Install the ridge vent: This continuous vent along the peak of the roof will help the air circulation in the attic space and can be integral in exhausting hot air and preventing winter ice dams. Ridge vents may not be included on older roofs, but installing them is a good idea whenever a house is re-roofed. If ridge vents are not practical, the should be other types of roof or gable vents installed to provide air circulation in the attic space.
Complete the final cleanup and haul the debris away: Have the installation inspected and approved by a building inspector.