How to tell your roof needs replacing

 1. Places where the roof deck is sagging.
2. Signs of water damage or leaking.
3. Dark spots and trails.
4. Outside light showing through the roof.
5. Check that all bath, kitchen and dryer vents are properly vented outside and not just to the attic. 

Bundle: A package of shingles usually consisting of 19 to 22 shingles, this covers approximately 32 square feet of roof surface.
Condensation: The change of water from vapor to liquid when warm moisture -laden air comes in contact with a cold surface.

Closed Valley: Where ice shield is installed and then shingles are overlapped and cut leaving a nice clean line. (recommended to help prevent ice damage)
Cutout: The open portion of a strip shingle between the tabs.
Deck: The structural base for the roof, this is either made of plywood or plank boards.
Dormer: A vertical opening coming through a sloping roof. 
Downspout: A pipe for draining water from roof gutters.
Drip Edge: A non-corrosive, non-staining material used along the eaves and fascia to allow water run-off to drip clear of the fascia wood and roof deck.
Exhaust Vent: Allows ventilation for the bathroom fans.(connected through a hose in the attic).
Fall Arrest Training: A mandatory training course for anyone wishing to work in roofing and many other areas of construction .
Flange/Pipe, Oatey: Pre-formed flange placed over a vent pipe to seal the roof around the vent pipe opening, also known as bathroom pipe cover
Flashings: A sheet metal used in waterproofing roof penetration where roof deck meets a wall,(there are two types, Dormer and Counter).
Gable: The triangular part of a building's end wall, also a type of roof.
Hip: The outside angle formed by the meeting of two sloping sides of a roof that have their supports running in different directions.
Hip Shingles/Cap Shingles: Shingles used to cover the inclined external angle formed by the intersection of two sloping roof planes.
Ice Back-Up/Ice Dam: Occurs during particular weather patterns of freezing rain, snow and mild to extremely low temperatures. Ice forms at the bottom of downspouts or eaves and builds up to the roof barricading the drainage system, when the snow on the roof melts the water runs into the ice dam and is forced to run horizontally or to pool, often resulting in leaks
Joists: Any of the small timbers or metal beams arranged parallel from wall to wall in a structure to support a floor or ceiling.
Laminated Shingles: Strip shingles containing more than one layer of tabs to create extra thickness, also called three-dimensional shingles or architectural shingles. (recommended).
Mansard/Side Walls: A type of roof in which there are two slopes on each side with the lower slope much steeper than the upper one.
Metal Drip Edge: Narrow strip of non-corrodible metal used at the rake and eave to facilitate water runoff.
Non-cut- Out Shingles: Shingles consisting of a single solid tab with no cutouts
Open Valley: Method of valley construction in which shingles on both sides of the valley are trimmed along a chalk line snapped on each side of the valley, shingles do not extend across the valley, valley flashing is exposed.
Overhang: That portion of the roof structure that extends beyond the exterior walls of a building or structure, typically longer in length then eaves. (2 inches of shingle that hangs into the eaves).
Pitch: The angle steepness of a roof. Rise over the run, e.g. a 4 and 12 roof means that for every 12 horizontal inches, the roof slope rises (goes up) 4 inches.
Ridge: The line of intersection at the top of a roof between opposite slopes or sides.
Ridge Vent: A breathable barrier between the ridge and cap shingles allowing air to vent from the attic through the peak, effective on cathedral ceilings.
Shading: Slight differences in shingle colour that may occur as a result of normal manufacturing operations. 
Square: 100 square feet of roof area.
Starter Strip: Asphalt roofing applied to the eaves that provide protection by filling in the spaces under the cutout and joints of the first course of shingles.
Step Flashing: Flashing application method used where a vertical surface meets a sloping roof plane.
Tab: The portion of a shingle set off by the cutouts, also the part of a shingle that is exposed to the weather.
Three-Tab Shingle: The most popular type of asphalt shingle-usually 12"x 36" in size with three tabs.
Turbine Vent/Whirlybird: A large spinning vent used to provide maximum ventilation, one turbine vent typically provides enough ventilation of two standard vents.
Underlayment: Layer of asphalt-saturated felt (sometimes referred to as tar paper) which is laid down on a bare deck before the shingles are installed, usually along leading edge only.