Roofing glossary

Knowing these terms is the cheapest form of protection you have. Once you can read a quote, you can tell whether two bids describe the same job — which is where most overpaying happens.

The unit terms matter most. A square is 100 sq ft of roof surface; Fixr prices tear-off and disposal at $50–$150 per square, so the square count drives your bill. Pitch is the vertical rise over a 12-inch horizontal run; steeper pitches cost more in labor and safety equipment.

The assembly terms matter next. Decking (or sheathing) is the plywood or OSB base. Underlayment goes over it as a secondary water barrier. Ice-and-water shield is a self-adhering membrane used at eaves and valleys in cold or wet climates. Flashing is the metal that seals joints at chimneys, walls, valleys and skylights. Drip edge is the metal at the roof edge that directs water into the gutter. Ridge vent is the exhaust vent along the peak, part of the attic ventilation system.

Two process terms: a tear-off strips the old roof to the deck, while an overlay installs new shingles on top of the old ones. They are not interchangeable, and they should never be compared as if they were.

How to choose

Square

100 square feet of roof surface. Your quote's square count is the number to check first — it should be based on a measurement, not your house's floor area.

Pitch

Rise in inches over a 12-inch run, written like 6/12. Steeper roofs cost more to work on and can require additional safety equipment.

Underlayment vs ice-and-water shield

Underlayment covers the whole deck as a secondary barrier. Ice-and-water shield is a self-adhering membrane used in the high-risk areas — eaves, valleys, penetrations.

Flashing

Metal that seals transitions and penetrations. It should be new on a replacement, not reused.

Tear-off vs overlay

Tear-off removes the old roof; overlay covers it. Fixr puts tear-off and disposal at $50–$150 per square, which is most of the price difference between the two approaches.