Roofing 101

Arnold Roofing Knows that Your Roof Is the Most Important Part of Your Home

Roofing 101 - A guide to how your roofing components work - termsDamage to a roof or an older neglected roof can lead to huge problems that start as leaks and then turn into more costly in-home repairs.

We are experts at preventing roof problems, so check out our Roofing Tips, lingo, and best practices to protecting your home or commercial building.


Built-up Roof- A low-slope (or flat-seeming) roof covered with alternating layers of roofing felt and hot-mapped asphalt and topped off with a layer of gravel.

Cornice- The portion of the roof projecting out from the sidewalls of the house.

Counterflashing- The flashing which is imbedded at its top in a wall or other vertical structure and is lapped down over shingle flashing.

Courses- Horizontal rows of shingles or tiles.

Drip- The strip of metal extending out beyond the eaves or rakes to prevent rainwater from rolling around the shingles back onto the wooden portion of the house.

Eaves- The lower edge of a roof (usually overhanging beyond the edge of the house).

Fascia- Trimboard behind the gutter and eaves.

Flashing- Sheet metal or other material used at junctions of different planes on a roof to prevent leakage.

Felt- The “tar paper” used by roofer, usually made of a combination of asphalt and either paper or rags.

Frieze Board- A Board at the top of the house’s siding, forming a corner with the soffit.

Gable- The triangular upper part of a wall closing the end of a ridged roof

Hip- The external angle at the junction of two sides of a roof whose supporting walls adjoininq.

Joist- In a flat roof, a horizontal structural member over which sheathing is nailed.

Rafter- A structural member (usually slanted) to which sheathing is nailed.

Rake- The slanting edge of a gabled roof extending beyond the end wall of the house.

Ridge- The horizontal line at the top edge of two sloping roof planes.

Sheathing- The rigid material (often 1-inch by 6-inch or one inch by twelve-inch boards or sheets of plywood) which is nailed to the rafters, and to which shingles or other outside roofing materials are secured.

Shingle Flashing- Flashing that is laid in strips under each shingle and bent up the edge of a chimney or wall.

Slope- The number of inches of vertical rise in a roof per 12-inches of horizontal distance. This situation is also referred to as pitch.

Soffit- The boards that enclose the underside of that portion of the roof which extends out beyond the sidewalls of the house.

Square- One hundred square feet of roof, or the amount of roofing material needed to cover 100 square feet when properly applied.

Underlayment- The material (usually roofing felt) laid on top of sheathing before shingles are applied. Valley The less-than 180-degree angle where two sloping roof sections come together. Valley Flashing The flashing in valleys, extending in under to shingles on both sides.