Roofing Terms Explained:
13 FAQs + Glossary

Roof underlayment is a waterproof or water-resistant barrier installed directly on top of your roof deck (plywood or OSB), beneath the shingles or other roofing material. It serves as a secondary line of defense against water if shingles are damaged or blown off. There are three types: felt (tar paper) at $0.10-$0.25/sqft, synthetic at $0.15-$0.50/sqft, and ice and water shield (self-adhering) at $0.50-$1.50/sqft. In Charlotte NC, building codes require ice and water shield in valleys, around penetrations, and at eaves. Quality underlayment prevents leaks, extends roof life, and is required for most manufacturer warranty coverage.

Roof flashing is thin sheet metal (aluminum, galvanized steel, or copper) installed at joints and transitions where the roof meets a vertical surface or where water would otherwise penetrate. Flashing is needed at: chimneys (step flashing and counter flashing), skylights, roof-to-wall transitions, valleys where two roof planes meet, around vent pipes and HVAC curbs, and at the drip edge along eaves and rakes. Flashing failure is the number one cause of roof leaks. Quality flashing costs $5-$15 per linear foot installed. Charlotte NC building codes require flashing at all penetrations and transitions.

Roof warranties come in three types. Manufacturer material warranty covers defects in the roofing material itself (typically 25-50 years for shingles, limited lifetime for metal). Manufacturer system warranty covers materials and labor when the entire roof system uses one manufacturer's products and is installed by a certified contractor (GAF Golden Pledge and CertainTeed SureStart Plus offer the best coverage). Workmanship warranty is provided by your roofing contractor and covers installation errors (typically 5-25 years). Best Roofing Now provides a 10-year workmanship warranty plus extended manufacturer coverage through our GAF and CertainTeed certifications.

Common actions that void roof warranties include: improper installation by a non-certified contractor, installing satellite dishes or antennas that penetrate the roof without proper sealing, walking on the roof excessively or with improper footwear, power washing shingles (strips granules), failing to maintain proper attic ventilation, neglecting routine maintenance and inspection, having unlicensed contractors make repairs, installing incompatible materials (mixing manufacturer systems), and making unauthorized modifications. To protect your warranty, always use a certified contractor for any roof work, keep maintenance records, and schedule regular professional inspections.

A roofing square is the standard unit of measurement in the roofing industry, equal to 100 square feet of roof area. Contractors price materials and labor per square. For example, if a roofer quotes $350 per square for architectural shingles, that means $350 for every 100 square feet. A typical Charlotte NC home has 20-25 squares (2,000-2,500 square feet of roof area). To calculate your roof squares, multiply the footprint of your home by a pitch multiplier (1.0 for flat to 1.4 for steep). Three bundles of standard shingles cover one square.

Roof pitch is the slope of your roof expressed as a ratio of vertical rise to horizontal run. A 6:12 pitch means the roof rises 6 inches for every 12 inches of horizontal run. Pitch matters because it determines: which roofing materials can be used (shingles require minimum 2:12, some materials require 4:12), labor costs (steeper roofs require more safety equipment and take longer), drainage performance (steeper slopes shed water faster), and attic space. Most Charlotte NC residential roofs have pitches between 4:12 and 8:12. Steeper pitches above 8:12 cost 15-25% more to roof due to increased labor difficulty.

Attic ventilation is the system of intake vents (soffit vents) and exhaust vents (ridge vents, gable vents, or turbines) that allows air to flow through your attic space. Proper ventilation is critical because it: removes trapped heat in summer (reducing cooling costs by 10-15%), prevents moisture buildup that causes mold, rot, and ice dams, extends shingle lifespan by preventing heat-related deterioration, and is required by building codes and for warranty coverage. The standard ratio is 1 square foot of ventilation per 150 square feet of attic floor. Charlotte NC's hot, humid climate makes adequate ventilation especially important.

Roof decking (also called sheathing) is the flat surface of plywood or oriented strand board (OSB) panels nailed to the rafters, onto which underlayment and shingles are installed. When a roofer says decking needs replacement, it means the wood panels have deteriorated from water damage, rot, or age and can no longer hold nails or support the roofing material safely. Decking replacement adds $2-$5 per square foot (or $1,000-$4,000 for an average Charlotte home) to the project cost. Standard decking is 7/16-inch OSB or 1/2-inch plywood. Your roofer cannot fully assess decking condition until the old roof is removed.

A tear-off involves removing all existing roofing material down to the decking before installing new roofing. An overlay installs new shingles directly over the existing layer. Tear-offs cost $1,000-$3,000 more due to labor and disposal but are almost always recommended because they allow inspection of the decking, provide a flat surface for proper installation, weigh less (important for structural integrity), and comply with most building codes that limit roofs to two layers. Charlotte NC code allows a maximum of two shingle layers. An overlay may save money short-term but can hide damage and shortens the new roof's lifespan.

Drip edge is an L-shaped metal strip installed along the eaves and rakes (gable ends) of a roof. It directs water away from the fascia and into the gutters, preventing water from wicking back under the shingles and rotting the roof edge. Drip edge is required by the International Building Code and by Charlotte NC building codes for all new roof installations. It is also required for GAF and CertainTeed extended warranty coverage. Drip edge costs $1-$3 per linear foot installed. Using color-matched drip edge creates a clean, finished appearance along your roofline.

Ridge caps are specially designed shingles that cover the peak (ridge) of your roof where two sloping planes meet. Unlike regular field shingles that lie flat, ridge caps are pre-bent or can be folded over the ridge to create a watertight seal at this vulnerable point. Ridge cap shingles are thicker and stiffer than field shingles to withstand higher wind exposure at the peak. They come in matching colors and add a finished dimensional look. Hip and ridge cap bundles cost $30-$80 each and cover 20-33 linear feet. Using manufacturer-specific ridge caps (not hand-cut field shingles) is required for full warranty coverage.

Soffit vents are the intake ventilation openings located in the underside of your roof overhang (the soffit). They allow fresh outside air to enter the attic at the lowest point, which then rises and exits through the ridge vent or other exhaust vents at the top. This continuous airflow is essential for regulating attic temperature and moisture. Without proper soffit ventilation, hot air gets trapped in summer (causing shingle deterioration) and moisture builds up in winter (causing mold and rot). Soffit vents should never be blocked by insulation. In Charlotte NC, continuous soffit vents provide the best performance for our humid climate.

A roof valley is the V-shaped channel formed where two sloping roof planes meet at an inside angle. Valleys are the highest-traffic water channels on your roof, concentrating and directing large volumes of rainwater during storms. Because of this high water volume, valleys require special waterproofing: ice and water shield membrane applied from the center 18-36 inches in each direction, metal valley flashing or woven/closed-cut shingle techniques, and careful installation to prevent water from being diverted under shingles. Valley failures are among the most common leak sources. In Charlotte NC's heavy rain climate (43 inches annually), proper valley construction is critical.