Roofing glossary
Plain-language definitions for the terms you will encounter when researching a roof replacement, filing a storm claim, or reading a contractor estimate. Organized by category — use the jump links below to find what you need.
Glossary
General roofing
- Decking / Sheathing
- The structural panel layer nailed directly to the rafters — typically 7/16" or 1/2" OSB or plywood. Everything else on your roof sits on top of it. Damaged or soft decking found during tear-off is replaced before new underlayment goes down. Condition of the decking affects both the job timeline and the final invoice.
- Drip edge
- An L-shaped metal strip installed along the eave and rake edges of the roof. It directs water away from the fascia and into the gutter, preventing wicking under the shingle. Minnesota code requires drip edge at all eave edges. It is installed before underlayment at the eave and over underlayment at the rake.
- Eave
- The lower horizontal edge of the roof that overhangs the exterior wall. In Minnesota, eaves are the first surface ice dams form on — water backs up behind the dam, sits on the eave, and can work under shingles into the wall cavity. Ice-and-water shield extends from the eave up past the heated wall line to prevent interior damage.
- Fascia
- The vertical board running along the roofline at the eave, directly behind the gutter. Fascia is often the first wood to rot when gutters fail or ice dams leak — water pools behind gutters and saturates the board. We inspect fascia during every estimate; rotted sections must be replaced before re-roofing to give the drip edge a sound nailing surface.
- Flashing
- Sheet metal (typically galvanized steel or aluminum) installed at every penetration and transition point — chimneys, skylights, pipe boots, dormers, and wall-to-roof junctions. Flashing is the most common source of roof leaks when it fails. A complete re-roof includes replacing all flashings, not just the surface shingles.
- Gable
- The triangular section of an exterior wall between the two sloping sides of a roof peak. A gable roof has two sloping planes meeting at a ridge; a hip roof has four. Gable ends require rake flashing and are more exposed to wind-driven rain than hip ends. Gable vents are a common — though often undersized — ventilation approach on older Minnesota homes.
- Hip roof
- A roof with four sloping sides, all meeting at a central ridge or point, rather than two sides meeting at a peak with vertical gable ends. Hip roofs are more wind-resistant than gable designs and common on ranch-style homes across the Twin Cities Metro. All four edges require hip cap shingles and step flashing where the roof meets any vertical wall.
- Pitch / Slope
- The steepness of a roof, expressed as rise-over-run: a 6/12 pitch rises 6 inches for every 12 inches of horizontal run. Pitch affects material cost (steeper roofs require more labor), walkability during installation, and how well snow sheds in winter. Pitches below 2/12 require modified installation methods; pitches above 9/12 require additional safety rigging.
- Ridge
- The horizontal peak where two roof planes meet at the top. The ridge is the highest point on the roof and the exit point for attic heat and moisture when a ridge vent is installed. Ridge cap shingles or a ridge vent cover are applied here as the final step in installation. A proper ridge assembly is essential for balanced attic ventilation.
- Rake
- The sloped edge of a gable roof running from the eave up to the ridge peak — the diagonal edge, as opposed to the horizontal eave. Rake edges require drip edge and are nailed differently than field shingles to resist wind uplift. In high-wind areas, starter strip is also applied at the rake for additional adhesion.
- Soffit
- The underside of the roof overhang, between the fascia and the exterior wall. Vented soffits allow outside air to enter the attic from below the roof deck, which is the intake half of a balanced ventilation system. Many older Minnesota homes have solid wood soffits with no ventilation — a factor in ice dam formation and premature shingle failure.
- Square (roofing unit)
- 100 square feet of roof surface — the standard unit contractors use for estimating materials and labor. A typical 1,800 sq ft ranch home may have 20–24 squares of roof surface depending on pitch and overhangs. Shingles are sold by the bundle; three bundles cover one square for standard architectural shingles. Your estimate will list the job size in squares.
- Valley
- The V-shaped channel where two roof planes meet and slope downward. Valleys concentrate runoff from two roof surfaces into one channel, making them a high-risk area for leaks. Minnesota code requires a continuous run of ice-and-water shield in all valleys before underlayment and shingles are applied. Closed-cut and open valley styles have different maintenance profiles.
- Underlayment
- A water-resistant layer installed directly on the decking, under the shingles. Standard underlayment is synthetic felt (15 or 30 lb equivalent); heavier synthetic products are common in Minnesota for added protection during the installation window before shingles go on. Underlayment is the last line of defense if shingles are damaged in a storm.
- Ice-and-water shield
- A self-adhesive membrane that bonds directly to the decking and seals around fasteners, providing a waterproof barrier at the most leak-vulnerable areas of the roof. Applied at eaves, valleys, and penetrations. Minnesota code requires a minimum 24-inch run inside the heated wall line at all eaves — for most homes this means 36–48 inches of coverage from the eave up.
Glossary
Shingles and materials
- Architectural shingle
- A multi-layer asphalt shingle with a dimensional, textured appearance — thicker and heavier than a three-tab. Architectural shingles are the standard for residential re-roofs in Minnesota. They carry 25–30 year performance ratings and better wind resistance than three-tab (commonly rated to 130 mph vs. 60–70 mph for three-tab). Most of the asphalt we install is architectural.
- Three-tab shingle
- An older, single-layer asphalt shingle with three uniform cutouts giving a flat, tile-like appearance. Three-tab shingles are lighter and less wind-resistant than architectural. They are still available but rarely specified on new installations — most manufacturers have phased them out or offer limited product lines. If your existing roof is three-tab, replacement will almost certainly go to architectural.
- Laminated shingle
- Another term for architectural or dimensional shingles — named for the lamination process that bonds two asphalt layers together to create the dimensional look. The terms laminated, architectural, and dimensional are interchangeable in most contexts. All GAF Timberline products are laminated shingles.
- SBS-modified asphalt
- Asphalt modified with styrene-butadiene-styrene (SBS) rubber — a polymer that makes the base asphalt more flexible in cold temperatures and more elastic under thermal stress. SBS shingles are worth considering in Climate Zone 6/7 where temperature swings between −30°F and +90°F are common. Some premium shingle lines use SBS modification in the adhesive strip.
- Standing seam metal
- A metal roofing system where panels run vertically from eave to ridge, with raised seams that interlock and are mechanically fastened — fasteners are never exposed to weather. Typical panel widths run 12–18 inches. Lifespans of 40–60 years are realistic in Minnesota with proper installation. Cost runs $12–$18 per square foot installed versus $4.50–$6.50 for asphalt. Standing Seam Metal details
- Exposed-fastener panel
- A metal panel system where screws penetrate through the panel face directly into the decking — fasteners are visible on the finished roof. Less expensive than standing seam but requires periodic fastener inspection and washer replacement as rubber seals age. More common on outbuildings and agricultural structures than on residential homes in Minnesota.
- Natural slate
- A natural stone roofing material quarried in slabs and split to thickness — typically 3/16" to 1/4". Slate roofs can last 75–150 years and are fire-resistant. They are heavy: a slate roof may weigh 700–1,500 lbs per square versus 230–430 lbs for asphalt, so structural assessment is required before installation. At $25–$45 per square foot installed, slate is a generational investment. Natural Slate details
- Cedar shake
- Split or hand-sawn wood shingles, typically western red cedar, with a natural look that weathers to silver-gray. Cedar requires retreatment every 5–7 years and is vulnerable to moss and lichen in shaded areas. In Minnesota, ice dam management on cedar needs more care than on asphalt or metal. Cedar is durable when maintained — neglected cedar decays faster than neglected asphalt. Cedar Shake details
- TPO
- Thermoplastic polyolefin — a single-ply membrane used primarily on low-slope and flat roofs. TPO sheets are heat-welded at seams for a watertight joint. Common on commercial roofs and low-slope residential additions. This term appears in estimates when a flat-roof section or porch roof is part of a larger re-roof scope.
- EPDM
- Ethylene propylene diene monomer — a synthetic rubber membrane used on flat and low-slope roofs. EPDM is glued or ballasted (held down with gravel) rather than heat-welded. Durable and cold-weather flexible, but seams require maintenance over time. Like TPO, primarily a commercial or flat-addition material — not used on standard residential sloped roofs.
- Granules
- The crushed stone or mineral aggregate embedded in the surface of asphalt shingles. Granules protect the asphalt from UV degradation, add fire resistance, and give shingles their color. Granule loss accelerates after hail impact — a fresh hail event knocks granules loose, exposing asphalt to UV and shortening the shingle's remaining life. Granule accumulation in gutters is a normal end-of-life indicator.
- GAF Timberline HDZ
- GAF's flagship architectural shingle — the most widely installed asphalt shingle in North America. Features StrikeZone nailing area for consistent placement, LayerLock technology for wind resistance up to 130 mph, and Advanced Protection polymer-modified asphalt for cold-climate flexibility. Carries a 50-year Lifetime Limited warranty when installed by a certified contractor. GAF Timberline HDZ details
Glossary
Installation
- Tear-off
- The removal of existing roofing materials down to the bare decking before new materials are installed. Most re-roofs in Minnesota are full tear-offs — adding a second layer of shingles on top of an existing layer is permitted in some jurisdictions but limits future inspections, adds weight, and voids many manufacturer warranties. We price all jobs as full tear-offs unless code allows overlay and the existing deck is confirmed sound.
- Starter strip
- A pre-cut adhesive shingle installed along the eave and rake edges before the first course of field shingles. The starter strip seals the leading edge of the first shingle row against wind uplift and provides adhesive contact where field shingles would otherwise overhang open air. Skipping the starter strip is a common shortcut that causes early edge failures — all our installations include it.
- Field shingle
- Any shingle installed in the main body of the roof, as opposed to the starter strip, ridge cap, or hip caps. Field shingles are installed in overlapping courses from eave to ridge, with each course offset by half a shingle from the one below to prevent aligned joints. Proper offset and nail placement are the two variables most affecting long-term shingle performance.
- Step flashing
- Individual L-shaped metal pieces installed one per shingle course at the junction of a sloped roof surface and a vertical wall — along dormers, chimneys, and skylights. Each piece overlaps the one below it, creating a stepped waterproof barrier. Step flashing works in tandem with counter flashing above it. Failed step flashing is one of the most common causes of interior wall leaks.
- Counter flashing
- Metal flashing embedded into mortar joints or attached to a vertical wall surface and bent down over the top of step flashing to cap it. Counter flashing prevents water from getting behind the step flashing from above. On brick chimneys, counter flashing is cut into the mortar and sealed with urethane. It is replaced on every re-roof where brick or masonry meets the roof deck.
- Pipe boot / Collar
- A pre-formed rubber or metal flashing that seals the base of a pipe or vent stack where it penetrates the roof. Rubber pipe boots last 10–15 years in Minnesota conditions before UV and thermal cycling crack the rubber at the pipe neck — they commonly fail years before the surrounding shingles. We replace pipe boots on every re-roof; failing to do so leaves an active leak source under new shingles.
- Ridge cap
- Shingles or a pre-formed profile installed along the ridge to cap the joint between the two roof planes. Ridge cap shingles are thicker and pre-bent to fold over the ridge. They can be matched to field shingles or contrasted for visual effect. Ridge cap installation is also where a high-profile ridge vent is integrated when the ventilation system calls for it.
- Hand-nailing vs. pneumatic nailing
- Shingles can be fastened by hand (hammer and nail) or with a pneumatic nail gun. Both methods produce code-compliant results when done correctly. Pneumatic nailing is faster; hand-nailing allows the installer to feel fastener depth more precisely. The risk with pneumatic nailing is over-driven or under-driven nails if the gun pressure is not calibrated. We calibrate guns at the start of each job and spot-check throughout.
- Rafter baffle
- A rigid channel installed between rafters at the eave end to maintain an air space between the insulation and the roof decking. Baffles prevent blown-in or batt insulation from blocking soffit vent intake. Without baffles, insulation migration eliminates the ventilation pathway, traps moisture in the deck, and accelerates rot. Baffles are standard on any job where we open the attic space.
- Net free area (ventilation)
- The actual open area of a vent through which air can move, measured in square inches. NFA is lower than the vent's physical size because frames, mesh, and louvers reduce airflow. Attic ventilation code (IRC R806) requires 1 sq ft of NFA per 150 sq ft of attic floor area, split roughly 50/50 between intake (soffit) and exhaust (ridge). Undersized NFA is the root cause of most ventilation-related roof failures.
- Ridge vent
- A continuous or segmented vent installed along the entire ridge of the roof to allow hot, moist attic air to exhaust at the peak. Works in combination with soffit intake vents to create a continuous airflow path from eave to ridge. A properly sized ridge vent paired with unobstructed soffit intake is more effective than gable vents at uniform attic temperature and moisture control.
- Soffit vent
- A vent cut into the soffit panel allowing outside air to enter the attic at the lowest point of the roof overhang. Soffit vents are the intake half of a balanced attic ventilation system. They must be kept clear of insulation inside the attic (via rafter baffles) to function. Continuous soffit vent strip products provide more NFA per linear foot than individual circular punch vents.
Glossary
Minnesota-specific
- Ice dam
- A ridge of ice that forms at the eave when heat escaping from a poorly insulated attic melts snow on the upper roof. That meltwater runs down to the cold eave, refreezes, and backs up behind the ice ridge. Water pooling behind the dam works under shingles and into the wall cavity. Prevention requires adequate attic insulation (R-49 minimum in Zone 6) and continuous ridge-to-soffit ventilation. Ice Dam Remediation details
- Freeze-thaw cycle
- The repeated process of water entering a crack or seam, freezing and expanding, then thawing — each cycle widening the gap slightly. In north-central Minnesota, freeze-thaw cycles occur 60–100 times per year. They accelerate granule loss on aging shingles, crack dried-out pipe boot rubber, loosen step flashing, and cause mortar joint deterioration around chimneys. Roofing materials rated for Zone 6/7 are formulated to withstand this cycling.
- Frost depth (MN 42–60 inches)
- The depth to which the ground freezes in a typical Minnesota winter — 42 inches in the Twin Cities Metro and up to 60 inches in northern counties. Frost depth does not directly affect roof installation but matters for any structural work involving ground-level attachment points (fascia anchors, gutter hangers in frost-heave zones). We schedule structural ground-contact repairs in fall or after spring thaw.
- Hail corridor
- An informal term for the geographic band in Minnesota that experiences the most frequent large-hail events. The corridor runs roughly from the Iowa border northeast through the Twin Cities and up through the Brainerd Lakes area. Hail events producing 1-inch or larger stones — the typical threshold for insurance claim eligibility — occur in any given location within this corridor roughly 3–5 times per decade.
- Ice-and-water shield eave requirement (MN code)
- Minnesota Building Code requires ice-and-water shield to extend from the eave edge to a point at least 24 inches inside the heated wall line — not just to the exterior wall. For most homes with standard 12-inch overhangs, this means 36–48 inches of membrane from the eave up the slope. The interior wall measurement is what matters, not a fixed linear distance from the edge.
- Snow load
- The weight of accumulated snow that a roof structure must support without failure. Minnesota ground snow loads range from 35 psf in the Twin Cities to 50+ psf in northern counties. Roof structural design accounts for snow load; roofing materials themselves are secondary to the framing. Wet spring snow is denser than dry winter snow — a single heavy snowfall can deposit 15–20 lbs per square foot on a flat roof.
- MN Climate Zone 6/7
- The IECC climate classification for most of Minnesota. Zone 6 covers the Twin Cities Metro and central regions; Zone 7 covers northern Minnesota. Zone designations determine minimum attic insulation requirements (R-49 for Zone 6, R-60 for Zone 7), ventilation calculations, and the applicability of certain code requirements. Material manufacturers publish installation guidance specific to Zone 6/7 conditions.
- §325E.66 (deductible waiver prohibition)
- Minnesota Statute 325E.66 prohibits roofing contractors from waiving, absorbing, rebating, or paying a homeowner's insurance deductible as an inducement to hire them. Any contractor offering to cover your deductible is violating Minnesota law — the practice constitutes insurance fraud. The prohibition applies to the contractor; your obligation to pay your deductible is between you and your insurer.
Glossary
Insurance and storm damage
- ACV (Actual Cash Value)
- A settlement method in which the insurer pays the replacement cost of damaged materials minus depreciation. If your 15-year-old shingles have a 25-year rated life, the insurer calculates that 60% of the value has already been consumed and pays 40% of replacement cost. ACV settlements may not cover the full cost of your roof replacement. Check your policy — many offer an RCV endorsement.
- RCV (Replacement Cost Value)
- A settlement method in which the insurer pays the full cost to replace damaged materials at today's prices, without subtracting depreciation. RCV policies typically release payment in two stages: an initial ACV check at claim approval, and a recoverable depreciation check after the replacement work is completed and invoiced. RCV coverage costs more in premiums but eliminates out-of-pocket exposure beyond your deductible.
- Depreciation
- The reduction in value the insurer applies to materials based on age and expected remaining life. Depreciation is the difference between RCV and ACV. Under an ACV policy, depreciation is non-recoverable — you absorb it. Under an RCV policy, depreciation is held back by the insurer and released once the work is completed. Depreciation schedules vary by insurer; asphalt shingles typically depreciate over 20–25 years.
- Scope of loss
- The adjuster's written itemization of all damaged components and the cost to repair or replace them. The scope of loss is the document that drives your claim payment. We review it carefully — scope errors (missed items, wrong square footage, omitted accessories) are common and can be corrected through a supplemental claim before work begins.
- Supplement claim
- An additional claim submission filed after the initial scope of loss to capture items the adjuster missed or undervalued. Common supplement items include ice-and-water shield, drip edge, pipe boots, ridge vents, and steep-slope labor adders. We document and submit supplements on your behalf at no additional charge — the goal is to align the insurer's scope with the actual work required. Storm damage claim walkthrough
- Deductible
- The amount you pay out-of-pocket before insurance coverage applies. If your roof replacement costs $14,000 and your deductible is $2,500, the insurer pays $11,500 (on an RCV policy, before depreciation). Your deductible is a contractual obligation to your insurer — no contractor can legally waive it in Minnesota (see §325E.66). We can separate deductible costs from insurance-covered work on the invoice for financing purposes.
- Public adjuster
- A licensed professional who represents the homeowner — not the insurer — in documenting, negotiating, and settling a claim. Public adjusters work on contingency (typically 10–15% of the claim settlement). For most standard storm claims, a contractor with strong documentation can achieve comparable results without the fee. For large, multi-system claims or disputed denials, a public adjuster may recover more than their fee costs.
- Hail bruising
- Impact marks left on soft metal surfaces — gutters, downspouts, flashing, AC condenser fins, and plumbing vents — when hailstones strike. Adjusters examine soft metals because they show impact marks more clearly than asphalt shingles, confirming that a hail event occurred and reached the property. Bruising on soft metals without shingle damage typically indicates sub-threshold hail; bruising with granule loss confirms claim-eligible damage.
- Soft metals
- The deformable metal components on and around a roof that record hail impact — gutters, downspouts, aluminum fascia wraps, flashing, plumbing vent caps, and AC fins. Adjusters and contractors both inspect soft metals first when assessing potential hail damage. Circular impact dents on multiple soft metal surfaces, combined with directional granule loss on shingles, is the standard documentation pattern for a hail claim.
- Wind uplift
- The force wind exerts on a roof surface, lifting rather than pushing. Wind pressure creates negative pressure (suction) on the leeward and upper-roof surfaces, pulling shingles and panels upward. Shingles are rated by wind resistance — most architectural shingles are rated to 110–130 mph when properly fastened. The eave edge, ridge, and rakes are most vulnerable to uplift; starter strip and proper nail placement are the defenses.
Glossary
Warranties and licensing
- Workmanship warranty
- A warranty issued by the installing contractor — not the manufacturer — covering defects in installation for a specified period. If a flashing leak or improperly sealed valley causes damage two years after installation, the workmanship warranty covers the repair. Terms vary widely by contractor: one-year warranties are common but short; reputable contractors offer 5–10 years. Our workmanship warranty terms are stated on the contract before you sign.
- Material warranty (manufacturer)
- A warranty issued by the shingle or panel manufacturer covering defects in the product itself — delamination, premature granule loss, manufacturing flaws. Material warranties are separate from workmanship warranties and are voided by improper installation. GAF's Lifetime Limited warranty requires installation to GAF specifications by a registered contractor. Always verify your installer is registered with the manufacturer.
- GAF System Plus warranty
- GAF's enhanced warranty tier available to certified Master Elite contractors. System Plus requires installing a complete GAF system — shingles, underlayment, starter, ridge cap, and leak barrier — all from GAF product lines. In return, GAF backstops the contractor's workmanship warranty up to the coverage limits, giving homeowners recourse if the contractor closes. Not all contractors qualify; we are a registered GAF installer.
- Lifetime limited warranty
- A warranty marketed as "lifetime" but subject to defined limitations — typically prorated coverage after the first 10–25 years, and sometimes transferable to one subsequent owner. Read the limitations: "lifetime" refers to the product's rated service life, not the homeowner's lifetime. GAF's Lifetime Limited warranty on Timberline HDZ provides non-prorated coverage for the first 50 years under qualifying conditions.
- MN DLI residential contractor license
- A license issued by the Minnesota Department of Labor and Industry (DLI) required to contract for residential construction work over $15,000. Roofing contractors are required to hold this license. Unlicensed contractors cannot legally pull permits, may not be bonded, and leave homeowners with limited legal recourse. Verify any contractor's license at the DLI website before signing a contract. Our license number is on our contract header.
- Certificate of insurance
- A document issued by an insurance carrier confirming that a contractor carries active general liability and workers compensation coverage. Request a certificate before work starts — it should name your property address and list the contractor as the insured. If a worker is injured on your property and the contractor lacks workers comp, you may be liable. We provide certificates on request.
- 1099 subcontractor
- A worker paid as an independent contractor rather than a W-2 employee. Many roofing companies crew jobs entirely with 1099 subcontractors, which reduces their payroll tax liability but also means those workers often carry no workers compensation coverage. If an uninsured 1099 worker is injured on your property, the liability question becomes complicated. Ask your contractor how their crew is classified and verify their workers comp certificate covers all on-site workers.
- Workers compensation
- Insurance that covers medical costs and lost wages for employees injured on the job. In Minnesota, employers with one or more employees are required to carry workers compensation insurance. Roofing is a high-risk trade — premium rates reflect that. Contractors without workers comp expose homeowners to potential liability if an injury occurs. A certificate of insurance listing workers comp coverage is a baseline requirement before any crew steps on your roof.
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Request a free inspection and written estimate — we walk through every line item so nothing on the contract surprises you.