Roofing Terms, in Plain English

Actual Cash Value, or ACV, is one way an insurance policy can value a roof claim. It pays the cost to replace the roof minus depreciation for its age and wear. In plain terms, ACV reflects what the old roof was worth at the time of the loss, not what a brand-new roof costs. An older roof has depreciated more, so an ACV settlement on it is smaller. Whether your policy pays ACV or full replacement cost is spelled out in your policy.

Algae-resistant shingles are asphalt shingles manufactured with copper or other metal-infused granules that discourage the growth of algae, the organism responsible for the dark streaks and stains that develop on many roofs over time. The metal granules release trace amounts of a compound that is inhospitable to algae as rain washes across the shingle, slowing new growth without eliminating existing stains. They are especially useful in humid, shaded climates where algae streaking is common, and most major manufacturers back the algae-resistant coating with its own limited warranty.

Architectural shingles are asphalt shingles built with two or more layers laminated together, giving them a thicker, dimensional look that mimics the shadow lines of wood shake or slate. The extra layers also make them heavier and more wind- and impact-resistant than a flat, single-layer shingle. They are the standard choice on most new roofs today, valued for their appearance and durability, with manufacturer warranties that commonly run 25 to 50 years.

Attic baffles are rigid channels, usually foam or cardboard, installed at the eave between the rafters to hold a clear air path from the soffit vents into the open attic. Without baffles, loose insulation can slump down and block the soffit intake entirely, choking off the airflow a ridge vent depends on. Baffles are inexpensive and simple to install, but they are also one of the most commonly skipped steps when attic insulation is added or upgraded.

Balanced attic ventilation is a design principle stating that intake ventilation, usually at the soffit, should roughly match exhaust ventilation, usually at the ridge, so air can flow through the attic efficiently in both directions. An attic with plenty of exhaust but too little intake, or the reverse, moves far less air than the total vent area suggests, since the smaller side becomes the bottleneck. Codes and manufacturer guidelines typically specify a target ratio of net free area to attic square footage to achieve it.

Cedar shake is a roofing material made from split or sawn cedar wood shingles, prized for its natural, rustic texture and the way it weathers to a soft silver-gray over time. Hand-split shakes have a rougher, more pronounced texture than machine-sawn cedar shingles, which lie flatter and more uniform. Cedar shake requires more upkeep than asphalt or metal roofing, including periodic treatment and attention to moss and moisture, and its fire resistance depends heavily on whether it has been treated with a fire-retardant coating.

A chimney cricket, also called a saddle, is a small peaked structure built into the roof on the high, or uphill, side of a chimney to divert water around it instead of letting it pool against the back wall. It is often required by code on wider chimneys where a flat, wide swath of roof would otherwise dam water behind the chimney. A cricket is framed and flashed like a miniature roof valley on each side, feeding water around the chimney and back into the main roof slope.

Class 4 impact-resistant shingles are shingles that earned the highest rating, Class 4, in an industry test that drops a steel ball to simulate hail impact. They are built tougher, often with a reinforced backing, so they resist the bruising and cracking that hail causes on ordinary shingles. Because they hold up better in hailstorms, many insurers offer a premium discount for homes that install them, though the discount and terms depend on your insurer and policy.

Counter-flashing is a second layer of metal flashing installed above step flashing or base flashing, usually embedded into a masonry joint on a chimney or wall, that laps down over the top edge of the flashing beneath it. It caps and seals that top edge so water cannot get behind the step flashing from above. Counter-flashing is most often seen wrapped around brick chimneys, where it is cut into the mortar joint and bent down over the roof's step flashing.

Delamination is the separation of a roofing material's bonded layers, most often used to describe plywood or OSB decking coming apart at its internal glue lines after prolonged exposure to trapped moisture. A delaminated panel loses much of its structural strength even while it may still look intact from below, since the separation starts between internal layers rather than on a visible surface. It can also describe laminated shingles losing their bond, though decking delamination is the more serious version, since it undermines the surface everything is fastened to.

A dormer is a small structure that projects out from a sloped roof, with its own roof and usually a window, built to add headroom, light, or space to the floor below. Dormers create extra roof-to-wall seams where they meet the main roof, and those seams need careful flashing to stay watertight. Because a dormer interrupts an otherwise continuous slope, it is one of the more common places an older or poorly flashed roof develops a leak.

Drip edge is a strip of metal flashing installed along the edges of a roof, at the eaves and the rakes, before the shingles. It guides rainwater off the roof and into the gutters instead of letting it run back underneath and soak the fascia and the deck. Drip edge is a small, inexpensive piece, but leaving it out lets water wick into the wood at the most vulnerable edge of the roof, where rot starts.

Dry-in is the stage of a roof installation where the deck is covered with underlayment, and often ice and water shield at the vulnerable areas, making the roof temporarily weatherproof before the shingles go on. Reaching dry-in means the home is protected from rain even though the finished roof is not yet installed, which matters most on new construction and tear-off replacements where the deck sits exposed for a period. A roof left at dry-in too long should still be checked, since underlayment alone is temporary, not permanent.

The eave is the lower edge of a roof that overhangs the exterior wall, running along the horizontal side of the house rather than the sloped gable ends. It is where drip edge, gutters, and the soffit all come together to control water as it leaves the roof. Because rain concentrates and drains off at the eave, it is one of the roof's highest-wear areas. Codes in colder regions require an ice barrier there against ice dams, and in warmer climates quality installations add ice and water shield at the eave by choice.

Emergency tarping is the temporary installation of a heavy-duty waterproof tarp over a damaged section of roof to stop active water intrusion until a permanent repair can be scheduled. It is used after storm damage, a fallen limb, or any sudden roof breach that leaves the deck exposed, and it is meant as a short-term stopgap, not a lasting fix. A properly installed tarp is anchored well beyond the damaged area and secured through the decking rather than weighted down, since wind can tear loose a poorly fastened one.

Exposed-fastener metal roofing is a metal panel system installed with screws driven directly through the panel face into the structure below, each fitted with a rubber washer meant to seal around the screw. It costs less to buy and install than standing seam metal because the panels are simpler and go on faster, but the exposed screws and washers are the system's main weak point, since the washers harden and crack years before the metal itself wears out. Periodic washer inspection is part of maintaining this roof type.

The fascia is the long, straight board that runs along the lower edge of the roof, capping the ends of the rafters where the roof meets the gutters. Gutters are usually mounted directly to the fascia, so it carries their weight and the water they collect. A sound fascia keeps the roof edge looking clean and gives the gutters something solid to hang from, while a rotted fascia can let gutters pull loose and water get behind them.

Felt paper, sometimes called tar paper, is a traditional roofing underlayment made of a base material saturated with asphalt, rolled out across the deck as the water-resistant layer beneath the shingles. It has been used for generations and is typically sold by weight per square, such as 15-pound or 30-pound felt, with the heavier weight offering more tear resistance and durability. Felt paper has largely been replaced by synthetic underlayment on new installations, though it still meets code in most areas and remains a valid, lower-cost option.

Flashing is the thin metal that seals the joints and edges where a roof meets something else, such as a chimney, a wall, a skylight, or a valley. Its job is to direct water away from those seams so it cannot sneak underneath the shingles. Flashing is one of the most important leak-stopping parts of a roof, and most roof leaks start at failed or poorly installed flashing rather than in the open field of shingles.

A flat roof is a roof with a very low slope, often just enough pitch to keep water moving toward drains rather than a slope steep enough to shed it quickly like a conventional shingled roof. True flat roofs are rare, since some minimal slope is needed by design; what people call a flat roof is technically low-slope. Because water lingers on the surface far longer than on a steep roof, flat roofs require a waterproof membrane, such as TPO, EPDM, or modified bitumen, rather than shingles.

A gable roof is the classic triangle-shaped roof style, with two sloped sides meeting at a central ridge and a flat, vertical triangular wall, the gable, at each end. It is simpler and generally less expensive to build and shingle than a hip roof because it has fewer seams and hips. The tradeoff sits at the gable ends themselves, which can be more vulnerable to wind if not properly braced, particularly in exposed locations.

A gable vent is a vent, often louvered and either triangular or rectangular, installed high on the flat wall of a gable end to let hot attic air escape. It is an older style of passive exhaust ventilation, common on homes built before ridge venting became standard, and it can work well on its own or alongside other vents depending on the attic's layout. When a roof is later fitted with a full ridge and soffit vent system, gable vents are sometimes sealed off so the two exhaust paths do not work against each other.

A gambrel roof is a symmetrical, two-sided roof style with two slopes per side, a steep lower slope and a shallower upper slope, most familiar from traditional barn design. The steep lower pitch maximizes headroom and usable floor space in the story beneath it, which is why the style shows up on barns, carriage houses, and some colonial-era homes built to get the most storage or living space out of a given footprint. Its two-slope shape adds a ridge seam at the transition that needs correct flashing to stay watertight.

A gutter apron is a style of drip edge shaped specifically for the eave, with a longer, more sharply bent lower flange designed to extend past the fascia and reach down into the back of the gutter trough. Unlike standard drip edge, which simply directs water off the roof edge, a gutter apron aims that water directly into the gutter, closing the gap where water can otherwise splash or run behind the gutter's back wall. It is installed at the eave only, not along the rake.

Hail bruising is the impact damage hail leaves on an asphalt shingle when it strikes with enough force to crack or displace the mat underneath without necessarily punching all the way through. It typically shows up as a dark, soft, slightly indented spot where granules have been knocked loose, often invisible from the ground and easiest to identify up close during a hands-on inspection. Bruising is treated differently from ordinary wear because it is sudden, storm-caused damage rather than gradual aging, and how it is handled depends on the specific inspection findings and your insurance policy.

A hip roof is a roof style in which all sides slope downward to the walls, with no vertical gable ends. Instead of two triangular walls like a gable roof, a hip roof has four, or more on complex shapes, sloped planes that meet at hips and a ridge. Hip roofs are generally more wind-resistant than gable roofs because of their shape, but they cost more to build and shingle because of their extra seams, hips, and roof area.

Ice and water shield is a self-adhesive, waterproof membrane installed in the most leak-prone areas of a roof, such as valleys, around chimneys and skylights, and along the eaves. Unlike standard underlayment, it sticks directly to the decking and seals tightly around nails, creating a watertight barrier. It is used as added protection in the spots where wind-driven rain and water backup are most likely to force their way under the shingles.

An ice dam is a ridge of ice that forms at the edge of a roof when melting snow refreezes at the colder eave, creating a barrier that traps meltwater behind it. That trapped water can back up under the shingles and leak into the home, since shingles shed water flowing downhill, not water pooling and pushing uphill against a dam. Ice dams are most common on roofs with uneven attic temperatures, where escaping heat melts snow on the upper roof while the colder eave stays frozen.

A roof insurance deductible is the portion of a covered claim that the homeowner pays out of pocket before the insurance company pays the rest. If a covered roof claim is approved, the insurer pays the covered repair or replacement cost minus your deductible, and that deductible is always the homeowner's responsibility. Deductibles can be a flat dollar amount or a percentage of the home's insured value, and the specific amount is set in your policy.

An insurance supplement is an additional claim submitted after the initial adjuster estimate to request payment for damage, code-required work, or materials that were missed or underpriced in the original scope. It is a normal part of the claims process rather than a dispute, filed when a contractor's inspection or the tear-off itself reveals items the adjuster's estimate did not account for, such as hidden decking damage or an omitted code upgrade. A supplement request should be documented with photos and a clear explanation tied to the specific missed item.

Kick-out flashing is a small, angled piece of metal installed at the bottom of a step-flashing run, where a roof-to-wall joint ends at a gutter or roof edge. It diverts, or kicks out, the water running down that wall joint so it lands in the gutter instead of continuing behind the siding and down the wall. A missing kick-out flashing is a well-documented cause of hidden wall rot, since water can run behind siding for years before any damage is visible.

A mansard roof is a four-sided roof style with two distinct slopes on each side, a steep, nearly vertical lower slope and a much flatter upper slope, often used to create a full extra story of usable space beneath it. It is closely associated with French Second Empire and some Victorian architecture. Its steep lower slope is typically covered in shingles, slate, or metal, while the flat upper section behaves more like a low-slope roof and needs its own waterproofing approach.

A manufacturer's warranty is the shingle or roofing material maker's written guarantee against defects in the product itself, separate from any warranty on the quality of the installation. Standard material warranties commonly run 25 to 50 years, though coverage is often prorated after an initial full-coverage period, paying a declining percentage of replacement cost as the roof ages. Some manufacturers offer an enhanced, longer warranty when the roof is installed by a contractor certified at a specific tier with that manufacturer, extending coverage beyond the standard terms.

Modified bitumen is a low-slope roofing membrane made of asphalt reinforced with rubber or plastic polymers and laminated between layers of reinforcing fabric, then installed in rolled sheets across a flat or low-slope roof. The polymer modification makes it more flexible and better able to handle temperature swings than older built-up asphalt roofing without cracking. It can be installed with heat-welded seams, self-adhesive backing, or hot asphalt, and it is a common, cost-effective choice for additions, porches, and other low-slope sections of an otherwise shingled home.

A nail pop is a roofing nail that has backed partway out of the decking, pushing up the shingle above it into a small visible bump. It usually happens from improper nailing, wood shrinkage, or the deck flexing with temperature changes, and it leaves a raised nail head that can wear through the shingle above it or work its way further out over time. Nail pops are common and usually an easy, inexpensive repair, especially when caught before the exposed nail head causes a leak.

Net free area, often abbreviated NFA, is the actual open, unobstructed area of a vent through which air can pass, measured in square inches, as opposed to the vent's overall physical size. A louvered or screened vent's louvers and mesh block off part of its total opening, so its net free area is always smaller than its outer dimensions suggest. Building codes and ventilation calculations are based on net free area specifically, which is why two vents of the same visible size can provide very different amounts of actual airflow.

A pipe boot is the flashing that seals around a pipe where it passes through the roof, such as a plumbing vent. It is usually a metal flange with a rubber collar that fits snugly around the pipe to keep water out. Pipe boots are a very common source of roof leaks, because the rubber collar dries out, cracks, and fails years before the surrounding shingles do. A cracked pipe boot is one of the most frequent and easily fixed leak causes.

Ponding water is water that remains standing on a flat or low-slope roof for an extended period, typically defined in the industry as 48 hours or more after rainfall, rather than draining away. It usually points to a drainage design issue, an area of the roof that has settled or lost its slope, or a clogged drain, and it accelerates wear on the roofing membrane far faster than water that drains promptly. Correcting ponding generally involves improving slope with tapered insulation, adding or clearing drains, or a combination of both.

A power attic vent, sometimes called an attic fan, is a mechanical, electrically powered fan mounted on the roof or gable that actively pulls hot air out of the attic rather than relying on passive airflow. It typically runs on a thermostat, switching on once the attic reaches a set temperature. A power vent can move more air than passive ventilation alone, but without enough matched intake, it can pull conditioned air up from the living space instead of fresh air from outside.

A rafter is one of the sloped structural beams that runs from a roof's ridge down to its exterior wall, forming the angled framework the roof deck is nailed to. Rafters are cut and set individually on site, spaced at regular intervals, and sized according to the roof's span and pitch. They carry the weight of the decking, underlayment, and shingles above, transferring that load into the walls, so their condition and spacing directly affect how much weight a roof can safely carry.

The rake edge is the sloped edge of a roof that runs along a gable end, from the eave up to the ridge, as opposed to the eave, which runs along the horizontal side of the house. Like the eave, the rake edge is finished with drip edge to guide water off cleanly and give the shingles a straight line to overhang. Because wind hits the rake edge at an angle, shingles and drip edge there are especially important for keeping the roof's perimeter sealed against wind-driven rain.

Re-decking is the replacement of some or all of a roof's wood decking, discovered and done during a tear-off once the old shingles and underlayment are stripped away. Rotted, soft, or delaminated boards are cut out and replaced with new plywood or OSB before new underlayment and shingles go on, since nailing a roof to compromised wood undermines the whole installation. Because the extent of decking damage cannot be known until tear-off, re-decking is usually priced per sheet after the old roof is off, not as a fixed number in the original estimate.

Recoverable depreciation is the portion of an insurance payout that is held back on a Replacement Cost Value policy until the roof work is actually completed and documented. The insurer usually issues an initial check for the depreciated, Actual Cash Value amount first, then releases the remaining recoverable depreciation once the homeowner submits a final invoice and proof the work was finished. Collecting it generally requires completing the repair or replacement and providing that documentation within whatever timeframe the policy specifies.

Replacement Cost Value, or RCV, is the more generous of the two ways an insurance policy can value a roof claim. It pays the full cost to replace the damaged roof with a new one of similar kind and quality, without subtracting for age or wear. Many RCV policies pay in two parts: an initial amount up front, then the withheld depreciation once the work is completed and documented. Whether you have RCV or Actual Cash Value coverage is defined in your specific policy.

Ridge cap shingles are specially shaped shingles bent and installed along the peak, or ridge, of a roof to cover the joint where two slopes meet. They seal the exposed seam at the very top of the roof and, on roofs with a ridge vent, cover the vent opening while still allowing air to pass through. Ridge caps take more direct sun and wind stress than field shingles, so they are often the first shingles to show wear on an aging roof.

A ridge vent is a vent that runs along the peak, or ridge, of a roof and lets hot, humid air escape from the attic. Paired with intake vents low on the roof, it creates a steady flow of air that keeps the attic cooler and drier. Proper ridge ventilation protects the roof from heat and moisture damage, helps shingles last their full life, and can lower cooling costs during hot summers.

Roof decking, also called sheathing, is the layer of wood that forms the solid base of the roof. It is usually plywood or OSB nailed across the rafters, and everything else, the underlayment and shingles, attaches to it. The decking gives the roof its strength and a flat, sound surface to fasten to. Because it is hidden until the old roof is torn off, decking damage is the most common reason a final replacement price comes in above the estimate.

Roof maintenance is the ongoing, scheduled care of a roof, distinct from a one-time repair or replacement, aimed at catching small problems early and extending the roof's useful life. It typically includes a periodic inspection, clearing debris from valleys and gutters, checking flashing and pipe boots for early wear, and fixing minor issues like a small nail pop before they become active leaks. Roofs that receive regular maintenance tend to reach or exceed their expected service life, while neglected roofs often fail years earlier.

Roof moss is a low-growing plant that colonizes damp, shaded roof surfaces, most often on the north-facing slope or under heavy tree cover, where shingles stay wet longer between rain events. Beyond its appearance, moss holds moisture directly against the shingle surface and can work under shingle edges, which accelerates granule loss and can lift shingles enough to let water underneath. Moss is generally removed with a gentle, non-pressure method rather than power-washed, since aggressive cleaning strips granules and shortens the shingles' own life.

A roof overlay is when a new layer of shingles is installed directly over the existing old roof, without tearing the old shingles off first. It is faster and cheaper than a full tear-off because it skips the removal and disposal work. The tradeoff is real: an overlay hides any rot or damage in the decking, adds weight to the roof, traps heat, and usually does not last as long. Most building codes also limit a roof to no more than two layers.

Roof pitch is the measure of how steep a roof is. It is written as a ratio of vertical rise to horizontal run, such as 6:12, meaning the roof rises 6 inches for every 12 inches it runs horizontally. A higher first number means a steeper roof. Pitch affects how a roof sheds water, what materials can be used, and how much a replacement costs, because steeper roofs are slower and more dangerous to work on.

A roof plane is one continuous, flat sloped surface of a roof, bounded by ridges, hips, valleys, or edges where it meets another plane. A simple gable roof has just two planes, while a roof with multiple dormers, hips, and additions can have a dozen or more. Each additional plane adds seams that need flashing and increases the labor needed to measure, cut, and shingle the roof correctly, which is one of the main reasons roof complexity, not just size, drives replacement cost.

Roof sagging is a visible dip, sway, or unevenness in the roofline where it should be straight, usually a sign of a structural problem with the rafters, trusses, or decking rather than a shingle issue. Common causes include water-weakened or rotted framing, rafters undersized for the roof's span, or years of added weight from multiple layers of shingles. Because a sagging roof points to a structural, not cosmetic, problem, it needs to be assessed before any re-roofing or repair work moves forward.

A roof tear-off is the complete removal of the old roofing materials down to the bare wood decking before a new roof is installed. Stripping everything off lets the crew inspect and repair the decking, install fresh underlayment, and start the new roof on a sound base. A full tear-off is the proper way to replace a roof, even though it costs more in labor and disposal than simply layering new shingles over the old ones.

A roof truss is a prefabricated, triangulated wood frame built off-site in a factory and set into place as one complete unit to support the roof deck. Unlike rafters, which are cut and assembled piece by piece on the job, trusses use an internal web of smaller members engineered together for strength, which lets them span farther without a load-bearing wall underneath. Trusses are now the more common framing method on new construction because they are faster to install and more consistent in their engineering.

A roof valley is the V-shaped channel formed where two sloped sections of roof meet and run downward together. Valleys collect and carry a large volume of rainwater off the roof, which makes them one of the busiest and most leak-prone areas. Because so much water funnels through them, valleys are flashed and built with extra care, and a failed valley is a common source of leaks on an older or poorly installed roof.

A roof warranty is a manufacturer's or contractor's written promise to stand behind the materials or the installation of a roof for a set period of time. There are two distinct kinds: a materials warranty from the shingle manufacturer, which commonly runs 25 to 50 years but usually covers only defective product, and a workmanship warranty from the installing contractor, which covers installation errors and is often much shorter. Reading which kind of warranty covers a specific problem is essential, since the two are not interchangeable.

A roofing square is the unit roofers use to measure and price a roof. One square equals 100 square feet of roof surface, or a 10 foot by 10 foot area. Material and labor are figured by the square, not by the home's floor space, so a roof is quoted in squares rather than total square feet. A typical single-family home has a roof somewhere in the range of 15 to 30 squares.

A shed roof is a single flat plane sloping in one direction, with no ridge, hip, or valley, resembling one half of a simple gable roof. It is common on additions, porches, and garages because it is simple to frame and quick to shingle, and its single slope drains cleanly to one edge as long as that slope is steep enough to move water. A shed roof built at too low a pitch behaves more like a flat roof and needs low-slope materials instead of standard shingles.

Shingle blistering is small, raised bubbles that form on the surface of an asphalt shingle, usually caused by trapped moisture or gas expanding under the shingle's surface in the heat. When a blister eventually pops or wears through, it takes the protective granules with it and exposes bare asphalt underneath, creating a weak spot that ages faster than the rest of the shingle. Blistering is more a sign of manufacturing or ventilation issues than storm damage, and it tends to show up scattered across a roof rather than in one impact zone.

Shingle curling is when the edges or corners of an asphalt shingle lift and bend away from the roof surface instead of lying flat, usually as the shingle ages and its asphalt dries out and loses flexibility. It shows up as either cupping, where the edges turn upward into a concave, bowl-like shape, or clawing, where the center rises while the edges curl downward or stay flat. Curling is a strong sign a roof is nearing the end of its service life and more vulnerable to wind and water intrusion.

Shingle exposure is the portion of each shingle course left visible to the weather after the next course above it overlaps it, typically around 5 to 5 5/8 inches on a standard architectural shingle. It is set by the manufacturer's specifications and directly controls how many layers of shingle protect the roof at any given point, since a smaller exposure means more overlap and more layers of material. Installing shingles at the wrong exposure, whether too much or too little, is an installation error that shortens the roof's expected life even when the shingle product itself is high quality.

Granules are the tiny mineral pebbles bonded to the surface of an asphalt shingle. They give the shingle its color and, more importantly, shield the asphalt underneath from the sun's ultraviolet rays. As long as the granules stay put, the shingle is protected. When they wear off or get knocked loose by hail or age, the bare asphalt is exposed, dries out, and the shingle starts to fail. Granule loss is one of the clearest signs a roof is aging or storm-damaged.

A slate roof is a roofing system made of thin, individual tiles split from natural stone, most often installed one at a time with each tile overlapping the course below it. It is among the longest-lasting roofing materials available, with a service life commonly measured in generations rather than decades, but it is also among the heaviest, often requiring reinforced framing to support its weight. Slate is not repaired with standard shingle techniques; broken tiles are replaced individually by someone trained in slate-specific methods.

The soffit is the underside of the roof overhang, the surface you see when you stand under the edge of the roof and look up. Besides finishing off the overhang, the soffit usually houses the intake vents that pull fresh air into the attic. A healthy, vented soffit is a key part of attic ventilation, and a damaged or rotted soffit is often the first visible sign of a water or pest problem at the roof's edge.

A soffit vent is an intake vent built into the underside of the roof overhang, letting outside air flow up into the attic. Paired with an exhaust vent higher on the roof, such as a ridge vent, soffit vents are the intake half of a balanced attic ventilation system. They come as small round or rectangular vents cut into individual soffit panels, or as a continuous perforated strip running the full length of the soffit, and either style is only useful if the airflow above it is not blocked.

Standing seam metal roofing is a metal roof system made of vertical panels joined by raised interlocking seams, with no exposed fasteners visible on the finished surface. The seams sit above the water line and the panels are anchored using concealed clips underneath, which lets the metal expand and contract with temperature changes without stressing the fasteners. It is the premium tier of metal roofing, valued for its clean lines and long service life, and it typically costs more than exposed-fastener metal panels of similar gauge and coating.

Starter strip shingles are a special first row of shingles installed along the edges of a roof, underneath the visible first course. They have a strip of adhesive positioned to seal down the bottom edge of the shingles above them and they leave no gaps where the shingle seams fall. This locks the roof's edge against wind uplift and blocks water from getting under the first row, which is why proper starter is essential at the eaves and rakes.

A static roof vent, also called a box vent, is a simple, fixed exhaust vent installed on the roof with no moving parts, letting hot attic air rise up and out through louvers or a screened opening. It works passively, using the natural tendency of hot air to rise, and is typically installed in multiples spaced across a roof to move enough total air. Static vents are an older, still-common alternative to a continuous ridge vent, which generally moves air more evenly across the whole attic.

Step flashing is a series of small, L-shaped metal pieces installed one at a time, woven in with each course of shingles, where a roof slope meets a vertical wall. Each piece overlaps the one below it and is tucked partly under the siding above, so water is stepped down the wall and onto the roof surface instead of behind the siding. It is the standard flashing method anywhere a roof runs into a wall, such as against a dormer, a chimney side, or an addition.

A storm chaser is an out-of-town roofing crew that follows severe weather from region to region, soliciting fast repair or replacement jobs in the days immediately after a hailstorm or windstorm and then moving on before any problems with the work surface. The term describes a business pattern, not a specific company, and common indicators include out-of-state vehicles, no verifiable local address or license, high-pressure same-day contracts, and unusually large up-front payment demands. Not every unfamiliar crew canvassing after a storm fits the pattern, but the pattern itself is well documented across the industry.

Sub-fascia is the structural framing board, usually a piece of dimensional lumber, that runs behind the visible fascia trim and caps the ends of the rafters or trusses. It is the load-bearing piece; the fascia board homeowners see is a decorative and functional cover nailed over it. Sub-fascia gives the roof edge its shape and gives the fascia and gutters something solid to attach to. Because it sits hidden behind the trim, damage to it usually surfaces only once the fascia or roofing is opened up for repair.

Synthetic underlayment is a woven or non-woven polymer sheet installed under shingles as the roof's secondary water barrier, replacing traditional asphalt-saturated felt paper. It is lighter, stronger, and more tear- and UV-resistant than felt, which lets it stay exposed longer during construction and hold up better to foot traffic before the shingles go on. Most manufacturers and roofing crews now use synthetic underlayment as the default choice on new installations because of its durability and consistent performance compared with felt.

Thermal splitting is cracking that develops in a roofing membrane, most often single-ply or built-up low-slope materials, caused by the repeated expansion and contraction of the material as temperatures rise and fall. Over years of cycling between hot sun and cool nights, a membrane loses the flexibility to move without stress, and splits typically appear where the membrane is fastened, seamed, or otherwise restricted from moving freely. A split is a direct break in the waterproofing layer, so it is treated as an active leak risk, not a cosmetic issue.

Three-tab shingles are a flat, single-layer asphalt shingle cut with two slots so each strip appears to be three separate rectangular tabs once installed. They are lighter and less expensive than architectural shingles but generally carry a shorter warranty and hold up less well to wind and impact. Once the standard roofing product, three-tab shingles have been largely replaced by architectural shingles on new construction and most replacements, though they still appear on some existing roofs and budget projects.

TPO, short for thermoplastic polyolefin, is a single-ply membrane roofing material used on flat and low-slope roofs, installed in large sheets that are heat-welded together at the seams to form one continuous waterproof surface. It is typically white or light-colored, which reflects sunlight and helps reduce heat buildup compared with darker roofing materials. TPO is one of the most widely used low-slope roofing systems today because it balances a relatively low material cost with strong seam strength and solid puncture resistance.

A turbine vent is a round, wind-driven attic exhaust vent with fins that spin when the wind blows, using that spin to pull hot air up and out of the attic faster than a passive vent alone. It sits on the roof like a static vent but adds mechanical assistance on windy days, and works more like a plain vent when the air is still. Turbine vents are an older, still-common ventilation option, though many newer roofs favor a continuous ridge vent, which has no moving parts to maintain.

Underlayment is the protective layer installed directly on the roof decking, underneath the shingles. It acts as a second line of defense against water, so if wind drives rain under the shingles or a shingle is lost in a storm, the underlayment keeps the deck and the home below it dry. Modern roofs use either a felt paper underlayment or a tougher synthetic underlayment, with synthetic now the common choice for its strength and water resistance.

Wind uplift is the force created when wind blows across a roof and generates lower air pressure above the surface than below it, effectively pulling shingles and roofing components upward rather than simply pushing them sideways. It concentrates hardest at roof edges, corners, and ridges, which is why those areas need extra fastening, starter strip, and properly sealed shingles to resist it. Wind uplift damage often shows as shingles that are lifted, creased, or missing along an edge, even when the rest of the roof looks undisturbed.

A workmanship warranty is a contractor's written promise to fix problems caused by errors in how a roof was installed, separate from the manufacturer's warranty on the materials themselves. It typically covers issues like improperly sealed flashing or incorrect nailing that lead to a leak, offered at the discretion of the installing contractor, with its own length and terms set by that company rather than any industry standard. Workmanship warranties tend to run shorter than material warranties, and their value depends on the contractor still being in business.

Xactimate is estimating software widely used across the insurance and construction industries to calculate the cost of repairing or replacing storm-damaged property, including roofs. Insurance adjusters and many contractors use it to generate a line-item estimate based on standardized regional pricing data for materials and labor, which becomes the basis for a claim's payout. A roof estimate built in Xactimate is a structured, itemized document, and understanding its line items can help a homeowner see exactly what a claim was priced to cover.