• AlligatoringA pattern of shrinkage cracks resembling alligator skin on aged asphalt, coal-tar or coated roof surfaces exposed to sun and heat.
• Animal and Bird Damage to RoofsDamage by squirrels, raccoons, rats, birds, possums and insects that chew, tear or nest in roofs, vents, soffits and attics.
• Attic MouldMould growth on attic sheathing and framing, almost always driven by moisture from indoor air leaks, exhaust ducts or roof leaks.
• Copper Run-Off and StainingRainwater flowing off copper carries dissolved copper that can stain masonry green and corrode aluminium, zinc and zinc-coated steel downstream.
• Creep in Lead and Zinc RoofingCreep is the slow, permanent stretching of soft metals such as lead and zinc under their own weight and repeated thermal movement, causing thinning and tears.
• Emergency Roof TarpingCovering a damaged roof temporarily with a tarp or plastic sheeting to keep water out until permanent repairs can be made.
• Fastener Back-OutGradual loosening of screws or nails so their heads rise above the roof surface, breaking the seal and creating leak points.
• Flashing FailureBreakdown of the metal or membrane pieces that seal a roof at walls, chimneys, valleys and penetrations; a leading cause of roof leaks.
• Galvanic Corrosion and Metal CompatibilityGalvanic corrosion is accelerated attack on one metal when it touches, or is wetted by run-off from, a more noble metal; it governs which roof metals can be combined.
• Granule LossThe shedding of the mineral granules that coat asphalt shingles; normal in small amounts, a warning sign when heavy, patchy or premature.
• Gutter ProblemsCommon faults in roof gutters and downpipes, including clogging, overflow, incorrect pitch, ice build-up, leaking joints and sagging.
• Hail Resistance of Metal RoofsMetal roofs are hard to puncture by hail; many assemblies reach UL 2218 Class 4, though large hailstones can still leave cosmetic dents.
• Korean Asbestos Slate RoofsAsbestos-cement slate roofs spread across rural South Korea from the 1970s; since 2011 local governments subsidise their removal and replacement.
• Leaky Homes CrisisNew Zealand’s weathertightness failure affecting timber-framed buildings built 1988-2004, estimated in 2009 to cost about NZ$11.3 billion.
• Lichen on RoofsCrusty, slow-growing patches formed by a fungus and alga partnership that cling tightly to roofs and are hard to remove without damage.
• Membrane ShrinkagePermanent loss of size in some single-ply roof membranes, which can pull on flashings, tear seams and lift edges.
• Metal Roof Noise: Myth and FactMetal roofs over a solid deck and insulation are generally no louder in rain than other roofs; noise is mainly an issue with sheets over open framing.
• Metal Roofs and Lightning: Myth and FactMetal roofs do not attract lightning; strike risk depends on height, terrain and storm frequency, and metal's noncombustibility can reduce fire risk.
• Nail PopsRoofing or deck nails that work upward and lift or puncture the shingle above, creating a bump and a possible leak point.
• Nail SicknessFailure of the nails holding slates or tiles, usually through corrosion, so units slip or fall even though the slates themselves are sound.
• Oil CanningOil canning is visible waviness in the flat areas of metal panels caused by locked-in stress or restrained movement; it is generally cosmetic.
• Red Rust on Metal RoofsIron oxide corrosion on steel roofing that appears once the protective zinc or zinc-aluminium coating has been used up or damaged.
• Ridge Repointing and RebeddingRenewal of the mortar that beds and seals ridge and hip tiles; in the UK, current standards also require mechanical fixing of these tiles.
• Roof Age EstimationMethods for working out how old a roof is, using records, permits, product markings and physical condition.
• Roof Algae (Black Streaks)Dark streaks on roofs, especially asphalt shingles, caused by airborne cyanobacteria commonly identified as Gloeocapsa magma.
• Roof BlisteringRaised bubbles in asphalt shingles or low-slope membranes caused by trapped gas, moisture or volatiles expanding under heat.
• Roof Cleaning MethodsWays of removing algae, moss, lichen and dirt from roofs, chiefly low-pressure soft washing, manual removal and pressure washing.
• Roof Inspection After StormsHow to check a roof safely after wind, hail or heavy rain, document damage, and arrange temporary protection and professional assessment.
• Roof Insurance ClaimsA neutral overview of how property insurance claims for roof damage generally work, including coverage types, depreciation and documentation.
• Roof Leak DetectionThe process of tracing where water actually enters a roof, which is often some distance from where it appears inside the building.
• Roof Maintenance Checklist by SeasonA season-by-season list of routine roof checks and upkeep tasks for homes and low-slope buildings, plus inspections after major storms.
• Roof MossMoss growth on shaded, damp roofs that holds water, lifts shingles and tiles, and blocks drainage if left to build up.
• Roof Repair vs ReplacementThe factors owners and roofers weigh when deciding whether to fix part of a roof or replace the whole covering.
• Roof Rot (Fascia, Soffit and Deck)Fungal decay of roof timbers such as fascia boards, soffits, sheathing and rafter ends, caused by long-term wetting.
• Sagging Roof DeckA visible dip or wave in a roof plane caused by deflecting sheathing, rafters, trusses or ridge, from overload, decay or inadequate framing.
• Seam FailureOpening or separation of the joints between sheets of a roof membrane or metal panel, allowing water into the roof assembly.
• Shingle Curling, Clawing and CuppingDistortion of asphalt shingles in which edges turn up (cupping) or corners and middles lift (clawing), usually from age, heat or moisture.
• Slate DelaminationThe splitting and flaking of roofing slate into thin layers as it weathers, marking the end of an individual slate's service life.
• Slipped and Cracked Roof TilesDisplacement or breakage of clay or concrete roof tiles from failed fixings, impact, foot traffic, frost or movement.
• Thatch Maintenance and DecayThe care cycle of a thatched roof, including periodic ridge replacement, patching, and eventual rethatching as the coatwork wears away.
• White Rust (Wet Storage Stain)A white, powdery zinc corrosion product that forms on galvanised steel kept wet without air, often while panels are bundled in storage.
• Wind DamageRoof damage caused by wind uplift, typically lifted, creased, torn or missing shingles, tiles or panels, often starting at edges.
• Zinc and Copper StripsMetal strips fixed near a roof's ridge whose rain runoff carries metal ions that discourage moss, algae and lichen below.