Roofing terms, in plain English

The structural layer the whole roof system is fastened to — usually plywood or OSB panels nailed over the rafters or trusses, sometimes wood planks on older homes or concrete on some buildings. Everything above it depends on it holding fasteners.

In South Florida: Rotted or delaminated sections are usually found during tear-off; replacing them is part of a re-roof, and the nailing of new sheathing is inspected.

• Not the same as Underlayment: Underlayment is the waterproofing sheet installed on top of the deck, not the deck itself.

Read more: A re-roof, day by day

The framing members that carry the roof. Rafters are individual sloped boards; trusses are factory-built triangulated frames. Their size, spacing and connection to the walls decide how much weight the roof can carry and how well it resists uplift.

Read more: Tile weight and structure

How the roof framing is tied down to the walls — from toe-nails alone to metal clips, single wraps or double wraps. In high winds the roof is pulled upward; this connection is what keeps it on the house.

In South Florida: It is one of the attributes recorded on the Florida wind-mitigation form, which is why it can affect a windstorm premium.

Read more: Roofing on CBS homes · How a roof resists wind

A reinforced concrete beam cast along the top of a concrete-block wall. Roof straps are embedded in or anchored to it, so it is the link between the masonry walls and the roof framing.

Read more: Roofing on CBS homes

How steep a roof is, written as inches of rise per 12 inches of run — a 4:12 roof rises 4 inches every foot. Pitch decides which materials are allowed and changes how much roof surface sits over the same footprint.

• Not the same as Low-slope roof: “Low-slope” is a range of pitch, not a material.

Read more: Pitch and roof area in the cost calculator

The unit roofers price and order material in: 100 square feet of roof surface. A 2,500 sq ft roof is 25 squares. It measures the sloped surface, not the floor area of the house.

Read more: Estimate your roof in squares

The eave is the lower, horizontal edge of a sloped roof (where gutters go); the rake is the sloped edge at a gable end; the overhang is how far either projects past the wall. Edges see the highest wind suction on a roof, so their fastening and edge metal matter.

The fascia is the vertical board along the roof edge that gutters and edge metal attach to; the soffit is the underside of the overhang, often vented. Rotted fascia is commonly repaired during a re-roof.

The ridge is the top horizontal line where two slopes meet; a hip is a sloped external corner where slopes meet; a valley is the internal corner where two slopes drain toward each other. Valleys carry the most water on a roof and are a frequent leak point.

Read more: Five common leak points

A low wall that extends above the roof line, common on flat-roofed homes and commercial buildings. The joint between the roof membrane and the parapet, and the cap on top, are classic leak paths.

Read more: Five common leak points

The waterproofing layer installed directly on the deck beneath tile, metal or shingle. On a tile roof it does most of the waterproofing — the tile mainly sheds bulk water and protects the underlayment from sun — so an aged underlayment can leak even when the tile looks fine.

In South Florida: In the HVHZ the underlayment must be part of the approved roof system for the product being installed.

• Not the same as Decking: The deck is the structural layer underneath it.
• Not the same as Secondary water barrier: A secondary water barrier is a specific, sealed approach to the underlayment layer.

Read more: Why tile roofs leak · Tile roofing guide

A rubberized-asphalt (or similar) membrane with an adhesive back that bonds directly to the deck and seals around nails. It is widely used as the waterproofing layer under tile and metal and as a secondary water barrier.

• Not the same as Felt (organic or fiberglass base sheet): Felt is mechanically fastened and does not self-seal around fasteners.

Asphalt-saturated sheet underlayment fastened with nails and, where required, metal tin caps. Older roofs often have a felt base layer under a mopped or hot-applied cap sheet.

Read more: Tin cap

A layer that keeps water out of the house if the roof covering is blown off — for example self-adhered tape over all deck seams or a fully adhered underlayment. It is one of the features the Florida wind-mitigation form records.

Read more: Wind mitigation and your premium

A thin metal disc driven with a nail to hold felt underlayment down with a larger bearing area than a nail head alone. Used where the code or the approved system calls for it.

Metal (or membrane) pieces that waterproof the joints a roof covering can’t seal on its own — walls, chimneys, skylights, valleys, penetrations and edges. Most leaks on otherwise sound roofs start at flashing.

• Not the same as Counterflashing: Counterflashing is the piece on the wall that covers the top of the base flashing.

Read more: Five common leak points

The metal set into or onto a wall that overlaps the top of the base flashing, so water running down the wall is directed onto the roof rather than behind the flashing. Failed stucco or sealant at this joint is a common source of wall-line leaks.

An L-shaped metal strip along eaves and rakes that guides water off the roof edge into the gutter and away from the fascia, and protects the deck edge. It is also part of how the roof edge is secured against wind.

The flashing that seals around plumbing vent pipes where they pass through the roof. Rubber collars crack in UV and lead jacks can be damaged, which makes boots a frequent small leak.

Read more: Five common leak points

A small built-up ridge that diverts water around an obstacle — behind a chimney or between drains on a flat roof — so it doesn’t pond against it.

Read more: Ponding on flat roofs

Barrel (S-profile) tile is the curved profile common on Mediterranean-style homes; flat tile is a low-profile alternative. Both come in concrete or clay and are installed over an underlayment as part of an approved system.

• Not the same as Clay vs concrete tile: Profile (barrel vs flat) and material (clay vs concrete) are separate choices.

Read more: Tile roofing guide

Clay tile is fired clay — color goes through the body and it resists fading; concrete tile is cement-based, generally less expensive and often heavier per square. Both can last decades; the underlayment beneath them usually decides when the roof needs work.

Read more: Tile roofing guide

Ways of attaching tile: with an approved polyurethane foam adhesive, with nails or screws (sometimes plus clips), or — on older roofs — with mortar. The permitted method and its pattern come from the product approval of the specific tile system, not from the installer’s preference.

Read more: Tile roofing guide

Removing existing tiles, replacing the underlayment (and any damaged deck) and re-installing the same tiles. It can work when the tile is sound and enough matching tile exists; it is still roofing work that falls under the code and permit rules for the jurisdiction.

• Not the same as Re-roof: A re-roof replaces the roof covering itself, not only the layers beneath it.

Read more: Lift-and-relay vs replacement

How far each course of tile or shingle overlaps the course below. The overlap is what keeps wind-driven rain from getting under the covering; it is set by the manufacturer’s instructions.

A metal roof system of long vertical panels joined by raised seams, with the fasteners hidden under the seams (attached with clips or a nail flange). Fewer exposed fasteners means fewer places for water and corrosion to start.

• Not the same as 5V-crimp: 5V-crimp is fastened through the panel face, so the fasteners are exposed.

Read more: Metal roofing guide

A metal panel profile with five V-shaped ribs, fastened with screws through the face of the panel. Common on Florida homes; the exposed fasteners and their washers need periodic attention.

• Not the same as Standing seam: Standing seam hides its fasteners under the seam.

Read more: Metal roofing guide

Polyvinylidene fluoride — a resin used in high-performance metal roof finishes because it holds color and resists chalking under strong sun. Kynar 500® and Hylar 5000® are brand names of PVDF resins; the finish itself is made by the coil coater and warranted by the panel manufacturer.

Read more: Metal roofing guide

Corrosion that happens when two different metals touch in the presence of moisture — for example the wrong fasteners or flashing against aluminum panels. Salt air speeds it up, which is why fastener and accessory compatibility matters near the coast.

Read more: Metal roofing guide

An asphalt shingle made of laminated layers, thicker and more textured than a flat three-tab shingle. In the HVHZ it must be installed per its product approval, including the specified underlayment and fastening.

Read more: Shingle roofs in the HVHZ

A roof with very little pitch — what most people call a “flat” roof, though it should still slope enough to drain. It uses continuous membranes rather than overlapping tile or shingles.

Read more: TPO vs modified bitumen vs EPDM · Flat roofing in South Florida

Thermoplastic polyolefin — a single-ply, usually white membrane whose seams are joined with hot air into a continuous sheet. Common on commercial and residential low-slope roofs.

• Not the same as EPDM: EPDM is a rubber membrane whose seams are joined with tape or adhesive, not heat-welded.

Read more: TPO vs modified bitumen vs EPDM

Ethylene propylene diene monomer — a synthetic rubber single-ply membrane, traditionally black, with seams joined by tape or adhesive. Flexible and long-used on low-slope roofs.

• Not the same as TPO: TPO seams are heat-welded.

Read more: TPO vs modified bitumen vs EPDM

Asphalt modified with polymers (SBS or APP) and reinforced, installed in multiple plies — typically a base sheet and a granule-surfaced cap sheet — by torch, hot asphalt, cold adhesive or self-adhesion.

Read more: TPO vs modified bitumen vs EPDM

Water that stays on a low-slope roof long after rain instead of draining. It points to inadequate slope, deflection or blocked drains and speeds up membrane wear.

Read more: Ponding water on flat roofs

Rigid insulation boards cut with a built-in slope, used under a low-slope membrane to create or improve drainage toward drains or scuppers.

Read more: Ponding water on flat roofs

An opening through a parapet or roof edge that lets water drain off a low-slope roof, often into a collector box and downspout. Clogged scuppers are a common cause of ponding.

The metal cap that covers the top of a parapet wall and sheds water away from it. Loose or poorly sealed coping lets water into the wall and behind the roof membrane.

The part of Florida — Miami-Dade and Broward counties — where the Florida Building Code applies its strictest wind provisions: products need an approval valid for the HVHZ, and roofs follow HVHZ-specific installation standards and inspections.

In South Florida: Palm Beach County is outside the HVHZ but still in a high-wind region of the code.

Read more: Miami-Dade roofing: code and approvals · Which Florida Building Code applies

A product approval issued by Miami-Dade County after testing a product (a tile system, a window, a shingle) against HVHZ requirements. It states exactly how the product must be installed and the pressures it is approved for.

• Not the same as Florida Product Approval (FPA / FL#): Florida Product Approval is the statewide system; not every FPA is valid in the HVHZ.

Read more: Miami-Dade roofing: code and approvals · NOA for impact windows

The State of Florida’s product approval system, administered through the Florida Building Commission. Each approval has an FL number and lists where and how the product may be used, including whether it is approved for the HVHZ.

• Not the same as NOA (Notice of Acceptance): An NOA is Miami-Dade County’s approval.

Read more: NOA and product approval for windows

The upward pull wind creates on a roof as it flows over it — a suction, not a push. Corners and edges see the strongest uplift, which is why fastening is denser there.

• Not the same as Uplift pressure (design pressure): Uplift is the effect; uplift pressure is how it is measured and designed for.

Read more: How wind takes a roof off

The calculated suction a roof area must resist, in pounds per square foot (psf), based on the building’s location, height, exposure and roof zone. A product approval states the pressures a system resisted in testing; the installed system must meet or exceed what the design calls for.

Read more: Design pressure on impact windows

The statewide building code, updated in editions on a regular cycle. The edition that applies to a job is generally tied to when the permit application is submitted, so two roofs done months apart can fall under different editions.

Read more: Which edition applies to your roof

An inspection that records a home’s wind-resistant features — roof covering, deck attachment, roof-to-wall connection, roof shape, secondary water barrier, opening protection — on the state form OIR-B1-1802 so an insurer can apply mitigation credits.

• Not the same as 4-point inspection: A 4-point inspection looks at condition and age of four systems, not wind features.

Read more: Wind mitigation and your premium · 4-point vs wind mitigation

An insurance inspection of four systems — roof, electrical, plumbing and HVAC — usually requested for older homes to show their condition and age. The insurer decides when it is required and what it accepts.

• Not the same as Wind mitigation inspection: A wind mitigation inspection documents wind-resistant features for premium credits.

Read more: 4-point vs wind mitigation

A visual assessment of the roof covering, flashing, penetrations, drainage and signs of water entry, with a written report. Its scope and limits depend on access and on what the inspection is for (repair planning, a sale, insurance).

Read more: Roof inspection guide

A separate, usually higher deductible that applies only to losses from a hurricane as the policy and Florida law define it. Damage from an ordinary thunderstorm falls under the policy’s other deductible.

Read more: Afternoon storm vs hurricane damage

A structural inspection Florida law requires for certain condominium and cooperative buildings at set ages, performed by a licensed engineer or architect. It is separate from the reserve study, though both affect roofing decisions for associations.

Read more: Condo roofs, milestone inspections and SIRS

A study Florida law requires certain condominium associations to perform, listing the remaining life and replacement cost of key building components — the roof among them — so reserves are funded for them.

Read more: Condo roofs, milestone inspections and SIRS

Replacing the roof covering — normally tearing off the old system to the deck, repairing the deck and installing a new underlayment and covering. It requires a permit and inspections.

• Not the same as Lift-and-relay: Lift-and-relay re-uses the existing tile.
• Not the same as Roof repair: A repair fixes a limited area of the existing roof.

Read more: Roof replacement · A re-roof, day by day

Fixing a limited area of an existing roof — a flashing, a valley, damaged tiles. Whether a repair can be done, and whether it needs a permit, depends on its extent and the local building department.

• Not the same as Re-roof: A re-roof replaces the whole covering.

Read more: Roof repair · Repair or replace?

Removing the existing roofing down to the deck before re-roofing. Each additional old layer adds labor and disposal, and exposes the deck for inspection and repair.

Read more: Tear-off layers in the cost calculator

The stage of a re-roof when the underlayment is installed and the house is protected from rain even though the final covering is not on yet. In many jurisdictions it is inspected before work continues.

Read more: A re-roof, day by day

The building-department authorization for roofing work, issued by the city or, in unincorporated areas, the county. It lists the approved products and triggers the required inspections; it should be closed (finaled) when the work passes.

Read more: Roof permits, step by step

A recorded document, required under Florida’s construction-lien law for many improvement projects, that identifies the owner, contractor and property before work begins. Building departments commonly ask for it before inspections.

Read more: Roof permits, step by step

The roofing manufacturer’s promise about its products — and, on enhanced or system warranties, sometimes the installed system — subject to registration, approved installation and maintenance terms.

• Not the same as Workmanship warranty: Workmanship is warranted by the contractor, not the manufacturer.

Read more: Manufacturer vs workmanship warranty

The contractor’s written promise about the installation itself — leaks or failures caused by how the roof was put on. Its term and exclusions should be stated in the contract.

• Not the same as Manufacturer warranty: The manufacturer warrants its materials.

Read more: Manufacturer vs workmanship warranty

A roof surface that reflects more sunlight and releases absorbed heat efficiently, measured by solar reflectance and thermal emittance (combined as SRI). It lowers roof surface temperature; how much it saves depends on insulation, ducts and the building.

Read more: Cool roofs in Miami