Why the vocabulary matters
None of these terms are difficult once stated plainly. They are simply trade vocabulary, and the asymmetry between the person writing the proposal and the person paying for it is what makes comparison hard. Each entry below gives the definition and then the part that actually matters: what it changes about your roof.
Terms that appear in almost every estimate
Ice-and-water shield
A self-adhering waterproof membrane applied directly to the deck, usually at eaves, in valleys, and around penetrations, that seals around fasteners driven through it. In this climate it is what stops water backed up behind an ice dam from entering the building. How far it extends up from the eave, and whether it reaches past the interior wall line, is a genuine difference between two proposals.
Underlayment
The layer between the deck and the covering across the general field of the roof, either felt or a synthetic sheet. It is a secondary barrier, not a roof. It is also invisible once covered and therefore an easy place to reduce a bid price.
Decking or sheathing
The structural panel or plank surface fastened to the rafters, onto which everything else is built. Its condition cannot be known until the covering is removed, which is why a replacement contract needs an allowance quantity and a written unit price.
Decking allowance
A stated quantity of replacement sheathing included in the contract price, with a written unit price for anything beyond it. It is the most common change order on a roof replacement. Without one, the cost of bad decking is negotiated after it is found.
Step flashing
Individual pieces of metal woven into the roof covering course by course where a roof plane meets a vertical wall or chimney. Reused step flashing is one of the most common reasons a newly replaced roof leaks. Ask whether it is new metal.
Counter flashing
Metal let into or attached to masonry that covers the top edge of the step flashing beneath it. Without it, water enters at the top edge of the step flashing. Sealant instead of counter flashing is a repair with an expiry date.
Cricket
A small peaked structure built on the upslope side of a chimney to divert water and snow around it. Wider chimneys on a slope generally need one. Its absence lets debris and snow pile against the upslope face and is a recurring cause of leaks and rot.
Drip edge
Metal at the roof edge that directs water off the sheathing and into the gutter. Not behind it. Missing or incorrectly installed drip edge is one of the most common reasons a fascia rots on an otherwise sound roof.
Pipe boot
The flashing assembly sealing where a plumbing vent pipe passes through the roof, typically a flange with a rubber or synthetic collar. The collar is a wear item with a shorter life than the roof, and it is one of the most common single-point leaks on a mid-life roof.
Valley
The internal angle where two roof planes meet, carrying the combined water from both. Water concentrates in this angle. Valleys are a common leak location, and how they are built, woven, closed-cut, or open metal, is a specification worth asking about.
Ridge and ridge vent
The peak where two roof planes meet. A ridge vent is an exhaust opening running along it. A ridge vent is only the exhaust half of a ventilation system. Without open intake at the soffits it draws air from the heated house instead of from outside.
Soffit and soffit intake
The underside of the roof overhang, and the vents in it that let outside air into the attic. Blocked soffit intake, commonly by insulation added later, is the single most frequent ventilation fault, and it makes attic moisture and ice dams worse.
Baffle
A channel installed at the eave that keeps an air path open between the insulation and the roof deck. It is what stops insulation from blocking the soffit intake. Adding insulation without baffles is how a well-intentioned upgrade causes attic frost.
Fascia
The horizontal board at the roof edge, usually where the gutter is attached. Rot here is a symptom, not a cause. Water is reaching it repeatedly, and replacing the wood without fixing that repeats the repair.
Terms for metal, low-slope, and commercial work
Square
A roofing unit of area equal to 100 square feet of roof surface. Squares, not square feet. Roofs are priced by measured roof surface, not by the interior floor area of the building.
Pitch or slope
The steepness of a roof, usually expressed as inches of rise over 12 inches of run. Pitch changes how the work is performed, how long it takes, what safety equipment is needed, and which materials are suitable.
Low-slope roof
A roof too shallow to shed water the way a pitched roof does, typically covered with a membrane. Not shingles. Often called flat, but designed to drain. Water beneath a membrane can travel far from the entry point, which makes leak location genuinely harder.
Tear-off versus recover
Tear-off removes the existing covering down to the deck. A recover or layer-over installs new material over the old. A recover hides exactly what you need to see: deck condition. Weight goes up, too, and warranty coverage narrows.
Standing seam
A metal roof system whose panels are joined by raised seams that conceal the fasteners, with clips allowing the panel to move. Distinct from exposed-fastener metal, whose screws pass through the panel face with gaskets that age and need maintenance. They are not the same purchase.
Snow retention
Engineered components fitted to a roof to hold snow in place and control where and how it releases. A metal roof sheds decisively. Where that load lands, over an entrance, walkway, meter, or lower roof, is a safety question that has to be designed.
Cover board
A layer between the insulation and the membrane on a low-slope roof, improving impact resistance, fire performance and attachment. It is frequently the difference between two otherwise similar commercial proposals, and omitting it is an easy way to reduce a bid price.
Ponding
Water still standing on a low-slope roof well after rain has stopped, in the same places each time. Not automatically a failure, but it stresses seams and flashings, adds weight, and in freeze-thaw conditions works at the membrane.
Moisture survey
A defined investigation, commonly infrared, nuclear or capacitance, to identify suspected wet areas within a low-slope assembly. Whether the insulation is wet determines which options remain available, so this usually precedes any significant commercial roof decision.
Workmanship warranty
Coverage from the installing contractor for defects in how the roof was installed, distinct from the manufacturer's material or system coverage. Three different things, three different papers. Manufacturer material, manufacturer system, and installer workmanship each carry different durations, exclusions and issuers.
Change order
A documented amendment to the contract covering work not in the original scope. For residential work at or above $10,000, Vermont requires the contract to describe how amendments are approved and for them to be documented in a signed writing.
Ice dam
A ridge of ice at a roof edge, formed when heat escaping into the attic melts snow that refreezes at the cold eave. Water backs up behind it and enters under the covering. The roof can be entirely sound. The cause is in the attic.
Using this when comparing proposals
Take two estimates and mark every term from this page that appears in one and not the other. That difference is usually where the price gap comes from, and it turns an unanswerable question, why is one cheaper, into a specific list you can put to both bidders.
Where a term appears in neither, that is worth asking about too. Ice protection extent, whether step flashing is new, and the decking allowance are three things that materially affect a Vermont roof and are routinely left unstated.
Page last reviewed August 29, 2026.