Roof Words in Plain English

Graco GH 833

also called 833, gas rig

1. A gas-hydraulic airless rig that Graco lists for roof coatings. 13 horsepower Honda engine, about 4 gallons per minute, up to a .065 inch tip. Built for big roofs and thick material.

Graco GH 733

also called 733

1. The 833's smaller sibling, also gas-hydraulic. Handy when the roof is mid-size or the rig has to ride a lift.

Graco Mark X HD

also called electric rig

1. A heavy-duty electric airless, about 2.2 gallons per minute with tips up to .051 inch. Needs a big generator or a strong circuit.

Graco Mark VII HD

1. A lighter electric airless, about 1.6 gallons per minute with tips up to .047 inch. Good for detail work and smaller jobs.

Spray tip

also called tip, orifice

1. The little nozzle that sets the spray fan. Thicker coatings need bigger tips, so always match the tip to the coating's data sheet.

Acrylic vs urethane in the pump

also called flushing, cleanup

1. Acrylic is water-based and cleans up with water. Urethane is solvent-based and cures from moisture, so it gets flushed with the right solvent and never left sitting in the hose.

Heated hose

also called hose heater

1. Some crews add hose heat so thick coatings keep flowing on cold days. Check the coating's temperature limits first.

Built-up roof (BUR)

also called tar and gravel, gravel roof, three-ply, four-ply

★ The layer cake your grandfather's roofer baked.

1. Layers of felt glued together with hot asphalt or coal tar pitch, usually topped with gravel or a coating. The old-timer of flat roofs, around for more than a century.

Hot mop and the tar kettle

also called kettle, hot mopping

1. The old way: asphalt melted in a heated kettle on the ground, pumped or carried up, and mopped on hot between felts. You see far fewer kettles these days.

Cold tar

also called cold process, cold-applied asphalt, roof cement

1. Asphalt products that go on without heat, out of a pail or a drum. Common for patches and DIY repairs.

Torch down (modified bitumen)

also called mod bit, SBS, APP, rolled roofing

1. Asphalt sheets toughened with rubbery (SBS) or plastic-like (APP) polymers. Torched, mopped, glued or self-stick. In the US since the 1970s.

Smooth vs granulated cap sheet

also called cap sheet, top ply

1. The top layer of a tar roof. Smooth ones need a coating to protect them from the sun; granulated ones come covered in little rock granules.

R-panel

also called PBR panel, through-fastened panel, exposed fastener

1. A ribbed steel panel screwed straight through its face into the framing. Every screw is a sealed hole, until it is not.

Concealed fastener

also called hidden fastener, clip system

1. Panels held by clips under the seams, so no screws poke through the face.

Gauge

also called metal thickness, 22 gauge, 24 gauge, 26 gauge, 29 gauge

★ The only place in life where 22 beats 29.

1. How thick the steel is. Backwards on purpose: the lower the number, the thicker the metal.

Galvalume

also called aluminum-zinc coated steel

1. Steel coated with an aluminum and zinc alloy to fight rust. Common on newer metal buildings.

Galvanized

also called zinc coated, galv

1. Steel coated with zinc. When the zinc wears thin, red rust shows up.

Purlin

also called girt (on walls), roof framing

1. The horizontal framing members the metal panels screw into.

Sidelap

also called side lap, panel lap

1. Where two panels overlap along their long edge. A favorite place for water to sneak in sideways.

Endlap

also called end lap

1. Where one panel overlaps the next going up the slope.

Ridge cap

also called ridge, peak trim

1. The bent metal that covers the top where two roof slopes meet.

Eave

also called eave trim, drip line

1. The low edge of a sloped roof where water runs off.

Rake trim

also called gable trim

1. The trim along the sloped side edges of a roof.

Closure strip

also called foam closure, inside closure

1. Foam shaped like the panel ribs, tucked under trim to keep out wind, water and birds.

Metal roof screw

also called tek screw, self-driller, neoprene washer screw

1. A self-drilling screw with a rubber washer under its head. The washer dries and cracks with age, which is where many metal leaks start.

Oil canning

also called panel waviness

★ It looks wavy because it is a little dramatic.

1. Visible waves in flat areas of metal panels. Mostly cosmetic.

Thermal movement

also called expansion and contraction

1. Metal grows in the heat and shrinks in the cold, every single day. That movement loosens screws and opens seams over time.

Retrofit framing

also called recover framing, metal over metal

1. New framing set over an old metal roof so a new roof can go on top without tearing off the old one.

Wet mils

also called wet film thickness, WFT

1. How thick the coating is the moment it goes on, checked with a notched wet mil gauge.

Solids by volume

also called volume solids, percent solids

★ The part of the bucket that actually stays for dinner.

1. How much of the coating stays on the roof after the water or solvent leaves. Higher solids, more coating left behind.

VOC

also called volatile organic compounds

1. The solvents that evaporate into the air. Rules limit how much a coating can contain.

Aliphatic vs aromatic urethane

also called aliphatic, aromatic

1. Aromatic urethanes are tough but yellow and chalk in sunlight, so they are often used as base coats. Aliphatic urethanes hold their color in the sun and make good topcoats.

Pot life

also called working time

1. How long a mixed two-part product stays usable before it starts to harden in the bucket.

Recoat window

also called recoat time

1. The time after one coat when the next coat bonds best.

Back-rolling

also called back rolling

1. Rolling a coating right after spraying it to push it into the surface and even it out.

Cutting in

also called detail brushing

1. Brushing coating into corners, seams and around penetrations before the big spray.

Overspray

also called drift

★ Nobody wants a white Chevy that started out red.

1. Coating mist that blows where it should not, like onto cars. Wind days are spray-free days.

Mastic

also called roof mastic, brush grade

1. A thick, paste-like coating or sealant used around details and penetrations.

Butyl

also called butyl tape, butyl coating

1. A sticky rubber compound used in tapes and sealants because it stays tacky for years.

Hybrid coating

also called SEBS, silane-terminated

1. Coatings that blend chemistries to borrow the strengths of each.

Chalking

also called chalky surface

1. A powdery layer on aged paint or coating. It has to be cleaned off or the next coat will not stick.

Single-ply

also called membrane roof, sheet roof

1. A roof made of one layer of factory-made sheet: rubber (EPDM), plastic (TPO) or vinyl (PVC).

Mil

also called thousandth of an inch

★ Not a million, not a millimeter. Just very, very thin.

1. One thousandth of an inch, not a millimeter. A 60 mil sheet is about 1.5 millimeters thick.

Reinforced vs unreinforced

also called scrim reinforced

1. Reinforced sheets have fabric (scrim) inside for strength. Many early vinyl failures were unreinforced sheets.

Fleece-back

also called FB, felt-back

1. A membrane with a fuzzy polyester backing, glued down over rough or uneven surfaces.

Heat welding

also called hot-air welding, welded seams

1. Melting the overlap of plastic or vinyl sheets together with hot air and a roller so the seam becomes one piece.

Robotic welder

also called automatic welder, Leister Varimat, walking welder

★ The roomba of roofing, except it melts plastic.

1. A machine that drives itself down a seam and welds it at a steady speed and heat.

Seam probe

also called probing

1. A blunt pick dragged along a welded seam to find gaps.

T-joint patch

also called T-patch

1. A small patch where three sheets meet in a T, the trickiest spot to seal.

Seam tape

also called splice tape

1. The pre-made tape that joins rubber (EPDM) sheets on newer roofs.

Splice adhesive

also called seam glue, contact cement

1. The liquid glue older rubber roofs used at seams. It dries out with time, which is why old rubber seams let go.

Bonding adhesive

also called membrane adhesive

1. Glue that holds a whole membrane down to the board underneath.

Uncured flashing

also called uncured EPDM

1. Soft, stretchy rubber that molds around odd shapes before it cures.

Cover strip

also called stripping

1. A strip of membrane laid over metal edges or seams to seal them in.

XPS

also called extruded polystyrene, pink board, blue board

1. A denser foam board that shrugs off moisture better than EPS.

LTTR

also called long-term thermal resistance

1. A polyiso rating that averages the R-value over 15 years, since foam loses a little over time.

Facer

also called board facing

1. The paper or glass-reinforced skin on each side of a polyiso board.

Compressive strength

also called 20 psi, 25 psi

1. How much weight per square inch a board takes before it crushes. Higher numbers handle foot traffic better.

HD iso

also called high-density polyiso

1. A thin, extra-hard polyiso board used as a cover board.

Perlite board

also called perlite

1. An older cover board made from expanded volcanic glass. It soaks up water if the roof leaks.

Lightweight insulating concrete

also called LWIC, lightweight concrete

1. Concrete poured with foam or air in it as both deck fill and insulation.

Vapor retarder

also called vapor barrier

1. A layer that slows moisture from inside the building from soaking into the roof.

Staggered joints

also called offset layers

1. Two layers of boards laid so the seams do not line up. It stops heat from leaking through the cracks.

Low-rise foam adhesive

also called foam adhesive, bead adhesive

1. Ribbons of foam glue that hold insulation boards down instead of screws.

Thermal bridging

also called cold spots

1. Heat sneaking out through screws or framing that cut through the insulation.

Concrete deck

also called poured deck, precast plank

1. A concrete slab or planks. Strong and heavy, and it does not mind being walked on.

Wood deck

also called plywood deck, plank deck

1. Plywood or boards, common on smaller and older buildings.

Gypsum deck

also called poured gypsum

1. Poured gypsum over forms. It weakens if it stays wet.

Tectum

also called cementitious wood fiber, wood fiber deck

1. Panels of wood fibers bonded with cement, often seen from inside as a textured ceiling.

Deck flutes

also called ribs

1. The valleys in a steel deck. Screws should land on the high ribs, not in the flutes.

Fastener pullout test

also called withdrawal test, pull test

1. Pulling a test screw out of the deck to measure how well it holds before a roof is fastened.

Deck rust

also called rusted deck

1. Steel deck that has rusted from long-term leaks. Bad spots get cut out and plated or replaced.

Internal drain

also called roof drain, interior drain

1. A drain in the middle of the roof that pipes water down through the building.

Overflow drain

also called secondary drain, emergency overflow

1. A backup drain or scupper set a little higher, in case the main drain clogs.

Gutter

also called eave trough

1. The channel along a roof edge that catches water.

Downspout

also called leader, conductor

1. The pipe that carries water from the gutter or scupper to the ground.

Collector box

also called conductor head, leader head

1. The box on the outside wall that catches scupper water and feeds the downspout.

Drain strainer

also called drain dome, drain basket

★ A hairnet for your drain.

1. The cage on top of a drain that keeps leaves and debris out of the pipe.

Sump

also called drain sump

1. A slight dip built around a drain so water heads into it.

Positive drainage

also called proper slope

1. A roof built so water leaves within about two days after rain.

Deflection

also called sag

1. A deck that sags between supports, which creates low spots and ponding.

Base flashing

also called base flash

1. The membrane that turns up from the roof onto a wall or curb.

Counterflashing

also called cap flashing

1. Metal that hangs down from the wall over the base flashing, like a little roof over the seam.

Termination bar

also called term bar

1. An aluminum bar screwed along the top edge of flashing to hold it tight, then sealed.

Reglet

also called flashing slot

1. A groove cut into masonry to tuck counterflashing into.

Curb

also called equipment curb, RTU curb

1. A raised frame that lifts equipment above the roof surface so it can be flashed.

RTU

also called rooftop unit, HVAC unit

1. The heating and cooling unit sitting on your roof.

Penetration

also called roof penetration

1. Anything that pokes through the roof: pipes, vents, conduit, bolts.

Expansion joint

also called EJ, area divider

1. A flexible raised joint that lets a big building move without tearing the roof.

Nailer

also called wood blocking

1. Wood strips at edges and curbs that give edge metal something solid to fasten into.

Pre-formed corner

also called corner boot

1. A factory-molded inside or outside corner piece for membrane roofs.

Skylight

also called roof light

1. A window in the roof. Great for light, notorious for leaks at the curb.

Roof hatch

also called scuttle

1. The trapdoor and ladder that get people onto the roof.

Infrared survey

also called IR scan, thermal scan, FLIR

1. Scanning a roof after sunset with a thermal camera. Wet insulation holds the day's heat and glows warmer.

Nuclear moisture survey

also called nuclear gauge

1. A meter that counts slowed-down neutrons to find water. Safe, but operators are licensed.

Impedance survey

also called capacitance survey, Tramex

1. Meters that sense moisture by changes in electrical properties.

Electronic leak detection

also called ELD, vector mapping

1. Low or high voltage testing that pinpoints holes in a membrane.

Flood test

also called water test

1. Holding water on a small area to see if it leaks. Use with care.

Adhesion test

also called pull test, peel test, test patch

1. A small test patch pulled after it cures to prove a coating bonds to the surface before a whole roof is coated.

Wet mil gauge

also called notch gauge

1. A notched card pressed into wet coating to read its thickness.

Warning line

also called flag line

1. A rope with flags set back from the roof edge to warn workers they are getting close.

Safety monitor

also called spotter

1. A trained person whose only job is watching workers near the edge.

Guardrail

also called rail system

1. A rail around the edge or opening, about waist high.

Skylight screen

also called skylight guard

★ Skylights look like floors from a distance. They are not.

1. A cover over a skylight so nobody falls through it.

Anchor

also called tie-off point, roof anchor

1. A rated attachment point a harness lanyard clips to.

Harness

also called full-body harness

1. The straps a worker wears so a fall arrest system can catch them safely.

PPE

also called personal protective equipment

1. Gloves, glasses, hard hats, respirators, safety shoes.

Heat stress

also called heat illness

1. Black roofs get brutally hot in summer. Water, shade and breaks are part of the job.

Fire watch

also called hot work watch

1. A person who watches for fire during and after torch work.

Material warranty

also called manufacturer warranty

1. The maker's promise about its product, usually with conditions about installation and upkeep.

Workmanship warranty

also called labor warranty, installer warranty

1. The installer's promise about how the roof was put on.

Renewable warranty

also called recoat warranty

1. A coating warranty that can be extended by cleaning and recoating the roof before it runs out.

Transferable warranty

1. A warranty that can pass to the next owner if the building sells. Often for a fee.

Declarations page

also called dec page

1. Page one or two of a policy that lists coverage limits and deductibles.

Deductible

also called wind deductible, percent deductible

1. What you pay before insurance pays. Commercial wind deductibles are often a percent of the building value, not a flat number.

ACV vs RCV

also called actual cash value, replacement cost value

1. Actual cash value pays for the roof minus its age. Replacement cost pays to replace it new.

Adjuster

also called field adjuster, desk adjuster

1. The person who inspects the damage for the insurance company.

Public adjuster

also called PA

1. An adjuster the owner hires to work the claim on the owner's side.

Supplement

also called claim supplement

1. A request to add items the first insurance estimate missed.

Depreciation

also called recoverable depreciation

1. The amount held back for age, sometimes paid after the work is done.

IBC

also called International Building Code

1. The model building code most states adopt. It covers fire ratings, wind and how many roofs can be stacked.

Energy code

also called IECC, ASHRAE 90.1

1. The rules for insulation. Indiana's commercial code still requires R-20 above the roof deck.

Wind zones

also called field, perimeter and corners

1. Roofs get more fastening at the perimeter and even more at the corners, where wind pulls hardest.

Cool roof

also called reflective roof, white roof

1. A roof that reflects sunlight and lets heat escape, so it stays cooler.

Solar reflectance

also called SR

1. How much sunlight a surface bounces away, from 0 to 1.

Thermal emittance

also called emissivity

1. How well a surface lets go of heat it has absorbed.

SRI

also called solar reflectance index

1. One number that combines reflectance and emittance. Higher means cooler.

CRRC

also called Cool Roof Rating Council

1. The group that rates and lists roof products for reflectance and emittance, new and aged.

ENERGY STAR roof

also called Energy Star

1. The federal label for reflective roof products.

FM approval

also called Factory Mutual, FM rated

1. Testing by FM Approvals for fire, wind and hail. Many insurers like to see it.

Class A fire rating

also called UL 790, fire rating

1. The highest fire resistance class for roof coverings.

Sausage gun

also called 20 oz gun, barrel gun, Albion

★ No hot dogs were harmed.

1. A caulk gun that takes foil sausage packs of sealant instead of tubes.

Wire wheel

also called wire brush, cup brush

1. A spinning steel brush on a grinder that knocks off loose rust.

Roof steamer

also called steam cleaner

1. A machine that cleans with steam, handy for softening tar and killing growth.

Squeegee

also called roof squeegee

1. A rubber blade on a pole for spreading thick coatings or pushing water.

Nap roller

also called 3/4 inch nap

1. A thick paint roller for coatings. Thicker nap holds more material.

Chip brush

also called detail brush

1. A cheap disposable brush for cutting in details.

Seam roller

also called silicone roller, brass roller

1. A hand roller that presses welded or taped seams tight.

Magnetic sweeper

also called nail magnet

1. A rolling magnet that picks up screws and metal scraps from the roof and the parking lot.

Generator

also called genny

1. Portable power for welders, electric sprayers and tools.

Hoist

also called ladder hoist, material lift

1. A powered lift that carries materials up a rail or ladder.

Debris chute

also called dumpster chute, trash chute

1. A tube from the roof edge into a dumpster.

Roof cart

also called material cart

1. A wheeled cart for moving buckets and rolls across the roof.

Scope of work

also called scope, SOW

1. The written list of exactly what will be done, with what, and where.

Roof evaluation

also called roof check, inspection

1. Walking the roof, testing it and photographing it before anyone puts a number on it.

Change order

also called CO

1. A signed change to the scope and price after work starts, like replacing wet boards found under the old roof.

Addendum

also called rider, amendment

1. A written addition to a signed proposal.

Deposit

also called down payment

1. The first payment that books your spot on the schedule.

Lien waiver

also called lien release

1. A document saying a supplier or installer has been paid and gives up the right to place a lien.

Certificate of insurance

also called COI

1. Proof that an installer carries insurance. Always ask for one.

W-2 vs 1099

also called employee vs contractor

1. W-2 workers are employees. 1099 workers are independent and handle their own taxes.

Company operations

also called overhead

1. The costs of running the company: insurance, office, trucks, software, safety gear.

Reinvestment capital

also called reinvestment

1. Money put back into equipment, training and growth.

Conklin

1. Coating and membrane maker founded in 1977. Makes Benchmark acrylic, Affinity urethane, Flexion vinyl and Outpost plastic.

Carlisle

also called Carlisle SynTec

1. A major maker of rubber, plastic and vinyl membranes. Bought Henry in 2021.

Henry

1. Coatings and sealants, many sold in home improvement stores. Owned by Carlisle since 2021.

Firestone Building Products

also called Elevate, Amrize

1. Bought by Holcim in 2021 and now part of Amrize.

Duro-Last

1. A vinyl membrane maker bought by Holcim in 2023, now part of Amrize.

GAF

1. A large roofing maker of shingles and commercial membranes.

Johns Manville

also called JM

1. Makes membranes, insulation and cover boards. Owned by Berkshire Hathaway.

Sika Sarnafil

also called Sarnafil

1. A Swiss-owned vinyl membrane maker.

Mule-Hide

1. A product line sold through ABC Supply.

Tremco

1. Roofing and sealant maker.

Gardner

also called Gardner-Gibson

1. Coatings and roof cements, many sold in big box stores.

Karnak

1. Coatings and roof cements.

Polyglass

1. Modified bitumen and underlayment maker.

EternaBond

1. A brand of roof repair tape.

Ames

also called Ames Research Laboratories

1. Elastomeric coatings, often sold for do-it-yourself repairs.

Gaco

1. Silicone roof coatings.

TruFast

1. Roofing fasteners and plates.

Leister

1. Swiss maker of hot-air welders, including robotic seam welders.

FLIR

also called Teledyne FLIR

1. Thermal camera brand.

Tramex

1. Moisture meter brand.

Graco

1. Spray equipment maker.