Glossary
Roof restoration, in plain words
Keep this open while you read a coating bid, a specification or a moisture scan report: each term defined briefly, A to Z, with a link wherever a guide or page goes further. These are general definitions; on a real job, the product data sheet and the written specification govern.
Jump to: A–D · E–L · M–R · S–Z
A–D
The terms that decide whether a roof can be restored at all start here: the adhesion test patch, the core cut and the deck.
Acrylic coating — A water-based elastomeric coating, usually white, and the usual finish coat on a roof that drains. It is sensitive to water until it cures, can lose adhesion under prolonged ponding, and chalks and slowly loses thickness as it weathers; silicone vs acrylic sets out where each one fits.
Adhesion test patch — A small patch of the actual system put down on the roof with a strip of fabric embedded, left to cure, then pulled to see whether it holds. For Silicone44 the patch cures three days and Uniflex looks for at least 2 lb per inch; a lower result goes to Uniflex, which names the primer. Test more often where the roof is worn, shaded, previously coated or holds water, and nothing else settles whether a coating will bond to this roof: the adhesion test patch.
Alligatoring — A network of deep cracks across a weathered asphalt surface, named for the look of alligator hide. A heavily alligatored smooth built-up or modified bitumen roof is resurfaced with asphalt emulsion and fabric before it is coated.
Aluminum coating — An asphalt-based coating pigmented with aluminum that dries to a silver finish. The current data sheets for the 500 Premium KST020475, 300 Commercial KST020480 and Superbrite KST020418 list metal, smooth built-up, granulated asphalt and granulated or smooth modified bitumen roofs, and name no primer: the roof is pressure-washed and left to dry completely, and the coating goes on at 50 °F or warmer with no rain forecast. The fibered 500 and 300 also go directly over lightly rusted metal: aluminum and asphalt coatings.
Asphalt emulsion — Asphalt dispersed in water, black, used with reinforcing fabric to resurface a smooth built-up or modified bitumen roof that has dried out or alligatored. Fibered asphalt emulsion KST040312 is a resurfacer, not a finish: an elastomeric or aluminum coating goes over it.
ASTM C1153 — The standard practice for locating wet insulation in roofing systems with infrared imaging, from the ground or from the air. Among other things it covers the weather a survey needs, and it requires the infrared findings to be confirmed with cores.
Ballast — Loose stone or pavers laid over a roof membrane to hold it down. Ballast stores the day’s heat and masks the small differences a thermal camera reads, so a thermal scan does not suit a ballasted roof, and it is surveyed another way: cores, a capacitance or nuclear survey, or a walk-through. Gravel set into a built-up roof is a different case, a poor fit for a thermal scan and usually surveyed another way too.
Base coat — The first full coat of an acrylic system across the roof, laid after cleaning, repairs, priming and detailing, with the acrylic finish coat over it; Silicone44 takes no base coat. On an asphaltic roof the MB base coat is the first coat, and on single-ply the single-ply base coat follows the wash primer on EPDM or a pressure wash on TPO, PVC and Hypalon: base coats and primers.
Blister — A raised bubble where a membrane or coating has come away from what is under it, usually with moisture or air trapped inside. Blisters are cut out and repaired before a coating goes on, and trapped moisture is the cause cited first when a coating blisters: why roof coatings fail.
Built-up roof (BUR) — A roof built from alternating layers of asphalt and reinforcing felt, finished smooth, with gravel, or with a granulated cap sheet. Smooth and granulated built-up roofs take the MB base coat and an acrylic finish, or silicone with no base coat, while a gravel surface makes a thermal scan a poor fit: modified bitumen and BUR systems.
Cap sheet — The top ply of a modified bitumen or built-up roof, usually surfaced with mineral granules. A granulated cap sheet takes the same build-ups as a smooth asphaltic roof, and more coating, because the first coat goes into the granules; a cap sheet worn down to the mat across the field is one sign of the widespread membrane failure that rules a roof out.
Capacitance survey — A moisture survey taken on a grid with an electrical impedance scanner, which reads wet and dry from the material’s electrical properties. ASTM D7954 is its standard practice; it does not suit metal or conductive surfaces or black EPDM, and its readings are confirmed with cores: survey methods compared.
Core cut — A small sample cut through the roof assembly that shows how many layers there are, what the insulation is and whether it is wet; weighing it, drying it and weighing it again measures the water it held. Cores confirm what a scan flags, and each one is patched the day it is cut: core samples.
Cover board — A thin, firm board between the insulation and the membrane that protects the insulation and gives the membrane a solid base. It can take on water too, and wet cover board holds heat the way wet insulation does.
Cricket — A small raised section that turns water around an obstacle, such as the back of a curb or rooftop unit, toward a drain. In this line, Slope Builder KST0SLPBD, a 40 lb powder mixed with water on site into a cementitious slurry, builds up low areas before the coating goes on; under silicone, no Uniflex specification names it, so the adhesion test and Uniflex decide.
Curb — The raised frame a rooftop unit, skylight or hatch sits on, flashed into the roof around its base. Curbs are detailed with fabric or tape and sealant before the field is coated, and they are counted at the survey rather than discovered halfway through the job.
Data sheet — The maker’s product data sheet for one product: it names the preparation, the application rate, the temperatures and the cure. We do not print rates or cure times as our own, and on a real job the current data sheet and the written specification govern, not a general reference like this one.
Deck — The structural layer the roof is built on: steel, concrete, wood or gypsum. It has to be sound to carry a restoration, and a deck that is rusted through, rotted or moving underfoot is a question for the building’s engineer: what makes a roof a candidate.
Dew point — The temperature at which moisture in the air condenses on a surface. It matters twice: coatings go only on a surface that is completely dry, dew included, and a thermal scan needs a membrane with no condensation on it: when to coat a roof.
Dry film thickness (DFT) — The thickness of a coat once it has cured, in mils: wet film thickness times volume solids. Data sheets and specifications state it, and wet mils, dry mils and coverage works through the math.
E–L
The membranes a coating goes over, the details where restored roofs are won or lost, and who applies the system.
Elastomeric — Able to stretch and recover as the roof heats, cools and moves. The acrylic elastomeric and solvent-based elastomeric coats in this line carry it in their names, and silicone is a rubber that stretches too.
Emittance — Thermal emittance: how readily a surface gives off the heat it has absorbed, expressed as a fraction. Some energy codes set minimums for it beside solar reflectance, and it matters to a thermal camera too: surfaces that differ in emittance read differently, one reason a warm area on a scan stays a suspect until a core confirms it.
EPDM — A synthetic rubber single-ply membrane, usually black. Under a coating it is cleaned with the wash primer KST038620 and takes either the single-ply base coat KST041321 and an acrylic finish, or Silicone44 with no base coat, with open seams sealed first; black EPDM is the wrong surface for a capacitance survey.
Fastener — A screw or bolt that holds a roof panel or a membrane to the structure below. On a metal roof, loose and rusted fasteners are tightened or replaced first, laps open more than 1/8 in are fastened, and every fastener head is reinforced or striped along with the seams before the field is coated: metal roof systems.
Finish coat — The top coat of the system, the one that faces sun and weather. On a roof that drains it is usually a white acrylic elastomeric; where water stands, silicone or the solvent-based elastomeric: finish coats.
Flashing — The material that seals the joint where the roof membrane meets something else: a wall, a parapet, a curb, a drain or an edge. Flashings are reinforced with fabric or tape before the field is coated: seams, fasteners and flashings.
Fluid-applied — Put down as a liquid, by roller, brush or spray, and cured on the roof into one continuous surface with no laps in it. The model building code defines a roof coating as a fluid-applied, adhered coating used for maintenance, for repair, or as part of a roof covering system.
Granules — The mineral surfacing embedded in a cap sheet. Loose granules bear on whether a coating will hold, which is one reason the adhesion test patch comes first.
Hypalon — A synthetic rubber single-ply membrane (CSPE) found on existing low-slope roofs. Where it drains, it takes the single-ply acrylic system: pressure wash, single-ply base coat KST041321 and an acrylic finish, with butyl seam tape at the details. No Uniflex silicone document covers it, so a Hypalon roof that holds water goes through the quote form, and Uniflex names the primer after an adhesion test.
Infrared thermography — Imaging with a camera that reads surface temperature instead of visible light. In the evening after a sunny day, wet insulation holds the day’s heat longer than dry insulation and shows warmer, but the camera sees temperature differences, not water, and it is the wrong tool on ballasted, heavy-gravel, metal panel, highly reflective or already white-coated roofs, or over closed-cell foam: infrared roof moisture surveys, and will a thermal scan work on this roof.
Installer — The roofing contractor who applies the system; we supply the materials and never do the roofing work ourselves. We work with a network of installers and can introduce you to one anywhere in the US, who looks at the roof and says whether it is a good candidate for restoration: choosing a contractor.
Lap — The overlap where one sheet or ply of a roof meets the next, sealed together. Splits at the laps are a normal repair before coating, laps open along their whole length point to a membrane that has failed, and a finished coating has no laps of its own.
Low-slope roof — A roof with little pitch, often called a flat roof, though it is built to fall toward its drains and scuppers. Commercial low-slope roofs are what these coating systems, and our drone moisture scan, are for: restoration systems by roof type.
M–R
How wet insulation is found, and what a coating system is built from.
Membrane — The layer of a roof that keeps water out: a single-ply sheet, or a built-up or modified bitumen surface. A restoration leaves the existing membrane in place and builds a new continuous surface on it.
Mil — One thousandth of an inch, the unit coating thickness is measured in. A gallon spread over 100 sq ft lays down about 16 wet mils, and spread one mil thick it covers 1,604 sq ft, the arithmetic behind the material estimator.
Modified bitumen — Asphalt modified with SBS or APP polymers and made into reinforced rolls, laid in plies and often finished with a granulated cap sheet. Smooth or granulated, it takes the MB base coat KST041510 and an acrylic finish; where water stands, Silicone44 goes on with no base coat, over Uniflex’s Bleed Blocker Primer where the asphalt is newer or likely to bleed. We do not stock that primer: ask on the quote form.
Moisture scan — The drone moisture scan we arrange for commercial low-slope roofs anywhere in the US: on an evening after a sunny day, once the sun has set, a drone with a thermal camera flies over the roof, and wet insulation shows warmer because it holds the day’s heat longer than dry insulation. You get a map of the roof with any areas that look wet outlined and measured in square feet, video from the flight and a written assessment of what the scan found, and small core samples then confirm the flagged areas. It usually takes one evening, nobody has to walk the whole roof, the building runs as normal, and we fly only with the owner’s go-ahead: how the scan works.
Moisture survey — Any method of finding wet material inside a roof assembly: infrared, capacitance, nuclear or core cuts. Every non-destructive reading is relative, so cores confirm it, and coating makers, Sherwin-Williams included, require wet insulation to be found and replaced before a coating goes on. Uniflex also requires a moisture survey, by a qualified person, on every Uniflex system-warranty project, and a third-party survey for a 15-year warranty request; whether a survey is accepted is Uniflex’s call: from moisture map to restoration scope.
Nuclear moisture survey — A survey with a nuclear gauge that detects the hydrogen in water under the membrane, read on a grid across the roof. It reads several inches deep and can be used where water is ponded; its readings, too, are confirmed with cores, and ANSI/SPRI/IIBEC NT-1 is its standard.
Parapet — The low wall that rises above the roof at its edge. Its flashing is detailed before the field is coated, and where water sits along it, the low area is built up first.
Penetration — Anything that passes through the roof: a pipe, a vent, a conduit, a support. Each one is sealed and reinforced before the field is coated, with sealant, fabric or tape chosen for the substrate. Under silicone, Uniflex’s specifications use its OneFlash sealant at curbs and penetrations, which we do not stock: ask on the quote form.
Pitch pan — A metal pan set around a penetration that cannot be flashed the usual way, such as a cluster of pipes, and filled with sealant. Refilling pitch pans is routine maintenance, and they are detailed before a roof is coated.
Ponding water — Water still standing on a low-slope roof when it should have drained; contractors commonly treat water still there 48 hours after the rain stopped as ponding. Acrylic is not for it and silicone or the solvent-based elastomeric is, but silicone does not fix drainage: Uniflex’s silicone specifications still expect at least 1/4 in per ft of slope and working drains, and long-standing water means more inspection and recoating. The load and the cause are questions for the building’s engineer: ponding water and roof coatings.
Primer — A first coat that prepares a particular substrate for the system, such as rust-inhibitive primer KST034520 on corroded steel. Not every roof needs one: the data sheet and an adhesion test patch decide, and on a low result Uniflex names the primer. Primers by substrate sorts them by roof.
PVC — A thermoplastic single-ply membrane, and a coatable one: Uniflex’s single-ply specifications cover EPDM, TPO and PVC. Weathered PVC takes Silicone44 directly once an adhesion test passes, with no primer and no base coat; for an acrylic finish the single-ply specification covers it too, and the adhesion test settles the build-up. New PVC needs a primer first, so ask us: coating over single-ply.
Recoat — A fresh coat over a coating system that has weathered, renewing the surface without starting again. What can go over an existing coating depends on its chemistry: Silicone44 goes directly over a sound, aged acrylic, silicone or urethane coating once it is washed, loose coating is scraped back and adhesion tests pass: looking after a coated roof.
Recover — Installing a new roof covering over an existing one without removing it. Codes limit how many coverings a roof may carry and bar a recover over a water-soaked roof; how a coating counts varies by code (Florida’s is narrower than the model code), and the local building department decides for the address: coat, cover or tear off, and Florida’s rules.
Reinforcing fabric — Polyester fabric bedded in coating at seams, flashings and penetrations, the middle layer of a three-course detail. It comes 6 in, 12 in and 40 in wide, the widest for reinforcing the field: fabrics and tapes.
Restoration — Renewing a sound low-slope roof in place: clean and repair it, replace any wet insulation, reinforce the seams and details, and coat the whole surface, with no tear-off. Applied over a sound, dry roof, a restoration system adds 10 to 15 years of service life: commercial roof restoration, and the process step by step.
S–Z
What the system is made of, what it costs against a tear-off, and who warrants it.
Scupper — An opening through a parapet or roof edge that lets water off the roof, often into a downspout. Water should leave a low-slope roof at its drains and scuppers, and low areas around them are built up before coating.
Seam tape — Self-adhering tape laid over seams, flashings and penetrations and coated over, such as butyl seam tape KST020804, the one detail product in this line listed for Hypalon. On EPDM, TPO and PVC a fleece-backed bonding tape does the same job at curbs, flashings and gutters.
Silicone coating — A silicone rubber finish coat, one of the two finishes for a roof where water stands; the solvent-based elastomeric is the other. It goes on with no base coat under it, picks up dirt more than other coatings and is slick, so it is not for traffic areas; in this line it is Silicone44 KST044300 (white) or KST044320 (gray).
Solar reflectance — How much of the sunlight striking a surface it reflects instead of absorbing, expressed as a fraction. White finish coats reflect sunlight and keep the roof surface cooler; where an energy code sets a minimum, it counts three-year-aged values, such as those the Cool Roof Rating Council publishes: cool roof ratings.
Solvent-based — Carried in a solvent instead of water, curing as the solvent evaporates. The solvent-based elastomeric base and finish coats in this line are the alternative to silicone where water stands, and they ship as regulated freight.
Spray polyurethane foam (SPF) — Insulating foam sprayed on as a liquid that expands into one seamless layer, then coated and recoated over its life. Once damaged or wet foam is cut out and replaced, sound foam takes an acrylic base coat and finish, or Silicone44 directly with no primer and no base coat, and because closed-cell foam does not hold water the way board insulation does, a thermal scan is the wrong tool on it: spray foam systems.
Square — The roofing trade’s unit of area: 100 square feet. Coating rates are often written in gallons per square, and how much coating works from square feet to gallons.
SRI — Solar Reflectance Index: a single figure calculated from a surface’s solar reflectance and thermal emittance. Some energy codes accept a three-year-aged SRI in place of meeting the two separately.
Substrate — The surface a coating goes onto: metal, single-ply, modified bitumen, built-up, foam or concrete. It decides the primer, the detail materials and, under an acrylic finish, the base coat: the system finder walks through each, and which system for which roof explains why.
System warranty — A warranty on the finished roof system, as distinct from the goods, issued by the coating maker under its own terms. Sherwin-Williams offers its system warranties when one of its authorized contractors applies the system, and inspects the finished roof before it issues one; we supply the materials, which carry the seller’s warranty that they match their description and are free of manufacturing defects when delivered: roof coating warranties.
Tear-off — Removing every layer of a roof down to the deck so a new roof can go on, which codes call replacement. Tearing off and replacing a low-slope roof typically runs $10 to $18 per square foot installed; restoring it with a coating system typically runs $3.50 to $7 per square foot installed, acrylic toward the low end and silicone toward the high end. Both are typical ranges drawn from published industry figures, not a quote: the roof’s condition, how much wet insulation comes out, access and region move them, so run the numbers for the roof in question.
Thermal anomaly — An area that reads warmer or cooler than the roof around it on a thermal image; wet insulation is one cause, and exhausts, ponded water, debris, penetrations and changes in membrane thickness are others, so the scan marks suspects and the cores confirm them. In the anonymized sample from a real scan, the warmest of 28 flagged areas read 14.5 °F above the dry roof around it and nine read less than 5 °F warmer; none was cored, so each is still a suspect, and how to read a thermal roof scan explains the patterns.
Three-course — A detail built in three layers: coating or patching cement, reinforcing fabric bedded into it, and another layer over the fabric. It is how seams, flashings, penetrations and repairs are reinforced before the field is coated, with acrylic patching cement KST041220 one of the materials it is built from.
TPO — Thermoplastic polyolefin, a single-ply membrane with heat-welded seams. Weathered TPO is pressure-washed and takes the single-ply base coat and an acrylic finish, or Silicone44 directly once an adhesion test passes, with no primer and no base coat; the wash primer is for EPDM only, and new TPO needs a primer first: coating over TPO and EPDM.
UNIGUARD — The name of Sherwin-Williams’ system warranty for Uniflex: Sherwin-Williams offers UNIGUARD system warranties of 10 or 15 years when one of its authorized contractors applies the system, and the warranty is Sherwin-Williams’ own, issued under its own terms.
Volume solids — The share of a coating’s volume that stays on the roof once it has cured; the rest is water or solvent that evaporates. Dry film equals wet film times volume solids, so a coating that is half solids by volume cures to about half the thickness it went down at.
Wash primer — A cleaner-primer for EPDM: applied, left for the set time the data sheet gives, then rinsed off, leaving the surface ready for the next coat. In this line it is Bond-It Wash Primer KST038620, for EPDM only and not for white EPDM.
Water-based — Carried in water and curing as the water evaporates, as acrylic coatings and asphalt emulsions are. Water-based acrylic coatings are sensitive to water until they cure and must not freeze in transit or storage.
Watertight — Keeping water out, at a detail or across a whole roof. It describes what a finished seam, flashing or coated surface has to do, not a promise about how long it will; that depends on the roof under it and how it is looked after.
Wet film thickness (WFT) — The thickness of a coat as it goes down, in mils, checked with a wet-film gauge while the coat is still wet. It is what the applicator can measure on the roof, and volume solids turns it into the dry film the data sheet names.
Wet insulation — Roof insulation that has taken on water. A coating cannot dry it; it insulates less and keeps working on the deck and fasteners below, and a roof with wet insulation is not a candidate until that is cut out and replaced: wet roof insulation.
See what is under the membrane before you budget
Owners: send the building’s address, and we quote the scan for that roof and can introduce you to an installer anywhere in the US. Contractors: send the roof type, square footage and site ZIP for a material quote by coat, or ask to join our installer network. We reply within one business day.