In waterproofing, the use of a strong acid to remove the surface of concrete to expose the aggregate.
Tag: techniques
Acrylic Coating
A liquid coating system based on an acrylic resin. Generally, a latex-based coating system that cures by air drying.
Air-Blown Asphalt
Asphalt produced by blowing air through molten asphalt to raise its softening point and modify other properties.
Application Rate
The average quantity (mass, volume or thickness) of material applied per unit area.
Apron Flashing
a term used for a flashing located at the juncture of the top of a sloped roof and a vertical wall, chimney or steeper-sloped roof
Asphalt Emulsion
A mixture of asphalt particles and emulsifying agent, such as bentonite clay and water.
Back-Nailing
The practice of nailing the back portion of a roofing ply, steep roofing unit, or other components in a manner so that the fasteners are covered by the next sequential ply, or course, and are not exposed to the weather in the finished roof system.
Also called Blind-Nailing.
Bermuda Seam
A metal panel profile featuring a step-down profile that runs perpendicular to the slope of the roof.
Bitumen Stop
See Envelope or Bleed Sheet
Bleed Sheet
A sheet material used to prevent the migration of bitumen.
Blind-Nailing
The practice of nailing the back portion of a roofing ply, steep roofing unit, or other components in a manner so that the fasteners are covered by the next sequential ply, or course, and are not exposed to the weather in the finished roof system.
Also called Back-Nailing.
Blocking
Sections of wood (which may be preservative treated) built into a roof assembly, usually attached above the deck and below the membrane or flashing, used to stiffen the deck around an opening, act as a stop for insulation, support a curb, or serve as a nailer for attachment of the membrane and/or flashing.
Boot
(1) a covering made of flexible material, which may be preformed to a particular shape, used to exclude dust, dirt, moisture, etc., from around a penetration; (2) a flexible material used to form a closure, sometimes installed at inside and outside corners.
Bridging
(1) when membrane or base flashing is unsupported at a juncture; (2) bridging in steep-slope roofing occurs when reroofing over standard-sized asphalt shingles with metric-sized asphalt shingles.
Broadcast
Uniformly cast or distribute granular or aggregate surfacing material.
Brooming
To improve the embedding of a ply or membrane by using a broom or squeegee to smooth it out and ensure contact with the adhesive under the ply or membrane.
Built-up roof (BUR)
A continuous, semi-flexible roof membrane, consisting of multiple plies of saturated felts, coated felts, fabrics or mats assembled in place with alternate layers of bitumen, and surfaced with mineral aggregate, bituminous materials, a liquid-applied coating or a granule-surfaced cap sheet.
Bun Stock
Large solid box-like structure formed during the production of polystyrene insulation; individual board stock pieces are then cut from the bun.
Butt Joint
A joint formed by adjacent, separate sections of material, such as where two neighboring pieces of insulation abut.
Button Punch
A process of indenting two or more thicknesses of metal that are pressed against each other to prevent slippage between the metal.
Calendar
(1) to press between rollers or plates in order to smooth and glaze or to thin into sheets; (2) a machine for calendering.
Cant Strip
A beveled strip used under flashings to modify the angle at the point where the roofing or waterproofing membrane meets any vertical element.
Capillary Action
(1) the action by which the surface of a liquid where it is in contact with a solid is elevated or depressed depending on the relative attraction of the molecules of the liquid for each other and for those of the solid; (2) the siphoning of liquid into a joint or void between two adjacent surfaces.
Caulking
(1) the physical process of sealing a joint or juncture; (2) sealing and making weather-tight the joints, seams or voids between adjacent surfaces by filling with a sealant.
Cavitation
The formation of a partial vacuum or cavity in a liquid
Closed-Cut Valley
A method of valley application in which shingles from one side of the valley extend across the valley while shingles from the other side are trimmed back approximately 2 inches (51 mm) from the valley centerline.
Coating
A layer of liquid material applied to a surface for protection or appearance.
Coil Coating
The application of a finish to a coil of metal using a continuous mechanical coating process.
Cold Forming
The process of shaping metal into desired profiles without the application of heat.
Cold Rolled
The process of forming steel into sheets, panels, or shapes on a series of rollers at room temperature.
Compatible Materials
Two or more substances that can be mixed, blended, or attached without separating, reacting, or affecting the materials adversely.
Concealed Nail
A method roofing application in which all nails are driven into the underlying course of roofing and covered by a subsequent, overlapping course.
Conditioning
The storage of a material specimen under specified temperature, humidity, etc. for a specified time prior to testing.
Core Cut (Core Sample)
(1) a sample from a low-slope roof system taken for the purpose of obtaining primarily qualitative information about its construction. Typically, core cut analysis can verify or reveal the type of membrane surfacing; the type of membrane; the approximate number of plies; the type, thickness and condition of the insulation (if any); and the type of deck used as a substrate for the roof system. (2) for in SPF-based roof systems, core cuts are used to obtain both quantitative and qualitative information, such as the thickness of the foam, the thickness and adhesion of the coating, thickness of individual passes and adhesion between passes and the adhesion of the foam to its substrate.
Cross-linking
The formation of chemical bonds between polymeric chains. Cross-linking of rubber is referred to as vulcanization or “curing.”
Crystalline Waterproofing
A compound of cement, quartz or silica sand, and other active chemicals that are mixed and packaged for use in a dry powder form; the packaged mixture is then mixed with water and applied to a concrete surface where it penetrates into the pores of concrete.
Cure
A process whereby a material is caused to form permanent molecular linkages by exposure to chemicals, heat, pressure and/or weathering.
Cured Concrete
Concrete that has attained its intended design performance properties.
Dampproofing
treatment of a surface or structure to resist the passage of water in the absence of hydrostatic pressure.
Double Coverage
Application of asphalt, slate, or wood roofing such that the lapped portion is at least 2 inches (50 mm) wider than the exposed portion, resulting in two layers of roofing material over the deck.
Double Pour
To apply two layers or flood coats of bitumen and aggregate to a built-up roof.
Embedment
(1) the process of pressing/positioning a felt, aggregate, fabric, mat, or panel into hot bitumen or adhesive to ensure intimate contact at all points; (2) the process of pressing/positioning granules into coating in the manufacture of factory-prepared roofing, such as shingles.
Emulsion
A mixture of bitumen and water, with uniform dispersion of the bitumen or water globules, usually stabilized by an emulsifying agent or system.
End Lap
The distance of overlap where one ply, pane, or piece extends beyond the end of the immediately adjacent underlying ply, panel, or piece.
Envelope
A continuous membrane edge seal formed at the perimeter and at penetrations by folding the base sheet or ply over the plies above and securing it to the top of the membrane. The envelope prevents bitumen seepage from the edge of the membrane.
Exposed Nail Method
A method of asphalt roll roofing application in which all nails are driven into the adhered, overlapping course of roofing. Nails are exposed to the weather.
Extrusion
A process in which heated or unheated material is forced through a shaping orifice (a die) in one continuously formed shape, as in film, sheet, rod or tubing.
Feathering Strips
Tapered wood filler strips placed along the butt ends of old wood shingles to create a relatively smooth surface when reroofing over existing wood shingle roofs. Referred to in some regions of the country as “horse feathers,” or leveling strips.
Fillet
A heavy bead of waterproofing compound or sealant material generally installed at the point where vertical and horizontal surfaces meet; to reduce the desired effect to take out the 90° angle at the base of a vertical flashing.
Fly-In
Method of application for roll materials by which the dry sheet is set into the bitumen or adhesive applied to the roof surface.
Galvanic Action
An electrochemical action that generates electrical current between two metals of dissimilar electrode potential.
Glaze Coat
(1) the top layer of asphalt on a smooth-surfaced built-up roof membrane; (2) a thin protective coating of bitumen applied to the lower plies or top ply of a built-up roof membrane when application of additional felts or the flood coat and aggregate surfacing are delayed. (also see Flood coat.)
Hand Tabbing
Method of spot applying asphalt-based adhesive to shingles for securement and wind resistance.
Heat Seaming
The process of joining thermoplastic films, membranes, or sheets by heating and then applying pressure to bring both materials in contact with each other. (see Heat welding.)
Heat Welding
Method of melting and fusing together the overlapping edges of separate sheets or sections of polymer modified bitumen, thermoplastics or some uncured thermoset roofing membranes by the application of heat (in the form of hot air or open flame) and pressure. (see Heat seaming.)
Impregnate
In roofing materials manufacture, to completely surround the fibers in a felt or mat with bitumen, with the spaces between the fibers partially or completely filled without a continuous coating of bitumen on the surface.
Infrared Thermography
The process of displaying variations of apparent temperatures (variation of temperature or emissivity or both) over the surface of an object by measuring variations in infrared radiance.
Laminate
To join layers of materials together using fusion; the process of joining layers of materials together using adhesion.
Liquid-Applied
Application of bituminous cements, adhesives or coatings installed at ambient or slightly elevated temperatures.
Masonry
Construction, usually set in mortar, of natural building stone or manufactured units, such as brick, concrete block, adobe, glass block, tile, manufactured stone or gypsum block.
Metallic Waterproofing
Consist of finely graded iron particles combined with an oxidizing catalyst. When mixed with water (or water, cement, and sand), the finely distributed particles expand, creating a waterproof layer that becomes a part of the surface to which it is applied.
Moisture Contour Map
A map used to graphically define the location of moisture within a roof assembly after a moisture scan has been performed
Moisture Scan
The use of a mechanical device (capacitance, infrared, or nuclear) to detect the presence of moisture within a roof assembly. (see Non-destructive testing.)
Mop and Flop
An application procedure in which roofing elements (insulation boards, felt plies, cap sheets, etc.) are initially placed upside down adjacent to their ultimate locations; coated with adhesive or bitumen; and turned over and adhered to the substrate. Mopping: the application of hot bitumen with a mop or mechanical applicator to the substrate or plies of a bituminous membrane. There are four types of mopping. • Solid mopping: a continuous coating. • Spot mopping: bitumen is applied roughly in circular areas, leaving a grid of unmopped perpendicular areas. • Sprinkle mopping: bitumen is shaken onto the substrate from a broom or mop in a random pattern. • Strip mopping: bitumen is applied in parallel bands.
Nailer
A piece or pieces of dimensional lumber and/or plywood secured to the structural deck or walls, which provide a receiving medium for the fasteners used to attach membrane or flashing.
Sometimes called Blocking.
Negative Side Waterproofing
An application wherein the waterproofing system and source of hydrostatic pressure are on opposite sides of the structural element.
Nesting
(1) the installation of new metal roof deck directly on top of existing metal roof deck; (2) a method of reroofing with new asphalt shingles over existing shingles in which the top edge of the new shingle is butted against the bottom edge of the existing shingle.
Night Seal (Night Tie-In)
A material and/or method used to temporarily seal a membrane edge during construction to protect the roofing assembly in place from water penetration. Usually removed when roofing application is resumed.
Nondesructive Testing
A method to evaluate the disposition, strength or composition of materials or systems without damaging the object under test. Typically used to evaluate moisture content in roofing assemblies, the three common test methods are electrical capacitance, infrared thermography and nuclear back-scatter.
Picture Framing
A square or rectangular pattern of ridges in a roof membrane or covering over insulation or deck joints.
Positive Drainage
The drainage condition in which consideration has been made during design for all loading deflections of the deck and additional roof slope has been provided to ensure drainage of the roof area within 48 hours following rainfall during conditions conducive to drying.
Positive Side Waterproofing
An application where the waterproofing systems and the source of the hydrostatic pressure are on the same side of the structural element.
Pre-Tinning
Coating a metal with solder or tin alloy prior to soldering or brazing it.
Racking
A method of asphalt shingle application, also referred to as the straight-up method, whereby shingle courses are applied vertically, up the roof rather than laterally or across and up.
Re-Cover
The addition of a new roof membrane or steep-slope roof covering over a major portion of an existing roof assembly. This process does not involve removal of the existing roofing.
Re-Roofing
The process of re-covering, or tearing-off and replacing an existing roof system
Release Tape (Release Strip)
A plastic film or paper strip that is applied to the back of self-sealing shingles and other materials. The strip prevents the material from sticking together in the roll or bundle. With asphalt shingles, the strip need not be removed for application of the shingles.
Ridge Course
The last or top course of roofing materials, such as tile, roll roofing, shingles, etc., that covers the ridge and overlaps the intersecting field roofing.
Roof Replacement
The practice of removing an existing roof system down to the roof deck and replacing it with a new roofing system.
Scarfed
Shaped by grinding.
Screeding
The process of striking off excess concrete to bring the top surface of the concrete to the proper finish and elevation.
Shingling
(1) the application of shingles; (2) the procedure laying parallel felts so that one longitudinal edge of each felt overlaps and the other longitudinal edge underlaps an adjacent felt. Normally felts are shingled on a slope so that water flows over rather than against each lap.
Skirt Flashing
A formed metal counterflashing secured under a mechanical unit or skylight to cover and protect the upper edge of a base flashing and its associated fasteners
SPF
Spray polyurethane foam
T-Joint
The condition created by the overlapping intersection of three or four sheets in the membrane.
Test Cut
A sample of the roof system or assembly which exposes the roof deck and is used to diagnose the condition of the membrane, evaluate the type and number of plies or number of membranes, or rates of application (e.g., the weight of the average interply bitumen moppings).
Thermal Bridge
The penetration of a material of high thermal conductivity (e.g., a metal insulation or roof membrane fastener) through a material of low thermal conductivity (e.g., thermal insulation); the result is a lowered thermal resistance for the assembly.
Tie-In
In roofing and waterproofing, the transitional seal used to terminate a roofing or waterproofing application at the top or bottom of flashings or by forming a watertight seal with the substrate, membrane, or adjacent roofing or waterproofing system.
Torch-Applied (Torch-Down)
Method used in the installation of polymer modified bitumen membranes characterized by using open flame propane torch equipment.
Transverse Seam
The joint between the top of one metal roof panel and the bottom of the next panel, which runs perpendicular to the roof slope.
Tuckpointing
The process of removing deteriorated mortar from an existing masonry joint and troweling new mortar or other filler into the joint.
Underlayment
An asphalt-saturated felt or other sheet material (may be self-adhering) installed between the roof deck and roof covering, usually used in a steep-slope roof construction. Underlayment is primarily used to separate the roof covering from the roof deck, shed water and provide secondary weather protection for the roof area of the building.
Water Cure
A method of curing a material, such as concrete, by applying a fine mist of water over the surface to control the rate of moisture evaporation from the material.
Waterproofing
Treatment of a surface or structure to prevent the passage of water under hydrostatic pressure.
Wear Course
The top layer of surfacing that carries pedestrian or vehicular traffic. Sometimes referred to as wearing surface.
Weatherproof
The ability of a membrane or roof covering to prevent the passage of water with a limited amount of hydrostatic pressure.
Weld
To join pieces of metal together by heat fusion.
Woven Valley
A method of valley construction in which shingles or roofing from both sides of the valley extend across the valley and are woven together by overlapping alternate courses as they are applied.