Roofing Consultants

Roofing expert witness services


 
The roofing and waterproofing experts at BHA are among the most highly regarded roofing expert witnesses in the construction forensics community. State-licensed professionals working in connection with the firm’s architectural, general contracting, and engineering resources afford clients a comprehensive claims support solution geared toward the rapid resolution of roofing and waterproofing claims. The roofing consultants group are currently designated experts in a number of residential, commercial, and government litigation projects throughout the country.

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Kevin Heidelberger KEVIN HEIDELBERGER
Licensed Roofing Contractor, C39-539648, State of California
Licensed Roofing Contractor (C15A), State of Nevada
Certified Waterproofing Applicator
Instructor – Tile Roof Institute
Member, Tile Roof Institute
Member, Western States Roofing Contractors Association (WSRCA)
Certified Installer – Tile Roof Institute
Certified Specifier – Tile Roof Institute
Carlisle Waterproofing – Certified Inspector

 
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Bradley W. Hughes BRADLEY W. HUGHES
Licensed General Building Contractor, B-00723912, State of California
Licensed Roofing Contractor, C39-00723912, State of California
Graduate, Control Data Institute, Anaheim, CA
Associate of Science Equivalence Diploma computer technology
Member, Construction Specifications Institute
Tile Roofing Institute Certification

 
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Roofing Expert Witness and Consulting Information


A summary of roofing materials commonly utilized in residential construction, assembled by the BHA Roofing Expert Witness Consultants Group


Asphalt Shingles
If you can't afford the high cost of clay tile or slate roofs, the most popular and least expensive is the asphalt roofing shingle. These are the most popular roofing material. They come in two types - organic, and non-organic, which is fiberglass. They follow strict guidelines for manufacture. They come in a variety of colors and durability. They are seen on homes in every part of the country. The biggest downfall of this shingle is its vulnerability to wind and ice damage.

Clay Tile Roofs
Clay is a good roofing material regardless of where it is located, and is resistant to insects, mold and decay, won't burn, and will often outlast the decking it is built upon. You will see this roof on homes with a southwestern, Italian, or Spanish Mission design. This style is more prevalent in California.

Slate Roofs
Slate is another roofing material that is long lasting and near indestructible. Seeing a roof that is slate and 100 years old is not uncommon. This type of roof is often seen in New England. It is as resistant to outside influences as clay tile, and is also extremely heavy

Wooden Shingles
Wooden shingles are a good roofing material generally made from Western Red Cedar. Cedar is resistant to rot and decay. It comes in two types depending on manufacturer. There is a hand sawn and tapered shingle, called a shake, and a shingle that is sawn.

Metal Roofs
In the late 1700s, zinc, copper, and lead were the most popular materials used for roofing. They lasted for decades, but are extremely expensive to build. Today, we see Galvanized or Galvalume Steel roofs. Galvanized is the most popular, and Galvalume is used in the South where hurricanes are common. It is resistant to fire, insects, mildew and rot. These roofs are often seen in climates that get a lot of snow.

Roof system types


Roof systems and materials generally are divided into generic classifications: low slope and steep slope. Low slope roofing includes water impermeable, or weatherproof, types of roof membranes installed on slopes less than or equal to 3:12 (14 degrees). Steep slope roofing includes watershedding types of roof coverings installed on slopes exceeding 3:12 (14 degrees).

Low-slope roofing

There are five generic classifications of low slope roof membranes or systems. Click on a roof system for more information. Most low-slope roof membranes have three principle components: With some roof membranes, a component may perform more than one function.

Built-up roof (BUR) membranes


Contact the roofing expert witness group to discuss your issues concerning built-up roof (BUR) membranes.

Click on a topic for more information. Material and system description

Built up roof membranes, referred to by the acronym BUR, have been in use in the U.S. for more than 100 years. These roof systems are commonly referred to as "tar and gravel" roofs. BUR systems generally are composed of alternating layers of bitumen and reinforcing fabrics that create a finished membrane. The number of plies in a cross section is the number of plies on a roof: The term "four plies" denotes a four ply roof membrane construction. Sometimes, a base sheet, used as the bottommost ply, is mechanically fastened. Built up roofs generally are considered to be fully adhered if applied directly to roof decks or insulation.

The reinforcing fabrics also are called roofing felts or ply sheets. Roofing felts are reinforced with either glass-fiber mats or organic mats. Felts are produced in a standard width of 36 inches and metric width of about one meter.

The bitumen typically used in BUR roof systems is asphalt, coal tar or cold-applied adhesive. The asphalt or coal tar is heated in a kettle or tanker and then applied by mop or mechanical spreader. Asphalt is a petroleum product refined from crude oil; coal tar is derived from the distillation of coal. Cold-applied adhesives typically are solvent-based asphalts that don't have to be heated in a kettle or tanker.

Surfacings for built up roof systems include aggregate (such as gravel, slag or mineral granules), glass-fiber or mineral surfaced cap sheets, hot asphalt mopped over the entire surface, aluminum coatings or elastomeric coatings.


Photo of an aggregate-surfaced BUR

A roof system composed of a built up roof membrane with two or three plies and a polymer-modified bitumen membrane cap sheet is commonly referred to as "hybrid" system. the National Roofing Contractors Association considers this type to be a polymer modified bitumen membrane system.

Material standards

the National Roofing Contractors Association does not make any recommendations about which product or manufacturer to use; however, the National Roofing Contractors Association does recommend that bitumens, felts and mats used for BUR systems meet standards establish by the American Society for Testing and Materials (ASTM).

The following is a list of ASTM standards for the more commonly referenced. Warranties

When purchasing a new roof system, there will be two warranties to consider. First, there will be the manufacturer's warranty. In general, these warranties cover defects in the manufacture of the roof membrane. Please read the National Roofing Contractors Association's consumer advisory bulletin addressing roofing warranties for more information. Once the project is complete, the contractor should provide the customer with a certificate for their records.

Second, the roofing contractor will provide a warranty covering his workmanship. Typically, this will cover installation and related issues. The warranty should contain what items are covered and what will void them. Many contractors offer one year or two years of coverage; however, there is no industry standard.

Metal panel roof systems for low-slope applications


Our roofing expert witnesses have provided consultation to a variety of clients concerning metal panel roof systems issues.

Click on a topic for more information. Metal panel roof system description

There is only one category of metal roof systems used in low-slope applications — structural metal panel. Structural metal panel roof systems can be used for low slope roofs because of their hydrostatic, or water barrier, characteristics. It is important to note structural metal panel roof systems can be used for steep slope roof assemblies, too.

Most structural metal panel roof systems are designed to resist the passage of water at laps and other joints, as sealant or anti capillary designs can be used in the seams. Structural metal panel roof systems possess strength characteristics that allow them to span supporting members.


Example of a structural metal panel roof system

Roof deck

Structural metal panel roof systems are installed over a large variety of substrates. There are two general categories of substrates: one is continuous or closely spaced decking that provides solid support for the metal roof panel, and the other is composed of spaced structural supports (such as purlins) where the metal panels must span between supports. Most structural metal panels are used over spaced structural supports without being supported by a solid roof deck.

Underlayment

Underlayment (or "felt paper" as it is frequently called) is installed over the roof deck before the application of a metal panel roof system. An underlayment performs two primary functions: it provides temporary weather protection until the metal panel roof is installed, and it provides a secondary weatherproofing barrier if moisture infiltrates the metal roof panels.

Underlayments typically are not used with structural metal panel roof systems when intermittent supports are used to carry the roof systems. However, if there is a continuous or closely spaced roof deck, the National Roofing Contractors Association recommends an underlayment be installed.

Asphalt saturated, nonperforated organic felts are among the most common underlayments used for metal roof systems; they commonly are designated as Type 15 and Type 30 or referred to as No. 15 and No. 30, which are reflective of a once used pound per square weight designation. The terms Type I and Type II now are used within the industry in lieu of No. 15 or No. 30, respectively.

If an underlayment is to be installed, the National Roofing Contractors Association recommends a minimum of one layer of No. 30 asphalt-saturated felt applied horizontally in shingle fashion on roof decks having a slope of 4:12 (18 degrees) or more. For roof decks having slopes of 3:12 (14 degrees) up to 4:12 (18 degrees), a minimum of two layers of No. 30 asphalt-saturated underlayment should be applied horizontally in shingle fashion.

In locations where the average temperature for January is 30º F or less, the National Roofing Contractors Association suggests installation of an ice-dam protection membrane. An ice-dam protection membrane generally is a self-adhering polymer-modified bitumen membrane.

An ice dam protection membrane should be applied starting at a roof's eaves and extending upslope a minimum of 24 inches from the exterior wall line of a building. For slopes less than 4:12 (18 degrees), a minimum of 36 inches is recommended. See Figure 1.


Figure 1 - Example of ice damming

the National Roofing Contractors Association also recommends a slip sheet be installed over the underlayment for metal panel roof systems. A slip sheet is a layer of smooth building paper, such as rosin-sized or unsaturated building paper. Its purpose is to protect the underlayment from damage, as the panels can adhere to and tear the underlayment.

Vapor retarders, insulation and ventilation

Condensation should be expected to develop on the undersides of metal roof panels. Careful consideration should be paid to vapor retarder, insulation and ventilation issues. Because every building is in some way unique, building owners and designers may need to consult moisture-control specialists.

Material standards

the National Roofing Contractors Association does not make any recommendations about which product or manufacturer to use; however, the National Roofing Contractors Association does recommend that metal roof systems meet standards established by the American Society for Testing and Materials (ASTM). Warranties

When purchasing a new roof system, there will be two warranties to consider. First, there will be the manufacturer's warranty. In general, these warranties cover defects in the manufacture of the roof covering. In the case of metal panel roofs, manufacturers tend to cover only the metal finishes or coatings. Please read the National Roofing Contractors Association's consumer advisory bulletin addressing roofing warranties for more information. Once the project is complete, be sure the contractor provides you with a certificate for your records.

Second, the roofing contractor will provide you with a warranty covering his workmanship. Typically, this will cover installation and related issues. The warranty should contain what items are covered and what will void them. Many contractors offer one year or two years of coverage; however, there is no industry standard.

Polymer-modified bitumen sheet membranes


The Roofing Expert Witness group at BHA has extensive knowledge and testimony experience concerning polymer-modified bitument sheet membranes and roofing systems.

Click on a topic for more information. Material and system description

Polymer-modified bitumen or modified bitumen (MB) sheet membranes were developed in Europe in the early 1960s and have been in use in the U.S. since the mid 1970s. Polymer-modified roof membranes are composed of reinforcing fabrics that serve as carriers for the hot polymer-modified bitumen as it is manufactured into a roll material. MB roof system membranes are composed of multiple layers, much like BUR membranes. MB roof systems typically are installed as a two-ply system and almost always are fully adhered.

There are two types of MB roofing membranes: Generally, APP modifiers impart a "plasticized" quality to asphalt, and SBS modifiers impart a "rubberized" quality to asphalt. MB membranes and EPDM, a thermoset membrane, often are confused by consumers because of colloquialisms used by roofing contractors. MB and EPDM membranes are sometimes called "rubber roofs."

Surfacings for MB membranes include aggregate surfacing, mineral surfacing, metal foil-laminate surfacing and smooth liquid-applied surfacing.


Photo of a mineral-surfaced MB roof system

A roof system composed of a built up roof membrane with 2 plies or 3 plies and a polymer-modified bitumen membrane cap sheet is commonly referred to as "hybrid" system. the National Roofing Contractors Association considers this type to be a polymer modified bitumen membrane system.

Material standards

the National Roofing Contractors Association does not make any recommendations about which MB products or manufacturer to use; however, the National Roofing Contractors Association does recommend that MB meet standards established by the American Society for Testing and Materials (ASTM). The following ASTM standards are applicable to APP polymer modified bitumen and SBS polymer modified bitumen products.

APP polymer modified bitumen products: SBS polymer modified bitumen products: Warranties

When purchasing a new roof system, there will be two warranties to consider. First, there will be the manufacturer's warranty. In general, these warranties cover defects in the manufacture of the roof membrane. Please read the National Roofing Contractors Association's consumer advisory bulletin addressing roofing warranties for more information. Once the project is complete, be sure the contractor provides you with a certificate for your records.

Second, the roofing contractor will provide you with a warranty covering his workmanship. Typically, this will cover installation and related issues. The warranty should contain what items are covered and what will void them. Many contractors offer one year or two years of coverage; however, there is no industry standard.



Single-ply membranes


Thermoplastic membranes


The roofing expert witness group is prepared to discuss your issues concerning thermoplastic membranes

Click on a topic for more information. Material and system description

Thermoplastic materials are distinguished from thermoset materials in that there is no chemical crosslinking. These membranes can be repeatedly softened by heating or hardened when cooled. Because of the materials' chemical nature, thermoplastic membranes typically are seamed by heat welding with hot air or solvent welding.

There are five common subcategories of thermoplastic roof membranes. The most common thermoplastic roof membranes are PVC and TPO. The following provides general descriptions of these two systems.

Polyvinyl Chloride (PVC)

PVC sheets are produced by calendaring, spread coating or extruding, and typically are reinforced with polyester or glass-fiber mats or scrim. PVC sheets contain plasticizers and stabilizers, as well as other additives to impart flexibility and achieve other desired physical properties. Some membranes are available with nonwoven fleece backing adhered to the underside of a sheet. Thermoplastic Olefin (TPO)

TPO membranes are produced by calendering with lamination, extrusion with lamination, or extrusion-coating techniques. TPO sheets are a blend of polypropylene and ethylene propylene polymers and usually are reinforced with polyester. TPO sheets contain colorant, flame retardants, UV absorbers and other proprietary substances to achieve desired physical properties.
Example of a TPO roof system

PVC and TPO roof membranes can be installed fully adhered, mechanically attached or ballasted. Most PVC and TPO membranes do not receive surfacings.

Material standards

the National Roofing Contractors Association does not make any recommendations about which TP product or manufacturer to use; however, the National Roofing Contractors Association does recommend that TP products meet standards established by the American Society for Testing and Materials (ASTM). Warranties

When purchasing a new roof system, there will be two warranties to consider. First, there will be the manufacturer's warranty. In general, these warranties cover defects in the manufacture of the roof membrane. Please read the National Roofing Contractors Association's consumer advisory bulletin addressing roofing warranties for more information. Once the project is complete, be sure the contractor provides you with a certificate for your records.

Second, the roofing contractor will provide you with a warranty covering his workmanship. Typically, this will cover installation and related issues. The warranty should contain what items are covered and what will void them. Many contractors offer one year or two years of coverage; however, there is no industry standard.

Thermoset membranes


Click on a topic for more information. Material and system description

Thermoset membranes incorporate principal polymers that are chemically cross linked or vulcanized. Membranes that are vulcanized also may be referred to as "cured." One characteristic of true thermoset polymers is once they are cured, they only can be bonded to similar materials with adhesives.

There are five common subcategories of thermoset roof membranes: The most common thermoset roof membrane is EPDM. EPDM principally is composed of two compounds, ethylene and propylene, that are derived from oil and natural gas. The following are some characteristics of EPDM roof membranes: EPDM roof membranes can be installed fully adhered, mechanically attached (using batten bars) or ballasted. Most EPDM membranes do not receive surfacings.


Example of a fully adhered EPDM roof system


Example of a ballasted EPDM roof system

EPDM and polymer-modified bitumen membranes often are confused by consumers because of colloquialisms used by roofing contractors. Contractors commonly call both of these membranes "rubber" roofs. However, in most cases, when contractors specify rubber roofs, they are referring to EPDM.

Material standards

the National Roofing Contractors Association does not make any recommendations about which TS product or manufacturer to use; however, the National Roofing Contractors Association does recommend that TS products meet standards established by the American Society for Testing and Materials (ASTM). Warranties

When purchasing a new roof system, there will be two warranties to consider. First, there will be the manufacturer's warranty. In general, these warranties cover defects in the manufacture of the roof membrane. Please read the National Roofing Contractors Association's consumer advisory bulletin addressing roofing warranties for more information. Once the project is complete, be sure the contractor provides you with a certificate for your records.

Second, the roofing contractor will provide you with a warranty covering his workmanship. Typically, this will cover installation and related issues. The warranty should contain what items are covered and what will void them. Many contractors offer one year or two years of coverage; however, there is no industry standard.

Spray polyurethane foam-based (SPF) roof systems


Click on a topic for more information. Material and system description

SPF-based roof systems are constructed by mixing and spraying a two-component liquid that forms the base of an adhered roof system. SPF can be installed in various thicknesses to provide slope to drain or meet a specified thermal resistance (R-value). A protective surfacing is then applied to the foam to provide protection from the elements.

The first component of an SPF-based roof system is rigid, closed cell, spray polyurethane foam insulation. The foam is composed of two components: isocyanate and polyol. Transfer pumps are used to get the components to a proportioning unit that properly meters the two at a one to one ratio and heats and pumps them through dual hoses. The components are mixed at the spray gun, which is used to apply them to a substrate.

The second component, the protective surfacing, typically is a spray applied elastomeric coating, though hand and power rollers can be used. The protective surfacing also can be a membrane, such as a fleece backed thermoset single ply membrane. The purpose of the surfacing is to provide weatherproofing, protect the foam from UV exposure, provide protection from mechanical damage and assist with the fire-resistant characteristic of the roof system.

The generic types of coatings used on SPF-based roof systems include: Mineral granules or sand may be broadcast into a coating to provide increased surface durability and aesthetic value.

The chemicals used to produce polyurethane foam compounds are manufactured or blended to perform in various temperature ranges. Manufacturers of spray polyurethane foam based roof systems offer materials in different reaction profiles. Profile change is created by altering the chemical ingredients, usually with a catalyst, to compensate for ambient temperature changes. Conditions such as wind speed, sunlight, surface moisture, humidity and temperature of the substrate can affect the reaction of the polyurethane foam.


Example of an SPF-based roof system

Material standards

the National Roofing Contractors Association does not make any recommendations about which SPF products or manufacturer to use; however, the National Roofing Contractors Association does recommend that SPF products meet standards established by the American Society for Testing and Materials (ASTM). Warranties

When purchasing a new roof system, there will be two warranties to consider. First, there will be the manufacturer's warranty. In general, these warranties cover defects in the manufacture of the roof membrane. Please read the National Roofing Contractors Association's consumer advisory bulletin addressing roofing warranties for more information. Once the project is complete, be sure the contractor provides you with a certificate for your records.

Second, the roofing contractor will provide you with a warranty covering his workmanship. Typically, this will cover installation and related issues. The warranty should contain what items are covered and what will void them. Many contractors offer one year or two years of coverage; however, there is no industry standard.


Steep-slope roofing

There are six generic classifications of steep slope roof coverings. Click on a roof covering type for more information. Steep-slope roof systems typically are composed of individual pieces or components installed in shingle fashion. Steep-slope roof assemblies typically consist of three primary parts:

Asphalt shingles


Click on a topic for more information. Material description

Asphalt shingles are composed of: a base material, either organic felt or glass-fiber mat, that provides support for the weather-resistant components and gives a shingle strength; asphalt and fillers; and surfacing material, generally in the form of mineral granules, that provides protection from impact and UV degradation and improves fire resistance.

The most common form of asphalt shingles are strip shingles. They are rectangular, the most prevalent size being 12 inches wide by 36 inches long. Metric shingles are 13-1/4 inches by 39-3/8 inches. Strip shingles most frequently have three tabs that are exposed along the length of the shingle for visual effect and are called 3 tab strip shingles.

Shingles may be produced in a single layer or two or more layers. The latter generally are known as laminated strip shingles, or architectural shingles, and they have a three dimensional appearance.

Both 3-tab asphalt shingles and laminated asphalt shingles contain a strip of factory applied adhesive that is activated by the sun's heat after installation and seals each shingle to the next course. The seal strip also provides much of a shingle's resistance to wind uplift. Some shingles have a strip of cellophane applied to each shingle to prevent the sealing strips from bonding the shingles together when packaged. When the shingles are installed, the self-sealing strips will not align with the cellophane strips and will bond to adjacent shingles. For this reason, the cellophane strips do not have to be removed.

Roof deck

the National Roofing Contractors Association recommends that asphalt shingles be applied over continuous or closely spaced wood plank decking or wood decking. The most common materials used for roof decks are plywood or oriented strand board (OSB). When plywood is used, the National Roofing Contractors Association recommends the use of a minimum 15/32 thick or ½ inch nominal exterior-grade plywood for 16-inch rafter spacings and 5/8 inch nominal thickness for 24-inch rafter spacings. For OSB, the National Roofing Contractors Association recommends using a minimum 15/32 inch thick or ½ inch nominal exterior-grade OSB for 16-inch rafter spacings.

Caution should be exercised when roof decks are constructed out of the following materials: Underlayment

Underlayment (or "felt paper" as it is frequently called) is installed over the roof deck before the application of asphalt shingles. An underlayment performs two primary functions: it provides temporary weather protection until the asphalt shingles are installed, and it provides a secondary weatherproofing barrier if moisture infiltrates the asphalt shingles.

It is not uncommon for it to rain after the contractor installs underlayment but before he installs the asphalt shingles. The underlayment gets wet and becomes wrinkled. If the wrinkling isn't severe enough to affect the shingle installation (i.e. the wrinkling won't telegraph through the shingles and they won't appear buckled or wavy once installed), the underlayment probably can remain in place. The effects of wrinkling also will be minimized by using heavier weight shingles.

Asphalt saturated, nonperforated organic felts are among the most common underlayments used for shingles; they commonly are designated as Type 15 and Type 30 or referred to as No. 15 and No. 30, which are reflective of a once used pound per square weight designation. The terms Type I and Type II now are used within the industry in lieu of No. 15 or No. 30, respectively.

Another type of underlayment is a synthetic underlayment. It is characterized as being lightweight, water-resistant and less likely to wrinkle; having high tear strength; and being easy to walk on—even when wet. Theoretically, the product may be left exposed to the elements for extended periods of time. Although synthetic underlayments and their purported attributes seem appealing, there are significant issues to consider before using them. To date, there are no applicable ASTM standards for these products. Many synthetic underlayments do not meet current building code requirements, so manufacturers need to obtain a code evaluation report for code compliance. And use of these underlayments may void some manufacturers' material warranties for certain roof coverings (such as with asphalt shingles).

the National Roofing Contractors Association recommends a minimum of one layer of No. 15 asphalt-saturated felt applied horizontally in shingle fashion on roof decks having a slope of 4:12 (18 degrees) or more. For roof decks having slopes of 3:12 (14 degrees) up to 4:12 (18 degrees), a minimum of two layers of No. 15 asphalt-saturated underlayment should be applied horizontally in shingle fashion. It should be noted that one layer of No. 30 asphalt-saturated underlayment is not the same as two layers of No. 15.

In locations where the average temperature for January is 30º F or less, the National Roofing Contractors Association suggests installation of an ice-dam protection membrane. An ice-dam protection membrane generally is a self-adhering polymer-modified bitumen membrane.

An ice dam protection membrane should be applied starting at a roof's eaves and extending upslope a minimum of 24 inches from the exterior wall line of a building. For slopes less than 4:12 (18 degrees), the National Roofing Contractors Association recommends a minimum of 36 inches. See Figure 1.


Figure 1 - Example of ice damming

Fasteners

the National Roofing Contractors Association recommends roofing nails be 11-gauge or 12-gauge galvanized steel or the equivalent corrosion-resistant roofing nails. Nail heads should be low-profile, smooth and flat. Shanks should be barbed or otherwise deformed for added pull-out strength. Nails should be long enough to penetrate through all layers of roofing materials and extend through the underside of the roof deck or penetrate at least ¾ inch into wood plank or board decks.

Flashings

Flashings for asphalt shingle roof systems fall into four categories: perimeter edge metal, penetrations, valleys and vertical surfaces. See Figure 2.
Figure 2 - Basic sheet metal flashing components

Apron, step and cricket flashings require some form of counterflashing to cover and protect the top edges from water intrusion. In many cases, the wall covering or cladding material acts as counterflashing. When this does not occur, a metal counterflashing mounted to the vertical surface should be installed. See Figures 3, 4 and 5 for examples.


Figure 3 - Example of metal counterflashing inset in masonry mortar joint



Figure 4 - Example of through-wall metal counterflashing embedded in masonry mortar joint



Figure 5 - Example of surface-mount metal counterflashing

Material standards

the National Roofing Contractors Association does not make any recommendations about which shingle product or manufacturer to use; however, the National Roofing Contractors Association does recommend asphalt shingles meet standards established by the American Society for Testing and Materials (ASTM). Warranties

When purchasing a new roof system, there will be two warranties to consider. First, there will be the manufacturer's warranty. In general, these warranties cover defects in the manufacture of the roof covering. The period of coverage can range from 20 years to a lifetime. Please read the National Roofing Contractors Association's consumer advisory bulletin addressing roofing warranties for more information. Once the project is complete, be sure the contractor provides you with a certificate for your records.

Second, the roofing contractor will provide you with a warranty covering his workmanship. Typically, this will cover installation and related issues. The warranty should contain what items are covered and what will void them. Many contractors offer one year or two years of coverage; however, there is no industry standard.

Clay tile and concrete tile


Click on a topic for more information. Material description

Clay tile is produced by baking molded clay into tile. The density of the clay is determined by the length of time and temperature at which it is heated. Tiles may be glazed and also may have surface texture treatments applied. As a result, there are a wide variety of tile profiles, styles, finishes and colors available. In addition, each tile may have separate field, ridge, hip, gable and terminal tiles of various shapes. Installation methods depend on the nature of the tile being installed; that is, whether it is two piece, one piece, interlocking or flat.


Example of a clay tile roof

Concrete tiles are made of portland cement, sand and water in varying proportions. The material is mixed and extruded on molds under high pressure. The exposed surface of a tile may be finished with cementitious material colored with synthetic oxide additives. The tiles are cured to reach the required strength. They generally have lugs on their undersides for anchoring to batten strips. There are additional waterlocks or interlocking ribs on the longitudinal edges that impede movement and prevent water infiltration.

As with clay tile, there are a wide variety of profiles, styles, finishes and colors available. Color may be added to the surface of a tile or dispersed throughout (color through). Special texture may be added in surface treatment. In addition, each tile type may have separate field, ridge, hip, gable and terminal tiles that are various shapes.

Roof deck

the National Roofing Contractors Association recommends tile roof systems be applied over continuous wood decking. When plywood is used, the National Roofing Contractors Association recommends the use of a minimum 5/8 thick nominal exterior-grade plywood.

Caution should be exercised when roof decks are constructed out of the following materials: For some types of tile roofs, batten and counter-batten systems are used to hang tile that has head lugs. Battens are spaced according to the length and exposure of the specified tile. Battens should be fastened to the deck with 8d common, galvanized, corrosion-resistant nails at approximately 12 inches on center.

Underlayment

Underlayment (or "felt paper" as it is frequently called) is installed over the roof deck before the application of tile. An underlayment performs two primary functions: it provides temporary weather protection until the tile is installed, and it provides a secondary weatherproofing barrier if moisture infiltrates the tile roof covering. Many tile roofs have outlived the underlayment felts over which they were installed. Therefore, an underlayment's service life should be comparable to the design service life of the tile roof covering.

Asphalt saturated, nonperforated organic felts are among the most common underlayments; they commonly are designated as Type 15 and Type 30 or referred to as No. 15 and No. 30, which are reflective of a once used pound per square weight designation. The terms Type I and Type II now are used within the industry in lieu of No. 15 or No. 30, respectively.

Another type of underlayment is a synthetic underlayment. It is characterized as being lightweight, water-resistant and less likely to wrinkle; having high tear strength; and being easy to walk on—even when wet. Theoretically, the product may be left exposed to the elements for extended periods of time. Although synthetic underlayments and their purported attributes seem appealing, there are significant issues to consider before using them. To date, there are no applicable ASTM standards for these products. Many synthetic underlayments do not meet current building code requirements, so manufacturers need to obtain a code evaluation report for code compliance.

the National Roofing Contractors Association recommends a minimum of one layer of No. 30 asphalt-saturated felt applied horizontally in shingle fashion on roof decks having a slope of 10:12 (40 degrees) or more. For roof decks having slopes of 4:12 (18 degrees) up to 10:12 (40 degrees), a minimum of two layers of No. 30 asphalt-saturated underlayment should be applied horizontally in shingle fashion. the National Roofing Contractors Association does not recommend installing tile roof systems on roof slopes less than 4:12 (18 degrees).

In locations where the average temperature for January is 30º F or less, the National Roofing Contractors Association suggests installation of an ice-dam protection membrane. An ice-dam protection membrane generally is a self-adhering polymer-modified bitumen membrane.

An ice dam protection membrane should be applied starting at a roof's eaves and extending upslope a minimum of 24 inches from the exterior wall line of a building. For slopes less than 4:12 (18 degrees), the National Roofing Contractors Association recommends a minimum of 36 inches. See Figure 1.


Figure 1 - Example of ice damming

Securement methods

Many different types and combinations of securement methods are used for the various types of roof tile. To select a method of securement, many conditions need to be considered: wind, deck type, seismic considerations, slope, building codes, local practices and manufacturer recommendations. Fasteners should be made of noncorrosive materials that will remain serviceable in the intended environment for the roof's design life. Flashings

Flashings for tile roofs fall into four categories: perimeter edge metal, penetrations, valleys and vertical surfaces. See Figure 2.
Figure 2 - Basic sheet metal flashing components

Apron, step and cricket flashings require some form of counterflashing to cover and protect the top edges from water intrusion. In many cases, the wall covering or cladding material acts as counterflashing. When this does not occur, a metal counterflashing mounted to the vertical surface should be installed. See Figures 3,4 and 5 for examples.


Figure 3 - Example of metal counterflashing inset in masonry mortar joint


Figure 4 - Example of through-wall metal counterflashing embedded in masonry mortar joint


Figure 5 - Example of surface-mount metal counterflashing

Material standards

the National Roofing Contractors Association does not make any recommendations about which tile or manufacturer to use; however, the National Roofing Contractors Association does recommend clay tile roof coverings meet American Society for Testing and Materials (ASTM) Standard C1167, "Standard Specification for Clay Roof Tiles."

Currently, there are no ASTM standards for concrete tile.

Warranties

When purchasing a new roof system, there will be two warranties to consider. First, there will be the manufacturer's warranty. In general, these warranties cover defects in the manufacture of the roof covering. Please read the National Roofing Contractors Association's consumer advisory bulletin addressing roofing warranties for more information. Once the project is complete, be sure the contractor provides you with a certificate for your records.

Second, the roofing contractor will provide you with a warranty covering his workmanship. Typically, this will cover installation and related issues. The warranty should contain what items are covered and what will void them. Many companies offer one year or two years of coverage; however, there is no industry standard.

Metal roof systems for steep-slope applications


Click on a topic for more information. Metal roof systems description

There are three general categories of metal roof systems used for steep-slope roofing applications: architectural metal panel, structural metal panel and metal shingle/shingle panels. Generally, architectural metal panel roof systems are watershedding and are intended for use on steep slope roofs. Structural metal panel roof systems are used on low and steep slope roofs. Structural metal panel roof systems can be used on low slope roofs because of their hydrostatic, or water barrier, characteristics.

Because architectural metal panel roof systems typically are designed to be used on steep slopes that will shed water rapidly over the metal panels' surface, the seams typically are not watertight. Many architectural metal roof systems are well suited for use on roof slopes of 3 inches per foot (14 degrees) or greater. One exception to the general slope guidelines for architectural metal panel roof systems is the traditional flat seamed, soldered or welded metal roof system, such as copper. It may be specified on slopes less than 3 inches per foot (14 degrees). Solid roof sheathing, or decking, is required for architectural metal panel roof systems, and the National Roofing Contractors Association recommends using underlayment.


Example of an architectural metal panel roof system

Most structural metal panel roof systems are designed to resist the passage of water at laps and other joints, as sealant or anti capillary designs can be used in the seams. Structural metal panel roof systems possess strength characteristics that allow them to span supporting members.


Example of a structural metal panel roof system

Metal shingles and shingle panels are available in numerous varieties for use as steep-slope roof coverings. Most of the metal shingles are press-formed during the manufacturing process to provide a variety of shapes. These products can take the shape of individual or multiple asphalt, tile, slate or wood shingle configurations.

Seam types

There are many categories of metal panels. The term standing seam often is used as a generic description for a class of metal roof seams. The name standing seam is derived from the fact that the seams are joined together above the panel flats. The term also is used to refer to a panel profile that includes a standing seam: the vertical leg/flat pan and the trapezoidal seam. The trapezoidal standing seam is more commonly associated with structural metal panels. Other panel types are batten, flat, bermuda and shingled.

The original batten seam consisted of vertical leg panels placed between wood batten strips and covered with a cap. Today, many batten seam panels are constructed entirely of metal. Because they are designed to shed water, batten seam panels primarily are used in architectural applications.


Example of standing seam profiles

A flat seam is created with individual panels applied in a shingled application. One panel edge is folded back on top of itself; the other panel is folded under, and the two panels are hooked together. Again, because flat panels are considered watershedding, they are more commonly found in architectural installations. Some flat seam panel systems, such as copper, are commonly soldered, which allow them to perform on less steep slopes.


Example of a flat seam

Roof deck

Architectural metal panel roof systems and structural metal panel roof systems are installed over a large variety of substrates. There are two general categories of substrates: continuous or closely spaced decking that provides solid support for the metal roof panel, and the other is composed of spaced structural supports (such as purlins) where the metal panels must span between supports. Most structural metal panels are used over spaced structural supports without being supported by a solid roof deck.

Metal shingles and metal shingle panels should be installed over continuous or closely spaced wood decking, furring strips, or metal or wood purlins using a batten or counter-batten system. These roof coverings typically are considered to be watershedding roof systems, so the roof slope should be 3:12 (14 degrees) or greater.

Underlayment

Underlayment (or "felt paper" as it is frequently called) is installed over the roof deck before the application of a metal roof system. An underlayment performs two primary functions: it provides temporary weather protection until the metal roof system is installed, and it provides a secondary weatherproofing barrier if moisture infiltrates the metal roof panels.

Asphalt saturated, nonperforated organic felts are among the most common underlayments; they commonly are designated as Type 15 and Type 30 or referred to as No. 15 and No. 30, which are reflective of a once used pound per square weight designation. The terms Type I and Type II now are used within the industry in lieu of No. 15 or No. 30, respectively.

For metal panel roof systems, metal shingles and metal shingle panels, the National Roofing Contractors Association recommends a minimum of one layer of No. 30 asphalt-saturated felt applied horizontally in shingle fashion on roof decks having a slope of 4:12 (18 degrees) or more. For roof decks having slopes of 3:12 (14 degrees) up to 4:12 (18 degrees), a minimum of two layers of No. 30 asphalt-saturated underlayment should be applied horizontally in shingle fashion.

Underlayments typically are not used with structural metal panel roof systems when intermittent supports are used to carry the roof systems. However, if there is a continuous or closely spaced roof deck, the National Roofing Contractors Association recommends an underlayment be installed.

In locations where the average temperature for January is 30º F or less, the National Roofing Contractors Association suggests installation of an ice-dam protection membrane. An ice-dam protection membrane generally is a self-adhering polymer-modified bitumen membrane.

An ice dam protection membrane should be applied starting at a roof's eaves and extending upslope a minimum of 24 inches from the exterior wall line of a building. For slopes less than 4:12 (18 degrees), a minimum of 36 inches is recommended. See Figure 1.


Figure 1 - Example of ice damming

the National Roofing Contractors Association also recommends a slip sheet be installed over the underlayment for metal panel roof systems. A slip sheet is a layer of smooth building paper, such as rosin-sized or unsaturated building paper. Its purpose is to protect the underlayment from damage, as the panels can adhere to and tear the underlayment.

Vapor retarders, insulation and ventilation

Condensation should be expected to develop on the undersides of metal roof panels. Careful consideration should be paid to vapor retarder, insulation and ventilation issues. Because every building is in some way unique, building owners and designers may need to consult moisture-control specialists.

Material standards

the National Roofing Contractors Association does not make any recommendations about which product or manufacturer to use; however, the National Roofing Contractors Association does recommend that metal panel roof systems meet standards established by the American Society for Testing and Materials (ASTM). Warranties

When purchasing a new roof system, there will be two warranties to consider. First, there will be the manufacturer's warranty. In general, these warranties cover defects in the manufacture of the roof covering. In the case of metal roof systems, manufacturers tend to cover only the metal finishes or coatings. Please read the National Roofing Contractors Association's consumer advisory bulletin addressing roofing warranties for more information. Once the project is complete, be sure the contractor provides you with a certificate for your records.

Second, the roofing contractor will provide you with a warranty covering his workmanship. Typically, this will cover installation and related issues. The warranty should contain what items are covered and what will void them. Many contractors offer one year or two years of coverage; however, there is no industry standard.

Slate


Click on a topic for more information. Material description

Roofing slate is a dense, durable, naturally occurring material that is essentially nonabsorbent. Two properties of slate are cleavage and fracture. It has natural cleavage, which permits it to be easily split in one direction. Fracture, usually occurring at right angles to the cleavage, is called the grain. Roofing slate commonly is split so the length of the slate runs in the direction of the grain. The surface texture of slate after being split for commercial use derives from the characteristics of the rock from which it was quarried. Some slate splits to a smooth, practically even surface, while other yields a surface that is rough and uneven.

The color of slate is determined by its chemical and mineral composition. Because these factors differ in various regions, roofing slate can be obtained in a variety of colors. In addition, exposure to weather causes slate to change color. The degree of change varies depending on the slate. Slate exhibiting minimal color change is known as "permanent" or "unfading" slate. Slate that shows a more marked color change is known as "weathering" slate. Between unfading slate and weathering is "semi weathering" slate.


Example of a slate roof system

There are several classifications for slate roof systems. The first is standard slate, which refers to slate that generally is from 3/16 inch (5 mm) to 1/4 inch (6 mm) thick with uniform length. The category "standard smooth" refers to standard slate that has a relatively smooth surface, in comparison with "standard rough" or just "rough". Rough slate has a rougher texture and generally is available in thicker pieces. Finally, there is "graduated/textural slate," which is designed with varying lengths and thicknesses and generally is rougher than standard slates.

Roof deck

the National Roofing Contractors Association recommends slate be applied over continuous or closely spaced wood decking. When plywood is used, the National Roofing Contractors Association recommends the use of a minimum 5/8 thick nominal exterior-grade plywood.

Caution should be exercised when roof decks are constructed out of the following materials: Underlayment

Underlayment (or "felt paper" as it is frequently called) is installed over the roof deck before the application of slate. An underlayment performs two primary functions: it provides temporary weather protection until the slate is installed, and it provides a secondary weatherproofing barrier if moisture infiltrates the slate roof covering. Many slate roofs have outlived the underlayment felts over which they were installed. Therefore, an underlayment's service life should be comparable to the design service life of the slate roof covering.

Asphalt saturated, nonperforated organic felts are among the most common underlayments; they commonly are designated as Type 15 and Type 30 or referred to as No. 15 and No. 30, which are reflective of a once used pound per square weight designation. The terms Type I and Type II now are used within the industry in lieu of No. 15 or No. 30, respectively.

Another type of underlayment is a synthetic underlayment. It is characterized as being lightweight, water-resistant and less likely to wrinkle; having high tear strength; and being easy to walk on—even when wet. Theoretically, the product may be left exposed to the elements for extended periods of time. Although synthetic underlayments and their purported attributes seem appealing, there are significant issues to consider before using them. To date, there are no applicable ASTM standards for these products. Many synthetic underlayments do not meet current building code requirements, so manufacturers need to obtain a code evaluation report for code compliance.

the National Roofing Contractors Association recommends a minimum of one layer of No. 30 asphalt-saturated felt applied horizontally in shingle fashion on roof decks having a slope of 8:12 (34 degrees) or more. Where weather conditions are severe and hard wind-driven rains are common, the National Roofing Contractors Association recommends a minimum of two layers of No. 30 asphalt-saturated felt applied horizontally in shingle fashion. For roof slopes of 4:12 (18 degrees) to 8:12 (34 degrees), a minimum of two layers of No. 30 asphalt-saturated felt are recommended as long as standard-size slate with 3-inch minimum headlap is used. the National Roofing Contractors Association does not recommend installing slate roof systems on roof slopes less than 4:12 (18 degrees).

In locations where the average temperature for January is 30º F or less, the National Roofing Contractors Association suggests installation of an ice-dam protection membrane. An ice-dam protection membrane generally is a self-adhering polymer-modified bitumen membrane.

An ice dam protection membrane should be applied starting at a roof's eaves and extending upslope a minimum of 24 inches from the exterior wall line of a building. For slopes less than 4:12 (18 degrees), a minimum of 36 inches is recommended. See Figure 1.


Figure 1 - Example of ice damming

Fasteners

the National Roofing Contractors Association suggests the use of copper slating nails for slate. the National Roofing Contractors Association does not recommend unprotected black-iron and electroplated nails. the National Roofing Contractors Association recommends nails for standard-sized slate are sharp-point, 3/8 inch large flat head, copper-wire slating nails. Nails should be long enough to penetrate through all layers of roofing materials and extend through the underside of the roof deck or penetrate at least ¾ inch into wood plank or board decks. All roofing slate should have a minimum of two nails, however, slate subject to high-wind conditions and/or thicker slate should be fastened with four nails.

Flashings

Flashings for slate roofs fall into four categories: perimeter edge metal, penetrations, valleys and vertical surfaces. See Figure 2.
Figure 2 - Basic sheet metal flashing components

Apron, step and cricket flashings require some form of counterflashing to cover and protect the top edges from water intrusion. In many cases, the wall covering or cladding material acts as counterflashing. When this does not occur, a metal counterflashing mounted to the vertical surface should be installed. See Figures 3, 4 and 5 for examples.


Figure 3 - Example of through-wall metal counterflashing inset in masonry mortar joint


Figure 4 - Example of metal counterflashing embedded in masonry mortar joint


Figure 5 - Example of surface-mount metal counterflashing

Material standards

the National Roofing Contractors Association does not make any recommendations about which slate or manufacturer to use; however, the National Roofing Contractors Association does recommend that slate meet standards established by the American Society for Testing and Materials (ASTM). Warranties

When purchasing a new roof system, there will be two warranties to consider. First, there will be the manufacturer's warranty. In general, these warranties cover defects in the manufacture of the roof covering or in the case of slate, failure in the slate itself. Please read the National Roofing Contractors Association's consumer advisory bulletin addressing roofing warranties for more information. Once the project is complete, be sure the contractor provides you with a certificate for your records.

Second, the roofing contractor will provide you with a warranty covering his workmanship. Typically, this will cover installation and related issues. The warranty should contain what items are covered and what will void them. Many contractors offer one year or two years of coverage; however, there is no industry standard.

Wood shakes and wood shingles


Click on a topic for more information. Material description

Wood shakes and wood shingles are manufactured from western red cedar, cypress, pine and redwood trees. Shakes are split from logs and reshaped by manufacturers for commercial use. They are thicker at the butt end than shingles; generally one or both surfaces are split to obtain a textured effect. A split and resawn shake has a split face and sawn back. A taper sawn shake has a natural taper and is sawn on both sides. Wood shingles are sawn on both sides and have an even taper and uniform thickness. When applied to shingles, the industry terms "Perfection" and "Royal" mean 18 inch and 24 inch lengths, respectively.

Cedar shakes and cedar shingles are available pressure treated with fire retardants and chemical preservatives for increased fire resistance and to prevent premature rot and decay in some climates.

Pine shakes are made from southern yellow pine and are taper sawn. They also are available pressure treated with preservatives to protect against decay and insects. Interlayment felts are required for pine shakes.

Roof deck

Wood roof systems may be applied over continuously or closely spaced wood decking or over a spaced, sometimes referred to as "skipped," sheathing. Solid roof decking or sheathing should be used in areas of the roof deck where an ice dam protection membrane is required.

The most common materials used for roof decks are plywood or oriented strand board (OSB). When plywood is used, the National Roofing Contractors Association recommends the use of a minimum 15/32 thick or ½ inch nominal exterior-grade plywood for 16-inch rafter spacings and 5/8 inch nominal thickness for 24-inch rafter spacings. For OSB, the National Roofing Contractors Association recommends a minimum 15/32 inch thick or ½ inch nominal exterior-grade OSB for 16-inch rafter spacings.

Caution should be exercised when roof decks are constructed out of the following materials: Underlayment and interlayment

Asphalt saturated, nonperforated organic felts are among the most common underlayments used for wood shakes and wood shingles; they commonly are designated as Type 15 and Type 30 or referred to as No. 15 and No. 30, which are reflective of a once used pound per square weight designation. The terms Type I and Type II now are used within the industry in lieu of No. 15 or No. 30, respectively.

When underlayment (or "felt paper" as it is frequently called) is specified, No. 15 or No. 30 asphalt-saturated, nonperforated felt should be applied shingle fashion on roof decks having a slope of 4:12 (18 degrees) or more. the National Roofing Contractors Association does not recommend using wood shakes and wood shingles on slopes less than 4:12 (18 degrees).

In the case of wood shakes, these sheets are produced in 18 inch (450 mm) widths as "interlayment" felts; that is, they are applied between courses of wood shakes rather than directly over a substrate. See Figure 1.


Figure 1 - Example of a wood shake roof system with underlayment and interlayment

In locations where the average temperature for January is 30º F or less, the National Roofing Contractors Association suggests installation of an ice-dam protection membrane. An ice-dam protection membrane generally is a self-adhering polymer-modified bitumen membrane.

An ice dam protection membrane should be applied starting at a roof's eaves and extending upslope a minimum of 24 inches from the exterior wall line of a building. For slopes less than 4:12 (18 degrees), the National Roofing Contractors Association recommends a minimum of 36 inches. See Figure 2.


Figure 2 - Example of ice damming

Fasteners

Wood roofing may be attached to a roof deck with noncorroding, galvanized steel or stainless steel nails or noncorroding metal staples. A minimum of two fasteners should be used to attach each shake or shingle. Nails should be long enough to penetrate through all layers of roofing materials and extend through the underside of the roof deck or penetrate at least ¾ inch into wood plank or board decks.

Flashings

Flashings for wood roof systems fall into four categories: perimeter edge metal, penetrations, valleys and vertical surfaces. Apron, step and cricket flashings require some form of counterflashing to cover and protect the top edges from water intrusion. In many cases, the wall covering or cladding material acts as counterflashing. When this does not occur, a metal counterflashing mounted to the vertical surface should be installed. See Figures 3, 4 and 5 for examples.


Figure 3 - Example of through-wall metal counterflashing inset in masonry mortar joint


Figure 4 - Example of through-wall metal counterflashing embedded in masonry mortar joint


Figure 5 - Example of surface-mount metal counterflashing

Material standards

the National Roofing Contractors Association does not make any recommendations about which shake or shingle products or manufacturers to use. There are no ASTM standards for wood roof coverings; however there are standards for grading. Cedar Shake and Shingle Bureau (CSSB) Standard CSSB-97 contains grading rules for wood shakes and wood shingles. the National Roofing Contractors Association recommends that cedar shakes and cedar shingles be a minimum No. 1 grade, which requires 100 percent edge grain, clear heartwood and no face defects.

Warranties

When purchasing a new roof system, there will be two warranties to consider. First, there will be the manufacturer's warranty. In general, these warranties cover failures in the roof covering product. Please read the National Roofing Contractors Association's consumer advisory bulletin addressing roofing warranties for more information. Once the project is complete, be sure the contractor provides you with a certificate for your records.

Second, the roofing contractor will provide you with a warranty covering his workmanship. Typically, this will cover installation and related issues. The warranty should contain what items are covered and what will void them. Many contractors offer one year or two years of coverage; however, there is no industry standard.

Synthetic


Click on a topic for more information.
"Synthetic" as it pertains to steep-slope roofing materials refers to manufactured products that replicate asphalt shingles, concrete tile, clay tile, metal panels, slate, wood shakes and wood shingles. Synthetic roof coverings contain recycled plastic and/or rubber as a key ingredient. These products have been available since 1993.

There are some advantages to using synthetic roof coverings when compared to their traditional counterparts. Synthetic slate, or "fake slate," for example, weighs substantially less than natural slate. The reduction in weight allows synthetic slate to be installed over conventional roof decks. Some synthetic products purport to be hail-, mold- and algae-resistant. Several synthetic cedar shake and cedar shingle manufacturers claim a labor savings, because fire-retardants or anti-algae coatings do not have to be applied to the product.

Despite the benefits, there are some significant drawbacks. Synthetic roof coverings are relatively new and there isn't a proven track record about their performance. Most synthetic products are manufactured with dyes or coloring agents and it is unknown whether these products will fade because of ultra-violet exposure and weathering. It also is unknown whether these products will become more brittle or less flexible over time. And most important, model building codes do not recognize any synthetic roof coverings. You need to check with your local building department before installing these products. Because of these reasons, caution should be exercised when using synthetic roof covering products.

Material standards

Currently, there are no American Society for Testing and Materials (ASTM) standards for synthetic roof covering products.

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American Society of Civil Engineers - Member
Email: mattstiefel@berthowe.com
 
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Joseph Santa Cruz Joseph Santa Cruz
Professional Engineering License, Civil Engineering
Bachelor of Science, Architectural Engineering, California Polytechnic State University, San Luis Obispo
Email: jospehsantacruz@berthowe.com
 
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Stephen Hodgeson STEPHEN HODGESON
B.S., Mechanical Engineering, University of Utah
Professional Engineer Texas
Professional Engineer California
Professional Engineer Colorado
Professional Engineer Idaho
Professional Engineer Indiana
Mechanical Engineer Texas
Fire Protection Engineer Texas
Email: shodgeson@berthowe.com
 
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Vitaly Feygin VITALY FEYGIN
M.S. Structural Engineering, Kharkow Academy of Transportation
Licensed Professional Engineer, Maryland
Licensed Professional Engineer, Florida
Licensed Professional Engineer, Pennsylvania
Publications: Sea Wall Systems (STRUCTURE Magazine, December 2009)
Rational Approach to Design and Analysis of Piers and Marginal Wharves (STRUCTURE Magazine, slated for July 2010)
US and International Patents: Diaphragm Sea/Retaining Wall (Patent Pending)
Universal Feygin’s Cofferdam System (Patent Pending)
Awards: 2008 ACI Grand Prize for Excellence in Concrete Design and Construction for Harrah’s Chester Casino and Racetrack Bridge
2008 ACI Grand Prize Award for Excellence in Concrete Design and Construction for Ritz Carlton Water Front Development, Baltimore, Inner Harbor
2008 Facilities Engineering Award Winner-American Association of Port Authorities
Email: vitalyf@berthowe.com
 
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The following roofing terms have been defined for you in BHApedia, our online illustrated dictionary of construction terminology.

Building paper Built up roof California roof Confined Rake Counterflashing Curtain wall Diato flashing Dormer vent Drip edge Eave vent Field tile Flat roof Gable Gable roof Gable truss Gable vent Head flashing Headlap Hip roof Mansard roof Mineral-surfaced roofing Modified bitumen Neoprene roof Parapet Rafter Rafter tail Rake Rake wall Ridge blocking Ridge board Ridge vent Roof drain Roof felt Roof jack Roof sheathing Roof slope Roof tile Splash block Valley Valley flashing Vent cap Vent flashing Vent stack