This section deals with roof covering materials such as shingles, tile, roof panels, and membranes. In selecting material for roof covering, take into account its weight (heavier material requires larger support members) and heat-holding qualities (does it heat up and stay hot into the night?), color (in our hot climate, a white material will reflect most of the heat away from the building), as well as cost, fire rating, maintainability, installation characteristics, and its durability (how well can it tolerate high and low temperatures and for how long?). Of all the building components, roofing materials receive the most direct exposure to the elements. Least-costly roof materials typically offer the least durability. Making a sustainable choice in roofing will probably cost more initially but will prevent frequent replacement costs and frequent trips to the landfill.

Also see the Green Building Factsheets for introductions to this and other green building topics.

When considering a roof, keeping the weather out is the priority. In Green Building several additional issues must be considered, such as:

• Appropriateness for rainwater collection and photovoltaic equipment;
• Minimization of material consumption, i.e., how long will it last? Does it require more structure, layers, or insulation?

The following describes product considerations in further detail.

Slate, clay, and cementitious roof materials offer excellent durability but are heavy. Fiber-cement composite roof materials are somewhat lighter and use fiber materials resourcefully. Some use waste paper as well as wood fiber. Many have 60-year warranties.

Metal roof materials (steel, copper and aluminum) contain high percentages of recycled content, up to 100 percent in many aluminum products. Metal may be easily coated with a white reflective coating and is lightweight and durable. An additional advantage is that these materials are easily recycled in their post-use.

Asphalt shingles contain recycled, mixed paper in their base and some installations use reclaimed minerals in the surface aggregate. This type of material does not last as long as the others mentioned above. And, this material does not block heat from the building.

Recycled plastic roof materials have been introduced as a lightweight, environmental and durable option.

White membrane roofs offer a high degree of solar heat reflectance and are fabricated from strong, flexible waterproof materials.

Asphalt shingles

Certain asphalt or composition shingles contain recycled, mixed paper in their base, and some installations use reclaimed minerals in the surface aggregate. This type of roofing material does not last as long as others mentioned in this section, and it is not recyclable, taking up landfill space. More frequent replacement makes them cost more over the life of the building, both financially and environmentally. Light-colored composition shingles provide much less heat reflectance than other light colored roofing materials because the base to which the light colored granules is applied is black, causing heat absorption.

Recycled rubber roofing

Recycled rubber roofing is beginning to be manufactured. This product does not have a long track record, but it should prove quite durable, and puts recycled tires to good use. For those interested in capturing rainwater from roofs for drinking purposes, it is not known at this time if there is a taste or purity impact from using rubber roof material.

Metal roof materials

Steel and aluminum can contain high percentages of recycled content, up to 100 percent in some aluminum products. In addition to being lightweight and durable, these materials are easily recycled. All metal roofing is energy-intensive to produce, but additional advantages are that they reflect heat (reducing the energy needs for hot summers), and metal is a good surface for rainwater catchment.

Metal coatings

Zinc (galvanized) coatings oxidize to protect the steel. Protection is lost when the oxidation process uses up the zinc, and the steel underneath can rust. On low-sloped roofs in wet climates, coating loss and rust can show up in as little as five years.

Aluminum coatings are superior to zinc, carrying warranties up to 20 years. They are inert, and do not degrade over time.

Aluminum-zinc alloys, or Galvalume, will outperform aluminized coatings and exceed 20 warrantees.

Paint

Only use factory-applied paint. Polyester resin finishes offer least durability. Fading will occur in 5 to 7 years.

Silicone-modified polyester finishes are superior (the more silicone, the better the performance). Twenty-year warranties are available.

Fluoropolymer resins provide a state of the art finish. Seven paint companies produce this paint under the brand names of Kynar, Hylar, Duranar, Nubelar, Fluropon, Trinar, and Visulure.

Bare aluminized or Galvalume panel can last 40 years without maintenance and is a better choice than polyester resin finishes.

Panel thermal movement

Metal panels respond to temperature change by expanding and contracting. This can cause the fastener hole size to increase, resulting in leaks. Newer fasteners have rubber washers that can withstand heat and UV rays and cover holes.

Dark colors will experience the largest thermal movement. (And cost more in air conditioning bills.)

Panels installed over purlins will not harm the roof system with thermal movement.

If installing over a solid deck, use Z-shaped metal sleepers over the decking. The sleepers will move with the panels and eliminate fatigue where the screws penetrate the panels (the screw hole will become elongated causing leaks) or the screws will lose grip on the decking.

Solid aluminum panels have a higher coefficient of expansion than steel and will strain fasteners with the increased movement from temperature change.

Galvanic reactions

Protect metal panels on the anodic end of the galvanic scale from fasteners and flashings on the cathodic end to prevent corrosion (see Fig. 1).

Fig. 1: Galvanic Scale

Material Choices for Sloped Roofs

Slate shingles are durable, attractive, environmentally benign, and can be easily recycled. On the negative side, slate's costs are high because it is not naturally found in Texas, and it has heat-absorbing characteristics because of its dark color.

Clay tiles are made by the shaping and firing of clay. The quality of the tile depends on the quality of the clay. The lower-end tiles are susceptible to freeze-thaw damage, meaning that the clay's expansion and contraction from large temperature changes can cause deterioration. Locally produced clay tiles are available, but imported tiles are also readily accessible. Inquire about production location, favoring the shortest distances, which will also be more favorable to the local economy and lower transportation costs. Clay tiles are a good choice for rainwater collection. White glazed clay tiles have an additional contribution to reflecting heat from the building.

Concrete tiles offer excellent durability but are heavy and require stronger structure. They are a cost-effective alternative to clay but retain heat longer. Environmentally, concrete tile is more energy-intensive to produce.

Fiber-cement composite slates and shakes are long lasting, typically having 60-year warranties, and are fireproof. They are somewhat lighter than concrete tiles and use fiber materials, waste paper and wood fiber, resourcefully. However, they are not commonly found in light colors, so they absorb heat. Certain brands may not serve well in climates with severe temperature variations, but this has not been an issue for the central Texas area.

Material choices for "Low-slope" Roofs

Choices for low-slope roofing, often referred to as flat roofing, consist of built-up roofing, modified bitumen, single-Ply membranes, and low-slope metal. Conventional low-slope roofing absorbs a lot of sunlight. Preference should be given to roofs with a high reflectivity and a low emissivity measured through the solar reflectance index (SRI). The Green Building Program recommends selection of roofing materials with a SRI of 90 or higher.

Built-up Bituminous Roofing

Look for manufacturers who use recovered material in their product or who process post-consumer roofing material into other products. Give preference to coal tar BUR as opposed to asphalt BUR because of its added durability. With insulated roof assemblies, BUR is generally adhered to the insulation. During re-roofing, both insulation and BUR membrane are typically landfilled.

Modified Bitumen

The low life expectancy of 15 years and the difficulty in recycling of modified bituminous roofing create great waste problems and make it a poor choice from a life-cycle perspective.

Give preference to heat welding to adhere membranes instead of hot asphalt or cold adhesives. If adhesive is necessary for modified bituminous roofing, choose adhesive products that are water-based and/or are low-VOC. Give preference to reinforcing carriers of amorphous polypropylene (APP) over styrene butadiene styrene (SBS) and polyalphaolefin (PAO).

Avoid the use of bituminous roofing applied with cold adhesive. Cold adhesives are volatile chemicals that also pose health and safety risks. They are combustible, harmful or fatal if swallowed, and dangerous to inhale or be exposed to for any length of time. Some ingredients latent within cold adhesives are certifiably "toxic" and must be disposed of in unconventional ways. Furthermore, use of cold adhesives also requires the use of volatile solvents and other chemicals for installation.

Single-Ply Membranes

Single-ply membranes consist of ethylene propylene diene monomer (EPDM), polyvinyl chloride (PVC), polyolefin, and chlorosulfonated polyethylene (CSPE or Hypalon).

EPDM Membranes

EPDM is a type of synthetic rubber that is thermoset. As with other thermoset plastics, EPDM is not recyclable into new membrane. When designing a single-ply elastomeric roofing system, such as EPDM, consider mechanical fastening in high-wind areas or ballasting in low-wind areas, unless the roof design is so complex that a fully adhered system is the only practical solution. If full adhesion of the roofing membrane is necessary, choose adhesive products that are low-VOC (<250 g/l if possible, or if not, <400 g/l). If using a solvent-based adhesive is necessary to anchor an EPDM roof, all air intakes near the work area should be shut to prevent solvent fumes from entering the building. Choose light-colored coatings on EPDM roofing in all cases where the building has a net cooling load to reduce heat gain. Look for elastomeric membrane roofing containing recovered content.

PVC Membranes

PVC is a thermoplastic, making it fully weldable both during installation and for any necessary repairs. Flexibility is provided by adding plasticizers to the membrane. Loss of the membrane's plasticizers can result in premature failure. Some of the strongest opposition to PVC roofing comes from those concerned about fire.

Polyolefin Membranes

Due in part to environmental and health concerns about PVC, a number of manufacturers have begun producing non-chlorine-based, thermoplastic roofing membranes. Generally, this type of membrane is referred to as flexible polyolefin (FPO) or thermoplastic olefin (TPO). When using polyolefinated materials, consider a ballasted application that will protect the roofing membrane from UV degradation. Choose light-colored thermoplastic roofing in all cases where the building has a net cooling load to reduce heat gain.

CSPE or Hypalon Membranes

Chlorosulfonated polyethylene, more commonly known by the tradename Hypalon, is a white polymer that is often marketed for its energy-saving reflectivity. When Hypalon is installed, it goes down as an uncured elastomer. Upon exposure to heat and moisture, the plastic converts into a fully cured thermoset elastomer. Hypalon has excellent weather resistance, even in the typical high-reflectivity white. Some environmental concern does exist over the chlorine in the plastic.

Low-Slope Metal Roofing

Some manufacturers of metal roofing now offer low-slope systems that work with pitches as low as 2% (1/4" in one foot). To remain watertight at this low pitch, the standing seam for the roofing has to be specially designed to prevent water penetration.

See "Building Construction Consultants" and "Roofing Services Consultants" in Yellow Pages.

See "Roofing Contractors", "Roofing Equipment and Supplies", and "Roofing Materials" in Yellow Pages.

ATAS International
6612 Snowdrift Rd.
Allentown, PA 18106
(800) 468-1441
419 E. Juanita Ave.
Mesa, AZ 85204
(800) 879-8382
www.atas.com
Steel and Aluminum shingles, 35-60 lbs. per sq. for aluminum, 80-140 lbs per sq. for steel, Class A rating, 25 yr. warranty, the look of shake, slate, or tile, (4) Kynar 500 colors
Local Dealer: Spec Building Materials, Inc.: (512) 836-1531

American Building Components
Lubbock, TX
(888) 800-5387
Concealed fastener roofing panels

Bethlehem Steel Corp.
1170 Eighth Ave.
Bethlehem, PA 18016-7699
(800) 352-5700 ext. 400
Prepainted white galvalume

Celadon Ceramic Slate
11519 US Route 250 North
Milan, OH 43705
(800) 699-9988
www.celadonslate.com
Ceramic slate
Local: JEH/Eagle Supply, (512) 219-6266

Central Texas Metal Roofing Supply, Inc.
Austin and Buda
(800) 428-7412
Manufacturer and distributor of custom and standard commercial/residential metal roofing

Classic Products, Inc.
8510 Industry Park Dr. P. O. Box 701
Piqua, OH 45356
(800) 543-8938
www.classicroof.com
Rustic Shingle recycled aluminum shingles resemble wood shakes. 98% postconsumer recycled content, lifetime limited warranty, KYNAR finish approved for drinking water catchment

Crowe Building Products Ltd.
116 Burris St.
Hamilton, Ontario, Canada L8M2J5
(905) 529-6818
www.authentic-roof.com
"Authentic Roof" has slate look made from 100% recycled and re-engineered polyethylene, polypropylene and EPDM rubber. 206 lbs/sq, 50 yr warranty, 3 edge profiles, 5 colors, Class C fire rating

Custom Bilt Metals
9845 Joe Vargas Way
So. El Monte, CA 91733
(800) 826-7813
www.custombiltmetals.com
Metal tile, standing seam, and snap lock panels

D'Hanis Brick and Tile Co.
11931 Radium
San Antonio, TX 78216-2714
(800) 299-9399
www.dhanisbricktile.com
Clay tile
Local: Brick and Tile Center: (512) 834-8525

Di Bendetto Tile Co., Inc.
515 Southwest Blvd.
Kansas City, MO 64108
(800) 338-2088
"Elagante" Tile, concrete tile with EPS undercarriage creates a lighter tile system with insulation value of R-4.5
Master dealer: Mid America Supply
P.O. Box 7772
Amarillo, TX 79114
Local: Tileworks of Texas, Mark Slowley, (512) 835-8453

Drexel Metals Corporation
204 Railroad Dr.
Ivyland, PA 18974
(888) 321-9630
www.drexmet.com
Manufacturer of "Cedar Ridge" metal shake panels

Dura-Loc
P.O. Box 220
Courtland, Ontario
Canada NOJ 1E0
(800) 265-9357
www.duraloc.com
Metal panels with look of shake, tile, and slate

Eagle Roofing Products
3546 North Riverside Ave.
Rialto, CA 92377
(800) 300-3245
www.eagleroofing.com
Standard weight and lightweight concrete roofing tiles
Local Dealers:
ABC Supply, (512) 454-0040
Austin Roofer's Supply, (512) 834-4347

EcoStar
104 Terrace Drive
Mundelein, IL 60060
(800) 877-6956
www.premiumroofs.com
"Majestic Slate" 100% recycled plastic slate shingles, 216 lbs/sq, 50 yr warranty, 9 colors, Class C fire rating
Local Dealer: JEH Supply: (512) 219-6226

Englert Inc.
R.R. #1 Thornton
Ontario Canada, L0L 2N0
(705) 436-1723
1200 Amboy Ave.
Perth Amboy, NJ 08862
(732) 826-8614
www.englertinc.com
Manufacturer of commercial/residential metal shingles and standing seam panels

Galvamet Inc.
400 North Sam Houston Pkwy. East, Ste. 208
Houston, TX 77060
(888) 489-1637
www.galvamet.com
"Galvatile" stone-coated, metal roofing panels

Gerard Roofing Technologies
955 Columbia St.
Brea, CA 32821-2923
(Also has a new plant in Mesquite, TX)
800-23-ROOFS
www.gerardusa.com
Galvalume or pre-painted galvanized roofing tiles and shakes coated with graded stone granules, 140 pounds per square, Class A rating, 40 year warranty

Gladding, McBean
www.gladdingmcbean.com
Clay tile
Local: Elgin Butler Brick: (512) 453-7366

Ludowici Roof Tile, Inc.
P.O. Box 69
New Lexington, OH 43764
(800) 945-8453
www.ludowici.com
Premium clay tile
Local Retailer: JEH Eagle Supply: (512) 219-6226

Maxitile, Inc.
17141 S. Kingview Ave.
Carson, CA 90746
(800) 338-8453
www.maxibuildingproducts.com
Fiber-cement tile, 340 pounds per square, Class A rating, 50 year warranty,' mission' tile look
Local Dealers:
JEH/Eagle Supply, (512) 219-6226
Austin Roofers Supply, (512) 834-4347
Spec Building Materials, (512) 836-1531

Metal Sales Manufacturing Corp.
3838 North General Bruce Dr.
Temple, TX 76501
(800) 543-4415
www.mtlsales.com
Stile® metal tile, 100 pounds per square, Class A rating, 20 year limited warranty, Simulated clay tile appearance
Local: Central Texas Metal Roofing: (512) 452-1515

MetalWorks
1005 Beaver Grade Rd.
Moon Township, PA 15108-2944
(800) 320-0101
www.metalworksroof.com
Aston Wood Steel shingles, 63 pounds per square, 5 Kynar 500 colors available, simulates wood shake appearance
Local Distributor: Spec Building Materials, Inc.: (512) 836-1531

MonierLifetile
(800) 571-8453
www.monierlifetile.com
CedarLite® , DuraLite® and DeckLite® lightweight tile simulates wood shingles and shakes, Class A rating, limited lifetime warranty
Local: Hanson Roof Tile: (512) 845-7314

Montopolis Supply Co.
255 Bastrop Hwy.
Austin, TX 78741
(512) 385-3270
Metal roofing supplier

Perma Tile Roofing Inc.
60 Don Westbrook Ave. N.
Jasper, GA 30143
(800) 701-2982
Color coated metal tile system

Re-New Wood, Inc.
P.O. Box 1093
Wagoner, OK 74467
(800) 420-7576
www.ecoshake.com
Eco-Shake® 100% recycled vinyl/wood shingle, 250 lbs/sq, 50 yr warranty, 4 colors, Class A fire rating
Local Distributor: Polston Sales & Marketing: (972) 258-6255

Scandinavian Profiling Systems
5449 Maule Way
Mangonia Park, FL 33407
(800) 248-6955
www.nordmantile.com
"Nordman Tile" metal panel systems with the look of European tile

Simulated Metal Roofs
P. O. Box 454
Portmouth, NH 03802-0454
(888) 578-7663
Sim-TileÆRapide complete metal roofing system looks like tile

Steel Tile Co.
R.R. #1 Thornton
Ontario Canada, L0L 2N0
(705) 436-1723
www.steeltile.com
Manufacturer of commercial/residential metal roofing panels

Tasman Roofing Inc.
827 Ave. H East #211
Arlington, TX 76011
(800) 258-9740
www.decraroofing.com
"Decra" stone chip coated steel panels, tile and shake patterns

TuffVENT (attic rafter vents)
EHV-Weidmann Industries, Inc
One Gordon Mills Way
St. Johnsbury, Vermont 05819-0903
(802) 748-8106
www.weidmann-industrial.com

UStile
909 West Railroad St.
Corona, CA 91720
(909) 737-0200
www.ustile.com
"ClayMax," "Claylite," and "ProShake" ceramic and clay tile
Local:
ABC Supply, (512) 454-0400
Austin Roofer's Supply, (512) 834-4347

Vail Metal Systems
P.O. Box 230
Edwards, CO 81632
(888) 245-6385
www.vailmetal.com
Copper and Kynar 500 galvalume panels

Vincent Metal Goods
P.O. Box 360
Minneapolis, MN 55440
(800) 328-7800
www.vincentmetalgoods.com
"ColorKlad" and "AlumaKlad" standing seam metal roofing panels

Welsh Mountain Slate Inc.
249 Bridge St. West
Campbellford, Ontario, Canada, K0L 1L0
(800) 865-8784
www.welshmountainslate.com
Welsh Mountain Slate™; 100% post industrial recycled car tires and polypropylene shingle, 189 lbs/sq, 50 yr warranty, 4 colors, Class C fire rating

Membrane Roofing Materials

Carlisle Syntec Systems
PO Box 7000
Carlisle, PA 17013-0925
(800) 233-0551
EDPM

Conklin Company Inc
551 Valley Park Dr.
P.O. Box 155
Shakopee, MN 55379
(800) 888-8838
Hypalon

Duro-Last Inc
525 Morley Dr.
Saginaw, MI 48601
(800) 248-0280
Roofing membrane (PVC), Hypalon

EI Dupont De Nemours & Co. Inc
1007 Market St.
Wilmington, DE 19898
(800) 441-7515
Hypalon

Firestone Building Products Company
525 Congressional Blvd.
Carmel, IN 46032-5607
(800) 428-4442
EDPM

Genflex Roofing Systems
2150 Parklake Dr. NE, Ste. 240
Atlanta, GA 30345
(404) 934-8904
EDPM

Insulated Dry Roof System
152 S.E. 5th Ave.
Hillsboro, OR 97123-4125
(800) 779-1357

Manville Corporation
Rte 2 Box 363
Edinburg, VA 22824
(703) 984-6264
EPDM, insulated roofing, modified bitumen

Mule Hide Products
834 Broad St.
PO Box 1057
Beloit, WI 53512-1057
(800) 786-1492
EPDM, hypalon, roofing membrane (PVC)

Roofmart International, Inc.
2020 Industrial Rd.
Chapman, KS 67431
(800) 766-3764
Hypalon roofing membrane

Seal Dry
3300 S Woodrow
Little Rock, AR 72204
(800) 732-5379
Hypalon roofing membrane (PVC)

Sarnafil Roofing Systems
Canton Commerce Center
100 Dan Rd.
Canton, MA 20201
(800) 451-2504
Hypalon roofing membrane (PVC)

Stevens Roofing Systems
Nine Sullivan Rd.
Holyoke, MA 01040-2800
(800) 621-7663
Hypalon, TPO's (thermoplastic polyolefins), white Hypalon since the mid 1980's, and white Stevens EP brand of TPO (thermoplastic polyolefin) since 1994

Trocal Roofing System
2262-H Northwest Pkwy.
Marietta, GA 30067
EPDM, roofing membrane (PVC), Hypalon

Versico
PO Box 6424
Akron, OH 44312
(800) 992-7663
EPDM

American Society for Testing and Materials
100 Barr Harbor Dr.
West Conshohocken, PA 19428-2959
(610) 832-9585
www.astm.org
Standards for aluminum, slate, asphalt, steel

Florida Solar Energy Center
Building Design Assistance Center
(407) 638-1000
www.fsec.ucf.edu

Lawerence Berkley Labs
www.eetd.lbl.gov/CoolRoof

National Roofing Contractors Association
10255 W. Higgins Rd. Ste. 600
Rosemont, IL 60018-5607
(847) 299-9070
www.roofonline.org

Underwriters Laboratory
333 Pfingsten Rd.
Northbrook, IL 60062
(708) 272-8800
Standards for fire ratings

Western States Roofing Contractors Association
450 Peninsula Ave., Ste. B
San Mateo, CA 94401
(800) 725-0333
www.wsrca.com
Publishes the definitive "Concrete and Clay Tile Roof Installation Manual for Moderate Climate Regions"