Leonard Roofing, LLC
YOUR TRI-CITY ROOFING Contractor
Leonard Roofing, LLC
YOUR TRI-CITY ROOFING Contractor
CALL FOR FREE ESTIMATE
Licensed, Bonded & Insured
Call 276 466-2707
Over 35 Years
After Hours or Emergency Call (276) 669-3588
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COMMERCIAL ROOFING Types of Roofing Systems:
South West Virginia & Northeast Tennessee - Bristol, Tri-Cities, VA (Metro), Abingdon, VA (Metro), Kingsport, Tri-Cities, TN (Metro), and all surrounding areas.
Built-up Roofing (or BUR) is the most popular choice of roofing used on commercial, industrial and institutional buildings. BUR is used on flat or low-sloped roofs and consists of multiple layers of bitumen and ply sheets.
The Advantages of Built-Up Roofing:
Built-up roofing systems have had a long-standing popularity, due in large part to its success and proven reliability. The number of 20, 30 and 40-year-old BUR roofs still in excellent condition attests to this fact. Specifically, BUR roofs offer:
Multi-Layer Protection - the multiple layers of bitumen and bitumen saturated “felts” make a watertight barrier capable of providing many years of reliable protection from the elements.
Thermal Performance - Built-up roofing systems exhibit exceptional resistance to the conduction of heat between the exterior and interior of a building, resulting in noticeable reductions in heating and cooling costs.
Fire and Uplift Resistance – Built-up roofing systems are tested through Factory Mutual Research Corporation to meet very strict fire resistance requirements and ensure adequate uplift resistance under extreme wind conditions.
Economy – Compared to other high performance commercial roofing systems, built-up roofing is one of the best investments on the market due to its competitive cost per year of expected service life.
Components of a Built-Up Roofing System Include:
the roof deck
a vapor retarder
At the heart of this roofing system is the roofing membrane, which consists of roofing bitumen and multiple reinforcing plies of roofing felt.
Roofing bitumen is the primary adhesion/waterproofing agent used between roofing plies. Bitumen arrives at the job site in solid form, but is heated and applied as a liquid. Roofing bitumens may be either a product of petroleum refining (asphalts) or a product of the coal-cooking process (coal tar pitch).
Multiple reinforcing “plies” are asphalt-coated roofing sheets or felts installed in three or more layers to strengthen and stabilize the BUR membrane.
BUR roofing membranes can be protected from solar radiation by embedding gravel in the bitumen, applying a surface coating or applying a granular-surfaced “cap” sheet. Light-colored surfacing materials can be used to reflect heat from the building. In addition, surfacing agents can provide additional fire protection.
BUR applied for maximum performance:
It s critical to get secure bonding of the roofing felts (plies) using bitumen. To achieve this bond the roofing contractor applies thin, uniform moppings of bitumen. This waterproofs the system and ensures proper adhesion for fusing the membrane system together.
The temperature of the bitumen is critical. By heating it to the proper temperature the roofing contractor gets the right viscosity for proper mopping. The contractor heats the bitumen to its EVT or Equiviscous Temperature, the temperature at which it can be most effectively mopped into uniform layers. Each batch of bitumen should be labeled by the supplier with its EVT. Once felts are rolled into place on the heated bitumen applicators pull brooms or squeegees over the felt or use some other method to make sure that its embedded in the bitumen.
Typically, membrane ply construction is defined by headlap, endlap, and sidelap.
Headlap is the distance of the overlap that exists between the lowermost and the uppermost plies of the shingled portion of the roof membrane when measured perpendicular to the long dimension of the membrane.
Endlap is the overlap distance that is measured from where one roll of felt ends to where another begins.
Sidelap is the overlap distance along the length of the felt where one roll of felt overlaps the adjacent overlying felt.
The application of Built-Up Roofing systems is detailed work, but the professional who pays particular attention to those details such as curbs, walls, flashings or other projections that interrupt the membrane, achieves a quality, efficient, long-lasting product for the building owner.
Pitched or sloped roofs range from a moderately sloped 3-in-12 pitch to the 45-degree angle 12-in-12 slope commonly seen on A-frame roofs. Even steeper are many mansard roofs and parts of gambrel roofs, such as on barns, which may have 20-in-12 pitches.
Roofing material for pitched roofs include the following:
Composition shingles: Generically called asphalt shingles, these cover 70% of all roofs in this country. Composition shingles are divided into two types, organic or fiberglass. Organic composition roofs are manufactured with a cellulose fiber base made from recycled paper and wood fibers. This base is then saturated with asphalt and given a mineral coating on one side to resist weathering.
Composition shingles are manufactured in a wide variety of colors and are rated by their projected life expectancy, typically 20, 25, and 30 years. Most roofing manufacturers warranty their roofs for these periods, but only if their certified roofers install them. Otherwise, the manufacturers disallow any guarantees.
Fiberglass shingles are made in a similar fashion but the central core is fiberglass, which is more flexible and stronger than the cellulose materials.
Dimensional shingles: These are made from the same material as organic or fiberglass composition shingles but are much thicker. The additional layers may be sculpted to provide attractive shadow lines that give the roof a customized appearance. The extra thickness also increases their life expectancy, up to 40 years. As with composition shingles, the manufacturer s warranty generally applies only if one of their certified roofers installs the material.
Wood shingles: Shingles are commonly sawn from Western red cedar, chosen for its natural resistance to decay. Shingles are sold as No. 1, 2, or 3. Use only No. 1 for roofing because it is cut from knot-free heartwood. No. 2, from less resistant sapwood, is acceptable for siding. Shingles come in 16-, 18-, and 24-inch lengths and are sold in bundles, with four bundles to a square (100 square feet).
Wood Shakes: Like shingles, shakes are mostly cut from cedar logs. Shakes are either resawn or hand-split. A resawn shake has one side sawn to give it a more precise taper while leaving the exposed side with the typical irregular shake appearance. Hand-split shakes are more irregular but still tapered. Shakes are graded by weight: heavy or medium. They are sold in 18- or 24-inch lengths, with five bundles of 24-inch shakes covering 100 square feet with a 10-inch exposure. Most communities now require that roofing shakes or shingles be pressure-treated with a fire retardant prior to installation. Check your local codes if considering such a roof.
Tile roofs: The familiar Spanish or mission tiles are commonly made from clay or concrete. Tile shapes include the half-barrel, S-shape, interlocking, and flat. Although tiles have a life span of 50 to 100 years, they are heavy and can only be applied to roofs constructed to support such weight. Tiles are usually fitted on spaced 2-by-6 boards nailed to solid plywood roof sheathing. For steep slopes, code may require that the tiles be nailed in place through predrilled holes or supported with metal brackets.
Aluminum shingles: Aluminum shingles are available in styles that range from imitation cedar shakes to those with baked enamel colors such as red, green, black, and white. Aluminum shingles have an interlocking nailing flange on the sides so nails do not penetrate the shingle itself. They are light, weighing less than 50 pounds per square, compared to more than 300 pounds per square for average composition shingles.
Copper shingles: These shingles are manufactured in a manner similar to the aluminum shingles, including the same type of interlocking nailing fins. Copper is heavier; approximately 100 pounds to the square.
Slate: One of the oldest roofing materials around, slate is both beautiful and expensive. The best U.S. slate is made in Vermont and comes in a variety of colors. With proper maintenance, Vermont slate roofs last 100 years or more. Another key source of slate is Pennsylvania, but that slate is not as hard or as long lasting. Because of its weight, slate can be applied only to roofs built for that purpose. The material will crack easily if stepped on.
Synthetic slate: Some synthetic slate is made from fiber cement and is not recommended by the manufacturers for application in freeze-thaw climates. The fibers in fiber cement roofing products are comprised of wood or cellulose and in some cases there have been allegations that the fibers can absorb water, which may lead to roof failure. Another synthetic slate is made from ceramic tile that is lighter than real slate and not as fragile yet is highly fire resistant.
Rubber Roofs:The first synthetic rubber roofing membrane was developed in the U.S.A. almost 50 years ago and original roofs are still functioning. This suggests a product life expectancy well in excess of 50 years. Over 2 Billion square meters of membrane have been laid worldwide, from the heat of the Middle east to the cold of the Arctic.
Although slightly more expensive than traditional bitumised felt, it compares very favourably in price, with other higher quality flat roofing products. EPDM is now proving to be the more popular option for domestic projects when customers are considering the replacement of their flat roof.
EPDM is designed for maintenance access, so it s OK to walk on it. Should you require regular foot traffic or patios etc. there are various methods of covering the membrane with more durable finishes, Paving slabs, purpose made walkways, decking, etc. for patios walk ways and sun decks.
Modified Bitumen (MB) or Modified Bitumen Membranes (MBS)
Modified bitumen membranes (MBS) combines the features of a built-up roof with added tensile strength from its polymer modification. Using a reinforced sheet that is prefabricated in the plant, modified bitumen systems require a less labor-intensive application and can be applied in both commercial and certain residential applications.
Modified Bitumen modifiers and how they work:
Modified bitumens generally use a traditional waterproofing medium -- asphalt -- modified with atactic polypropylene (APP), styrene butadiene styrene (SBS), synthetic rubber or other agents that create a uniform matrix that enhances the physical properties of the asphalt. SBS and APP are the most common bitumen modifiers.
SBS (Styrene-Butadiene-Styrene) modifies the asphalt by forming a polymer network within the bitumen. SBS gives the bitumen rubber-like characteristics and improved resistance to aging and weathering. Most SBS-modified bitumen sheets are either set in hot mopping asphalt, torch-applied or adhered with cold-process adhesives. SBS-modified bitumen sheets that do not have factory applied granule or foil surfacing need some form of field-applied ultraviolet protective coating.
APP (Atactic Polypropylene) is a thermoplastic polymer which forms a uniform matrix within the asphalt. This enhances the bitumen’s performance by increasing its UV resistance, increasing its flexibility at low temperatures and improving its flow resistance at high temperatures. APP-modified bitumen sheets are generally applied using a propane-fueled torch. Applicators use the heat to soften the modified bitumen on the underside of the sheet. The sheet s bottom surface becomes a molten adhesive which flows upon the substrate and then cools to form a waterproof adhesive bond. Some APP sheets can also be applied with cold process adhesives.
The application of modified bituminous roofing is a construction process that involves the skillful arrangement of several components as specified for the process. Roof performance is determined by factors that include building design, job specifications, materials quality and suitability, application procedures and maintenance. The level of quality in the workmanship during the application process is critical.
Why choose Modified Bitumen roofing systems?
Since gaining acceptance in the roofing industry during the 1970s, the use of modified bitumen membrane roofing systems has increased steadily. Today modified bitumen membranes are the fastest growing roofing materials in the industry.
Considered a quality “hybrid” system, MBS provides the features of a built-up roof with the added tensile strength and elongation of a modified bitumen cap sheet, as well as the quality assurance of in-plant membrane fabrication uniformity and control, and reduced labor requirements for installation.
In addition, MBS products undergo the same fire and uplift resistance testing standards as BUR, providing the commercial customer full assurance of appropriate fire and uplift resistance.