Modified Bitumen Roofing:
Modified Bitumen roof systems are asphalt based and provide superior waterproofing characteristics. The typical life span for these systems is about 10 to 20 years. Modified Bitumen roofs are usually installed as a two ply system and are always fully adhered. These roof systems are made up of asphalt that has been modified with a polymer to create plastic or rubber like properties. The modifiers provide increased resistance to brittleness, cold temperatures and increased elasticity and strength.The most common modifiers are APP (Atactic Polypropylene) and SBS (Styrene Butadiene Styrene).
APP modifier, when added provides a plasticized quality to the asphalt. By adding 30% APP, the asphalt is able to be stretched up to 50% of its original length. The APP modified asphalt is reinforced with a polyester mat and manufactured into a roll product. These membranes have extra asphalt on the back side which allows it to bond to the substrate through applications such as heat welded or torch applied methods.
- Torch Applied – The APP modified membrane is applied with the use of an open flame torch to melt the bottom side of the sheet as it is being applied.
- Heat Welding – The welder is used to blow out hot air which fuses the back side of the membrane to the substrate during application. This method is a safer alternative than torch applied, as it is less of a fire hazard.
SBS modifier when combined with asphalt, produces rubberized properties. By adding 10%-15% SBS to the asphalt it is then able to be stretched six times its normal length and then can return to its original size once relaxed. This helps deal with the stresses of normal expansion and contraction of a roof. Reinforcements for SBS modified asphalt include fiberglass, polyester, or a combination of both. These membranes are most commonly applied with hot asphalt or cold adhesive. There are also self adhering SBS membranes, which contains an adhesive backing.
- Hot Asphalt application – Hot Asphalt is applied to the felts or substrate with the use of a machine or is physically mopped down and then the membrane is laid over the hot asphalt. The hot asphalt acts as the adhesive and allows the membrane to bond to the substrate.
- Cold Adhesive – The modified membrane is set in a cold process using specially formulated asphalt based adhesives as it is being applied.
- Self Adhered – The bottom surface of the membrane is covered with an adhesive and release paper. Once the paper is removed the adhesive allows the membrane to adhere to the substrate without the use of additional adhesives.
There are numerous surfacing options for APP and SBS modified roofs including factory applied mineral surfaces, gravel surfaces, smooth surfaces, and "cool roof" coatings, which are highly reflective coatings that can help save on cooling costs.
TPO (Thermoplastic Olefin or Polyolefin) Roofing:
TPO and PVC are single ply roof membranes that are engineered to provide durable and long lasting roof systems. The manufacturers’ warranties for these systems range from 10 to 30 years. TPO is the fastest growing low slope roofing product on the market. TPO (thermoplastic Polyolefin) is a flexible light weight material that is a combination of rubber and vinyl and all the seams are hot air welded. It is available in 45, 60, and 80 mil. in thickness and is comprised of three layers - A TPO Polymer base, A strong polyester or fiberglass reinforced center, and a durable Thermoplastic Polyolefin compounded top ply. PVC (Polyvinyl Chloride) is also known as a vinyl roof and is typically reinforced with fiberglass mats or polyester. Both TPO and PVC roof systems are highly resistant to tears, impacts, punctures, and are algae resistant. These roof products contain colorants and flame retardants and come if a variety of colors, with white being the most popular. The white roof is considered to be a “cool roof” as it is an energy efficient product that reflects the suns heat. TPO and PVC roofs are environmentally friendly and recyclable products.
There are three standard application methods for TPO and PVC Roofing:
- Fully Adhered – this system requires using a solvent or water based adhesive to adhere the rubber to the substrate or insulation board.
- Mechanically Fastened – This method is done by attaching the membrane to the deck using mechanical fasteners along each loose edge of the material.
- Loose Laid / Ballasted – this application is done by fastening the perimeter of the membrane and then the roof is covered with gravel to secure the loose laid sections into place.
EPDM Rubber Roofing:
EPDM Rubber is one of the most popular types of low slope roofing materials. It is a high performance synthetic rubber that is able to withstand extreme temperatures. EPDM is an environmentally friendly product that consists of Ethylene, Propylene, Diene, and Monomer. These ingredients are synthesized to produce a high resistance to; the ozone, weathering and abrasion, flexibility in low temperatures, and thermal shock durability. EPDM thickness ranges from 45, 60, to 90 mil., with the most common being 45 and 60 mil.
The EPDM rubber has a smooth surface and is available in black and white. The white membrane is created with added dyes or pigment to enhance the UV resistance and reflect the sun’s rays. The manufacturers’ warranties for EPDM range from 10 to 30 years.
There are three standard application methods for EPDM:
- Fully Adhered – this system requires using a solvent or water based adhesive to adhere the rubber to the substrate or insulation board.
- Mechanically Fastened – This method is done by attaching the membrane to the deck using mechanical fasteners along each loose edge of the material.
- Loose Laid/ Ballasted – this application is done by fastening the perimeter of the membrane and then the roof is covered with gravel to secure the loose laid sections into place.
Hot Asphalt Roofing:
Built-Up Roof systems consist of multiple layers of felts, fabrics or mats that are saturated with bitumen, either asphalt or coal tar pitch. The surface of the roof can have a gravel application, a mineral cap sheet or a weather resistant coating to help protect the bitumen and felts from premature weathering.
BUR is one of the oldest low-slope roof systems that are still applied to commercial roofs today. BUR's 120 year track record is unsurpassed in the roofing industry and continues to offer building owners dependable service.
PEAK PERFORMANCE Roofing has thousands of square feet of installation experience with these types of roof systems. A PEAK PERFORMANCE Roofing representative can review the performance characteristics associated with the various Modified Bitumen and Built-Up Roof systems so the right roof system can be selected based upon the conditions associated with your individual building.
