Guide to IB PVC Roofing
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One the most durable roofing materials that many homeowners don't consider is IB PVC. Roofing systems that use a PVC base for an IB membrane are usually reinforced membranes with glass and plastic stabilizers. The result is the ability to stretch roofing material over a large surface area. They are available in several colors to match the exterior of the building or offer a unique contrast. Heat or welding materials seal the seams of the membrane. A process known as plasticizer migration causes plasticizer polymers to leach out of the sheet, causing the roof to become brittle. The PVC roof material prevents this by using a thicker membrane for a longer lifespan.
Minimum costs: Basic costs of IB PVC roofing start out at $4.00 per square foot including labor.
Maximum costs: More complicated systems that use thermoplastic materials cost upwards to approximately $6 per square foot including labor.
The installation of a PVC IB roof is fairly straightforward depending on the slope or pitch of the roof. The installation will also take into account the structure of the building and the type of vent stacks in the roof. Vent stacks that contain high levels of pollutants may need additional hybrid PVC materials to keep the material flexible. Plasticized roofing material requires the understanding of welding and seam blending. The purpose of PVC IB roofing is to make a practically watertight solution for a flat or very low pitch roof.
Thermoplastic Olefin (TPO)
TPO is a PVC blend that is reinforced with polyester. The material has a flame retarder embedded into the material to make up for the reinforced materials added to the lamination of this type of sheet roofing. The seams are welded using hot air or heat welding. No chemicals are used for the seams due to the addition of UV and fire retardant materials. This form of PVC heat weldable roofing can create the appearance of a continuous membrane. Thermoplastic Olefin contains several filler components for flexibility and environmental friendliness. TPO carries a higher cost but includes an Energy Star rating that rates the roof material as a cool roof component. This means that heat loss is minimal, and the roof remains cool to extend the life of the substrate.
PVC alloy contains a mixture of materials in a PVC base to achieve additional rigidity. This usually consists of a mix of polymers and polyester or fiberglass reinforcements. These reinforcements help to resist tearing and strength loss on a fastened roof system. PVC alloy can be used in conjunction with basic PVC roofing for tensile strength in key areas of the roof that require it. This can include joints and areas of flashing for chimneys and roof vents. PVC alloy is typically used in a flat roof to buffer the effects of water pooling and debris pollution.
Rough Substrates & Roof Attachment
Some flat and slightly sloped roofs contain a substrate or material that is not completely smooth. Vinyl IB roofing usually contains a polyester-type backing that adds a cushion onto slightly rough surfaces for adhesion. There are various vinyl accessories that can be used on the roof for wall flashing as well as prefabricated pipe and vent flashing. Large prefabricated panels can be installed to make installation quick and efficient. The PVC roof is usually attached by one of three methods:
The PVC material is secured only around flashing areas such as pipes and roof vents. A ballast material, such as stone or paving rock, holds the PVC roof in place. The ballast acts as an anchor to the roof on single-ply systems. The majority of the membrane is not directly attached to the roof but relies on the weight of the ballast to hold it down.
The PVC roof is attached to the substrate using an adhesive. The adhesive depends on the type of roof texture and material. This form of roofing is used the least and relies on shorter segments of PVC membrane material to achieve a long-lasting adherence to the roofing deck and substrate material.
This is one of the most common forms of PVC roofing and is used in some forms of low pitch roofs. The PVC material is laid across the substrate material and attached using special bolts or screws. Some types of roof use fasteners that are a form of tape or quick drying adhesive in addition to the decking screws.
Advantages of IB PVC Roofing
An airtight home is usually highly insulated. An IB roof solves this problem by creating a moisture-proof barrier with an exceptionally high r-value. PVC roofs can withstand moisture and the pooling of water on the surface. They are also in a unique class of their own in fire safety and prevention. The roof itself will resist a flame and resist being a source of fuel in a fire. In addition to fire resistance, the roof has a considerably lower threshold for heat. A typical tar roof will gain up to 90 degrees Fahrenheit in temperature. A PVC-based roof may gain only 10-20 degrees Fahrenheit in temperature. Many IB roofing systems contain a lifetime warranty and will typically pay for itself over an extended period of time. IB PVC roofing also has a distinct commercial advantage. Due to the flexibility of PVC, the roof can include custom logos and application of multi-color materials for commercial application.
Disadvantages of IB PVC Roofing
IB roofing usually requires additional equipment to weld seams together for continuity in the structure of the roof. Roof pitch is also an important thing to consider. Steep pitched roofs are difficult if not impossible to install a PVC membrane on. An IB PVC roof installation can quickly include additional costs due to the proprietary flashing required. IB roofing is not a "mix and match" type of roofing where designers could use metal flashing with various shingle varieties. The entire system will require expertise in using PVC material and the combination of PVC components that make up the unique style of the roof.
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Last updated on Jan 12, 2017