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Thermoplastic Polyolefin, more commonly known as TPO, is a thermoplastic single ply roofing membrane primarily used in commercial roofing.

What is TPO?

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TPO is a single-ply low slope roof system that is made up of ethylene polypropylene rubber and talc carbon filler or fiberglass that was developed in the 1980s. TPO commercial roofing membranes are manufactured in sheets that are 10, 12, or 20 feet. The sheets of TPO roofing material are sold in rolls and come in a variety of thicknesses ranging from 40 mils to 80 mils. The thicker the TPO membrane, the more durable it is. There are three installation methods used for TPO; mechanically attached, ballasted, and fully adhered.

Mechanically Attached TPO Commercial Roof System

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In the mechanically attached method, there is no adhesive used, making it a popular roofing installation choice in areas that experience lower temperatures. The TPO membrane is fastened through the insulation boards to the structural deck at 12” on center in every seam on the roof. The seam is welded outside of the fasteners. The mechanically attached installation method is the least expensive TPO roofing option. Although the price may be attractive, it is important to remember that the TPO membrane is loose between the seams because mechanically attached roofs are only attached at the seams. Strong winds or positive building pressure can cause the membrane to create pockets of air above the insulation, which can pump conditioned interior building air into the space, eventually causing condensation on the underside of the membrane. This issue is solved by installing an air barrier below the insulation layer, improving energy efficiency, and reducing condensation. Another consideration with mechanically attached TPO commercial roof systems is the heavier localized load on the roof deck at the seams. A structural engineer should be consulted and can determine whether the structure can accommodate increased loads.

Ballasted TPO Commercial Roof System

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A ballasted TPO commercial roof system is a great option for businesses whose priority is rooftop aesthetics and roof weight are not a concern. In the ballasted roof system, a loose-laid rigid insulation is secured by several plates and fasteners to prevent excessive movement, then the insulation is covered by the TPO membrane. After the flashing and detail work are completed, the ballast stone and/or pavers are laid down throughout the commercial roof system. Ballasted commercial roof systems look nice and can be installed relatively quickly because no fasteners or adhesives are used in the installation of the TPO membrane. Since no fasteners are used, there’s little chance of hitting conduit or light systems located close to the roof deck. The pavers used in ballasted TPO commercial roof systems can be used as an outdoor patio. It is important to remember that ballasted roof systems add weight to the commercial structure, typically 10 to 15 pounds per square foot. Another concern when choosing a ballasted commercial roof system is that it can be difficult to find a leak because the TPO membrane is hidden beneath the ballasted layer of stones and/or pavers. Ballast stone also traps dirt, which can make patching and repairs to the TPO membrane difficult. Over time, the ballast material can puncture the TPO membrane, crush the underlying insulation, or create bald spots where the system is not held down at all. In areas that experience high winds, ballast stone can blow off the roof, creating projectiles below. For this reason, some building codes will not allow ballast stone, only pavers. When considering a ballasted TPO roof system for your commercial building, it is important to consider your city’s building codes and ordinances, the age and structural integrity of your building, your building needs, roof traffic, and weather patterns.

Fully Adhered TPO Commercial Roof System

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Fully adhered commercial roof systems are known for being attractive and having the least amount of lift in the TPO membrane because the entire roofing membrane is bonded to the insulation. In a fully adhered TPO roof system, the rigid insulation is thoroughly fastened and uses more fasteners than a mechanically attached roof system. After the insulation is secured, the TPO roofing membrane is rolled out and the bonding adhesive is applied to the rigid insulation and the membrane for a tight bond. If there are angle changes around walls or rooftop units, the TPO membrane is both fastened and glued to prevent the membrane from pulling. If price is your biggest concern when choosing a commercial roofing system, you may want to consider a different installation method as a fully adhered TPO commercial roof system is the most expensive TPO installation method.

Why Choose a TPO Roof System?

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TPO roofing membranes are versatile and can be installed on low slope as well as flat roofs. They come in a variety of colors and are UV resistant. The most used color for a TPO roof system is white, which is highly reflective. TPO membranes are lightweight and come in large rolls that can be easily spread across the roof during installation, reducing the number of seams, leading to a faster installation. It is also flexible and malleable when heated, meaning it can easily be wrapped around pipes and flashing. This flexibility also means that TPO is flexible with temperature and seasonal changes. If professionally installed, TPO commercial roof systems are relatively low maintenance, needing an occasional inspection or repair. TPO is impact resistant, keep in mind this does not mean that it is impervious to damage from hail impacts, but it is very durable. At Orbit Roofing we only install high quality TPO roofing materials to manufacturer specifications to give you the best commercial roofing solution for your business.

How Does Hail Affect a TPO Roof System?

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Hail damage to TPO roof membranes include fractures or tears in the TPO or its reinforcement. The most sensitive areas of a TPO roof system tend to be in the lap seams of mechanically attached roof systems or those used for fastening underlying insulation boards. It is important to have an experienced commercial roofing contractor like Orbit Roofing inspect your commercial roofing system for hail damage following a hailstorm. Damage to TPO roofing systems presents differently from most residential roofs. Large hail fractures can be seen plainly, but smaller fractures may require closer inspection and manipulation of the membrane to identify dents in the underlying insulation.

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