EPDM

What is EPDM?
EPDM is an elastomeric compound that is manufactured from ethylene, propylene, and a small amount of diene monomer.  These ingredients are synthesized to produce a product that exhibits a high degree of ozone, ultraviolet, weathering and abrasion resistance, and outstanding low temperature flexibility.  These ingredients also contribute to resistance to acids, alkalis, and oxygenated solvents (i.e. ketones, esters, and alcohols).

What makes EPDM membrane suitable for non-exposed assemblies
(i.e. protected membrane applications and double slab installations)?

Structural deflection, improper drain placement, or an insufficient number of drains can result in low areas on the roof that allow moisture to collect and pond over a period of time.  Therefore, one of the most important characteristics of a roofing membrane is its moisture resistance.  EPDM has excellent moisture absorption resistance that makes the material more tolerable to entrapped moisture than most roofing membranes.  Since the early 60s, the material has been successfully used in canals, pond lining, and other irrigation systems before its debut as a roofing membrane.

What are the available thicknesses and types of EPDM single-ply membrane?
EPDM membrane is manufactured in various thicknesses (.045” to .090” thick) and is available as a non-reinforced or reinforced sheet (depending upon application). 

Reinforced membranes contain an internal fabric that is completely encapsulated within the EPDM membrane sheet and is available in various thicknesses (.045” to .075”).  Occasionally, a fleece layer can be added to the underside of the sheet that serves as a built-in underlayment for direct re-roof applications over certain types of existing roofing material.

EPDM is also manufactured as vulcanized (cured) or non-vulcanized (uncured) membrane.  Vulcanized membranes have set physical properties due to the vulcanization process and exhibit consistent behavior throughout the sheet that allow the membrane to have memory.  This means when the membrane is stretched, it will return to its original state.  On the other hand, non-vulcanized EPDM does not have set physical properties because it is not cured when manufactured.  This makes the uncured material ideal for use as flashing where the materials can be stretched, formed, and shaped.

Are EPDM membrane roofing assemblies fire retardant?
An EPDM roofing assembly can be designed to meet Underwriters Laboratories (UL) and Factory Mutual (FM) fire classifications.  Like in many other roofing assemblies, the fire retardency level will depend on roof slope and the various components utilized.  Current UL and FM publications contain numerous listings of various approved assemblies.

Does hail affect the physical characteristics of EPDM?
EPDM passes the Factory Mutual (FM) 4470 testing procedure that includes hail resistance, and does not show fatigue from the impact the membrane must endure during a hailstorm.  Hail warranties are available and offer protection against 1 inch and 2 inch diameter hail.

How does EPDM perform in expansion and contraction situations?  Should relief or control joints be utilized the same as on a built-up roof?
Relief or control joints are commonly used with built-up roofs to subdivide a larger roof area and segregate possible damage into one small area.  EPDM, due to its flexibility (-49F) and elongation, will accommodate stresses caused by temperature extremes, structural movement, and deflection.  In cases where the building is designed with expansion joints, the design should be carried all the way through to the roof and an expansion joint should be incorporated into the roof design.

What can I put on snow and ice to facilitate melting and not affect the EPDM or my warranty?
Calcium Chloride will work in most conditions.  It can either be spread over the area of concern or placed in a nylon stocking and placed along/around the areas in need of melting.  While the Calcium Chloride will not harm the EPDM caution should be taken in regards to where the melt water will drain, and verification that it will not affect the materials and/or vegetation it comes in contact with, should be obtained prior to placing the Calcium Chloride on the roof.

TPO

Thermoplastic polyolefins are in the thermoplastic elastomer family and are commonly referred to as TPO in the single-ply roofing industry.  TPO single-ply membrane systems have been engineered to provide premium performance at a very cost-effective price. Strong, flexible, and durable membranes are suitable for use in all types of single-ply systems: Mechanically Attached, Fully Adhered, and Ballast Applied.

TPO-based products have been used in various applications, including the automobile industry since the 1980s, and have seen their usage continue to expand.  In 1989, TPO-based membrane moved into the roofing industry as a non-reinforced sheet. In 1993, the original non-reinforced TPO membrane was replaced with membranes containing reinforcing fabric. Since that time, the TPO single-ply roofing market has grown to hundreds of millions of square feet annually with TPO membrane comprising the fastest growing segment of the U.S. single-ply roofing industry.
Make up

TPO roofing membrane is typically based on polypropylene and EP (ethylene-propylene) rubber polymerized together using state-of-the-art polymer manufacturing technology. This technology enables the production of TPO membranes that are flexible at low temperatures without the use of polymeric or liquid plasticizers. Unlike some other popular thermoplastic roofing membranes, the TPO polymer does not contain chlorine and no chlorine-containing ingredients are added during sheet production. This lack of chlorine has allowed TPO marketers to tout their membrane as an environmentally safe, “green” product.

Installation/System Types
TPO roofing membrane is typically installed using mechanical fasteners and plates placed along the edge of the sheet and fastened through the membrane and into the roof decking.  Adjoining sheets of TPO membrane are overlapped, covering the fasteners and plates, and joined together with a minimum 40 mm (1 1/2 in.) wide hot air weld.

In the field of the roof, proper membrane width and fastener spacing is determined after calculating potential uplift loads based on building height, surrounding terrain and the wind zone in which the building is located. The fastener/deck combination must exhibit adequate pull-out resistance to withstand the fastener loading generated during uplift. The membrane and the welded seam must also resist the forces generated by wind uplift. Along the perimeter of the roof, where the highest wind loads are experienced, reduced width membrane is installed to reduce the fastener and seam loading.

The membrane may also be fully adhered to an insulation or deck material using an adhesive. Insulation is typically secured to the deck with mechanical fasteners and the TPO membrane is adhered to the insulation. This type of system is highly resistant to wind and its associated uplift forces. Since the sheet is 100 percent affixed to the substrate, the membrane does not flutter due to associated wind forces. With no sheet movement due to the 100 percent attachment of the membrane, the fully adhered system is ideal for very visible roofs such as domes or other high slope applications.

Welding
One of the primary benefits of TPO membrane is the ability to fuse the sheets together with a hot air weld.  The welding process results in a bond that is actually stronger than the sheet itself. Flashing details, such as exhaust vents, pipes and parapet corners are also completed using hot air welds and flashing material (typically non-reinforced).

TPO membrane has a wide window of weldability, allowing the roofing applicator to complete hot air welds consistently in a broad temperature range. Since weld integrity is critical to the performance of the roofing system, it is imperative that the membrane welds properly in a wide range of ambient temperatures. TPO is a thermoplastic material and does not “cure” on the rooftop once installed. This allows the sheet to be repaired with proper surface preparation after rooftop exposure.

Reflectivity
Another important characteristic of TPO membrane is its high level of reflectivity. Because of this, white TPO membranes can meet and even substantially exceed the U.S. Environmental Protection Agency’s ENERGY STAR performance levels. Those ENERGY STAR marks that have been posted on refrigerators, water heaters and other appliances for years now can be seen on rolls of white TPO membrane. White TPO membranes typically display reflectivity ratings in the high 80 percent range when new (ENERGY STAR specifications require 65 percent minimum) and in the low 80 percent range after three-year rooftop exposure with cleaning (ENERGY STAR specifications require 50 percent minimum). TPO membranes are highly resistant to mold and algae growth, which can degrade the overall reflectivity of the roof and reduce anticipated energy savings.

Spray Polyurethane Foam

Overview
Spray polyurethane foam, commonly referred to as SPF is a spray-applied insulation foam plastic that is installed as a liquid and then expands many times its original size.  Spray polyurethane foam can be adjusted and have many different physical properties depending on the use desired.  For example, the same basic raw materials that can make insulation foam semi-rigid and soft to the touch also creates high density roofing foam that is resistant to foot traffic and water.  Specialized equipment is used to apply the spray polyurethane foam and proper technical training is important in order to get the best results.

Spray polyurethane foam is the king of building materials for multitasking.  For moisture it can provide high levels of R-value, while providing air barriers and assistance in moisture control in buildings.  For roofing, spray polyurethane foam insulates and eliminates thermal bridging through fasteners or gaps in decking while providing a long-lasting roofing system that has a life that can be extended by re-coating  or recovering in an average of > 10-15 years.  As a result spray polyurethane foam is used in a wide variety of applications including, but is not limited to:

1. Roofing
2. Air barriers
3. Commercial and residential insulation in walls, ceilings, attics and basements
4. Industrial insulation for pipes and tanks, cold storage facilities, freezers, walk-in coolers, and climate controlled buildings such as product storage and clean rooms
5. Flotation for boats, ships, barges, floating docks, etc.
6. Higher density spray polyurethane foam has been used to increase the structural strength of wings in airplanes

Why is SPF Energy Efficient?
• Polyurethane foams have one of the highest insulating R-values per inch of all the available products on the market today.  With typical values ranging from 3.5 to 6.0 per inch, it is possible to maximize efficiency, increase space utilization and reduce operating costs, while having thinner walls and a lower profile roofs.
• Studies show that increasing the thickness of your roof insulation by 1” or more above the ASHRAE required thickness significantly reduces your energy costs.
• SPF sealants that are applied to cracks around window frames expand to fill energy-wasting (escaping) gaps around the window, which increases your buildings energy efficiency.
• Energy studies performed by Texas A & M on their own roofs show the energy cost reductions obtained by applying SPF to more than 8 million square feet of roofing paid for the cost of the retrofit in a little over three years.
• Cool roofs (using reflective plastic coverings over SPF insulated roofs) bounce sunlight and radiant heat away from a building, helping the structure stay cool and reducing energy use for cooling.

Energy Calculators:
• http://www.eere.energy.gov/consumer/calculators/
• http://www.specright.net/

Sustainability/Life Cycle Costing

Adverse Weather Performance
SPF roofing systems have exceptional sustainability characteristics.  They save energy, are resistant to high winds, protect the substrate against damage from hail and wind driven missiles, and are renewable.  SPF has proven durable during recent hurricanes, during hail storms, and other adverse weather conditions.

COATINGS

Acrylic/Silicone/Urethane
Elastomeric Roofing Membranes are either water-based or moisture cured, spray-applied liquids, which cure to form a seamless 100% elastomeric membrane specially designed to seal the entire roof.  Most elastomeric coatings are ENERGY STAR® qualified reflective products that will help to reduce building temperatures and are listed by the Cool Roof Rating Council for solar reflectance and thermal emittance.  Elastomeric roof coatings offer high tensile strength and elongation, and are virtually undamaged by extended exposure to solar ultraviolet energy.

Advantages:
• ENERGY STAR® qualified reflectivity can dramatically decrease building temperatures
• Highly reflective and listed by the Cool Roof Rating Council for solar reflectance and thermal emittance
• California Title 24 Compliant
• Offers high tensile strength and elongation, and is virtually undamaged by extended exposure to solar ultraviolet energy
• Low VOC, non-flammable, and presents minimal hazard to the applicator or the environment
• Cures and becomes stronger under the sun’s ultraviolet rays
• Water-based for superior protection and easy application
• Limited material warranty available for up to 10 years
• Guarantees available for up to 20 years