The Flat Roof Dictionary
Choosing the right flat roofing system is essential for any home or building. Consider that if your flat roof leaks, cost of repair will include not only roofing contractor’s labor and material charges, but also the cost of interior repairs, as well as damaged equipment, products inventory, furniture, etc. Waterproofing a roofing system is critical to the longevity of the roof itself. It deters the harmful effects of mold and rotting from water collection and protects the overall structural integrity of the building.
A good flat roof must require easy maintenance, be easily repairable during any season and at any outside temperature, as well as provide long lasting protection from the elements. When considering re-roofing options for commercial facilities, it’s important to keep in mind that not all “new” roofing materials are compatible with “old” materials. Case in point: PVC membrane roofing products are not compatible with asphalt-based products. Also note, most single-ply membranes are not fully adhered to the roof surface and need a recovery board to both protect the membrane from the old roof surface and lessen the condensation build-up under the new membrane (an accumulation of moisture trapped below the new membrane will saturate the recovery board and deteriorate the roof deck).
BUILT-UP-ROOF
Built-Up Membrane Roofing Systems (BUR) are actually as simple as they sound. They’re fabricated with layers of bitumen with alternating plies of reinforced felts. The simplistic layer design gives this unique membrane outstanding water and weathering resistance. According to the National Roofing Contractors Association, BUR Membranes have been used in the U.S. roofing industry for more than 100 years. Generally known as “tar and gravel” roofs, BUR membranes have been a time-tested and trusted choice for simple flat-roofing. BUR Systems have an advantage over other flat roofing systems: they can be hot applied or cold applied. This flexibility relieves some of the limitations of common roof installation, making it easier for roofers to install without compromising time schedules or your company’s business.
COLD APPLIED
Cold Applied Waterproofing Systems are an increasingly popular choice for sealing new roofs and roof restoration. The process is much safer than hot applied waterproofing systems – free of harmful installation components such as open flame and intense heat. The fiberglass reinforced polymers provide seamless waterproofing around potential flashing conditions. The Cold Process Roof System out performs hot asphalt in re-roof applications because it will not blister up due to the heating of moisture in the existing roof normally associated with applying hot asphalt. What’s more, the Polyester Mat used in the Cold Process System is far superior in strength and flexibility to organic or fiberglass felts used with hot asphalt. The Cold Process Coating itself, does not get brittle in cold temperatures as does hot asphalt.
3G Industrial Roofing specializes in Cold Applied Waterproofing Systems and installs them effectively and affordably. Contact one of our friendly roofing experts to find out how to implement your own Cold Applied Waterproofing System.
HOT APPLIED
Hot Applied Waterproofing Systems are the most commonly used method of waterproofing roof surfaces. It is more dangerous to install than cold applied waterproofing systems, as it requires extreme expertise due to fire hazard and intense heat. It creates a seamless, nearly impenetrable water-tight seal that rivals none. Due to the extreme nature of installation, Hot Applied Waterproofing Systems should only be installed by exceptionally skilled and trained professionals.
MODIFIED BITUMEN
Modified Bitumen (MB) roofing is an asphalt-based, close cousin of the Built-up-Roof (BUR) designed for buildings with low-slope or “flat” roof structures. A bitumen is a term applied to both coal tar pitch and asphalt products. Engineered modified bitumen roofing membranes originated in Europe in the mid 1960's and have been used successfully in the United States and Canada since approximately 1975. Modified Bitumen Roofing Systems are designed to withstand harsh exposure to extreme environmental elements. The framework for Modified Bitumen Roofing Systems is a five-layer combination of roofing components. Usually applied by heating up the underside of the roll with a torch provided a significant fire hazard and was outlawed in some municipalities when buildings caught fire and some burnt to the ground. With proper installation and maintenance this is a good system.
Single Ply Roof Membranes
* Typically, there are three installation methods. Ballasted at 1,000 lbs/sq or 10 lbs/sq.ft. with large round stones. Mechanically attached is another method and is suitable in some applications where wind velocities are not usually high. Fully adhered is the most expensive installation method but proves to give the longest performance of the three methods.
EPDM Rubber Roofs
– oldest single ply roof, and most common roofing system installed today. EPDM rubber roofing is popular due to its relatively low cost and installation methods which do not require any special equipment or machinery. Despite its popularity, rubber roofs are very prone to roof leaks as seam overlaps are glued, and adhesive usually fails within 7-10 years of installation. Once seams begin to fail, rubber roofs require total re-seaming and re-flashing of roof curbs and penetrations. Also be aware that roofing manufacturers do not generally require roof applicators to be certified and licensed. Therefore there is a great chance that your roofing contractor is not properly trained in installation of EPDM rubber roofing materials. EPDM has been commercially used for over 40 years and the membrane itself will usually not fail without exterior factors affecting its performance. Most EPDM roof leaks are due to seam failures and installation errors.
Torch Down Rubber - The major problem with torch down rubber roofing is that small cracks develop throughout the material especially at the seams which are every 3 feet. Another aspect which bears mention is the fires which have developed long after the last torch was put out due to smoldering insulation and other ignitable materials the flame comes in contact with. Most torch down roofs that were never protected with an aluminum coating, will last only 5 years before needing to be serviced.
PVC Roofing
– second oldest single-ply roofing membrane on the US roofing markets. PVC roofing was originally developed in Europe, during massive re-building of post WW II era, when enormous numbers of new multi-family apartment buildings, stores, malls, schools, factories, etc., where built. All these buildings had flat roofs and required a long-lasing solution against roof leaks, which would also be economical and easy to repair in 10, 15 or 20 years. What is PVC Roofing? PVC roof is a single-ply membrane that consists of two plies or layers of PVC material with a polyester reinforcement scrim between the layers. Top ply has special additives to make the membrane UV stable, prevent curing, plasticizers to make it flexible and pigments for color. PVC roofing is a thermoplastic single-ply membrane, and unlike EPDM rubber roofs, the seams and flashing of PVC roofs are hot-air welded, creating a physical bond. PVC roofs are naturally Cool Roofs, with white outside surface being the standard color (unlike EPDM rubber’s black surface). Cool Roofs provide tremendous energy savings in southern climates where there is a lot is sun light and HVAC equipment has to work much more than in northern climates, to keep the inside temperature at comfortable level, for building’s occupants.
TPO Roofing
– the newest single ply flat roofing material on the US market. In US, TPO roofs are designed to be as inexpensive as EPDM rubber roofing, yet provide all the benefits of PVC roofing: Hot air welded seams, ease of repair and Cool Roof properties. Despite good intentions and the general idea behind TPO roofing, numerous TPO roof failures already accruing on commercial roof installations and future potential roof failures may haunt TPO roofing manufacturers and contractors installing these products for many years. (Search the web for "problems with TPO" and "TPO lawsuits") The nature of TPO roof is to be economical, which requires the manufacturing costs to be as low as possible. What TPO manufacturers decided to do, is to use cheap fillers in manufacturing process, to reduce the cost, as well as make the weathering surface of TPO membrane (top ply, above the scrim – the most expensive part of TPO roof as it requires the components to keep the roof UV stable and to remain pliable) as thin as they realistically could. This and many other factors have caused numerous “waves” of TPO roof failures and consequently, major material reformulation, and introduction of at least three new generations of TPO roofing in short 16 years, since introduction of TPO roofing to commercial flat roofing market. In the period between 1999 and 2002, all major American TPO manufacturers pulled their products 0ff the shelves and went through major reformulation to eliminate material and weld failures associated with first generation of US TPO products. Today, most TPO roofs installed represent 2nd generation.
First Generation TPO Failures
SPRAYED POLYURETHANE FOAM (SPF):
Spray foam roofing starts out as two liquid components - an isocyanate, known as the "A" component, and a resin (or polyol), the "B" component. When the liquids are mixed at a one-to-one ratio, a chemical reaction occurs and the mixture expands 20 or 30 times forming a solid, monolithic (seamless), closed-cell, fully-adhered roof system that provides excellent water-resistance and thermal insulating abilities. We do not recommend this system as it is unproven and unstable and fails often due to surface breakdown. After failure the foam has to be removed which is a costly procedure for a new system to be applied. (The pictures explain the reason for our concern).
All of the above flat roofing products end up in our landfills after they reach the end of their service life. None of them are suitable for recycling. It also takes about 400 years for asphalt to naturally degrade. For modified roofing such as Epdm, APP, SBS and TPO, it will take a much longer period to degrade, and bear in mind that there are billions of square feet of Asphalt, Modified Bitumen, TPO, Tar & Gravel roofs coming to the end of their life cycle each year, in US alone. 99% of all these roofs will end up in landfills. We are glad to offer our Composite Restoration System as an environmentally friendly alternative that eliminates the need for tear-off.
Cold applied liquid membranes
The coating cures to form a rubber-like elastomeric waterproof membrane, capable of stretching and returning to its original shape without damaged cold applied membrane coatings. An increasingly popular choice for new roofs and roof refurbishment, this type of roof membrane is generally referred to as Liquid Roofing and involves the application of a cold liquid roof coating. No open flames or other heat sources are needed and the glassfibre reinforced systems provide seamless waterproofing around roof protrusions and details. Systems are based on flexible thermoset resin systems such as polyester and polyurethane. In the United Kingdom, liquid coatings are the fastest growing sector of the flat roof refurbishment market. Between 2005 and 2009 the UK's leading manufacturers have reported a 70% increase in the roof area covered by the coating systems supplied. However because most cold applied liquid membranes are not fully re-enforced the are prone to crack as the roof expands and contracts. We install only fully re-enforced liquid roofing involving the application of a monolithic, fully bonded, liquid based coating to a roof. The coating cures to form a rubber-like elastomeric waterproof membrane, capable of stretching and returning to its original shape without damaged cold applied membrane coatings.
Composite Restoration System
Our System is a combination of a BUR (Built-up Roof) and a Cold Applied Liquid Membrane. The BUR has by for the best track record for longevity (some BUR's have lasted for 75 years), but because it is labor intensive and is not considered a "cool roof" it is used less every year. Cold Applied Membranes are fast becoming popular as they are considered a "cool roof". Most Cold Applied Liquid Membranes typically crack in only a few years as the roof surface moves due to weather conditions and/or foot traffic. Our system has taken the best that these two systems offer and combined them to create a fully adhered, multi-layer, fully-reinforced cold applied liquid asphalt with with continuous embedded stitch-bond polyester mat top coated with a liquid reflective "cool roof" coating. With little comparative expense our system can last the life of your building. Click here to Learn more about our system.