Yes. The standard is ASTM E-917, "Standard Practice for Measuring Life-Cycle Costs of Buildings and Building Systems".

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Adhesion to a roof substrate is critical. Selecting the right base coat is imperative. National Coatings Corporation has designed a number of coating solutions to meet these challenges. Our AcryShield A501 is specifically designed for use over spray foam. AcryShield A502 is able to be used on any single ply substrate without the need for additional etching rinses. A503 is designed to adhere to metal and asphalt based products.
Ultimately, it is important to follow the manufacturer's directions and cautions when applying any roof coating.

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A "green roof" system can be defined in one of two ways. First the green products term is sometimes used to describe an "environmentally friendly" roof where the green roof system surface color is white and the roof assembly is well insulated with an energy savings "green roof" coating. A second definition implies the use of organic vegetation such as gardens, planters and trees installed on the roof.

Advantages: 

- It can attenuate the rain water coming off the roof.

 

Disadvantages:

- Heavy weight (acrylic coating system is light weight).

- Plant species are not always attractive, especially when drought resistant plants are required.

- It’s hard to locate leaks.
- The building structure must be designed for the heavy load and the increased load as the plants grow.
- Lower solar reflectance than an AcryShield Cool Roof.

Neither is better, but they are different with advantages and disadvantages for each. Either will reduce the cooling load on the building by reflecting the IR portion of the solar spectrum. The white coating is a roof maintenance practice. This is an important distinction, as the coating does not add additional "dead load" or weight to the roof. Thus if the roof includes two roofs; the original and a recover, then the coating can be applied while still complying with the appropriate building code. There are also tax advantages and financial implications that may favor a roof coating over a new white roof. The white roof is a true "roof" acting as the primary waterproofing. The roof coating is usually not the primary waterproofing but rather acts as the first echelon of protection, keeping water out and shielding the membrane. Remember that with any type or color roof, a roof coating can be applied to prolong the roof life.

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The roof will collect dirt during its life and will have lower albedo. Studies conducted by Lawrence Berkeley Laboratory have shown that the solar reflectance drops to about 80% of its original value. Of course this is critically dependant on the "micro climate", i.e. how dirty the locale is.

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No. The correct thickness should be driven by the manufacturer's recommendation. (NCC suggests a minimum of 16-24 dry mils depending on the condition of the roof)

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This is an exudate that contains water-soluble components from the roof coating. These materials easily wash off and should be removed if additional coating is to be applied. Not removing these will interfere with intercoat adhesion.

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Definitely YES. A primer is not a replacement for thorough cleaning. Remember, the primer is designed to adhere to "structurally sound" (read: dirt free) substrate. Without precleaning, the primer will not make the needed contact with the roof substrate. Any chemical reaction to promote adhesion that may normally take place will be impeded by the presence of dirt and degraded roofing materials.

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Once the roof has been cleaned and dried, press a 3-4" long piece of 2" masking tape to the roof using hand pressure. Then, peel the tape off the roof. If it comes off easily, and or is laden with dirt, degraded roofing materials and other particulates, the roof is not cleaned satisfactorily. Reclean and dry the roof and repeat this test. This test should be conducted in several areas around the roof, especially in ponded or other dirty areas.

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Yes. One easy method is to apply the roof coating to the prepared roof surface and while still wet, imbed a 1" wide cloth strip. The strip should be ~12" long, but imbed only about 6" of the strip. Allow this to dry. If wet adhesion properties are needed, adhere a 12" diameter by 2" sheet metal cylinder to the roof substrate using a caulk. When the caulk is dry, fill the area with water and wait for one week. After the dry/immersion period, attach a small fish scale (the kind used by sport fisherman, available at sporting goods stores) to the free end of the cloth strip. CAREFULLY, cut the 1" wide sides of the strip that is imbedded in the coating, being careful not to cut into the roof substrate. Pull slowly on the fish scale, pulling the 1" wide cloth strip away from the roof substrate. Read the weight (force) required as the cloth strip is pulled away. This method is similar to the ASTM C-794 adhesion test.

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FM is a group of 3 property insurance companies who insure the majority of the Fortune 500 buildings in the U.S. FM also includes Factory Mutual Research Corporation (FMRC) who conducts research and develops testing protocols for evaluation of building components. FM 4470 is the standard protocol for evaluating roofing systems. It includes pass/fail tests for fire resistance, wind uplift, hail resistance and water resistance.

Underwriters Laboratories evaluates a myriad of building and construction components "In the interest of public safety". UL evaluates low slope roofing systems for fire under the UL-790 protocol.

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No. Only the entire roofing system can be "listed" by UL. This includes all components from the roof surface (coating) down to the roof deck. Components are not tested individually, but rather as a complete system.

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The test has three parts. The first is "Spread of Flame". A roof mockup measuring 4'x 10' is made and allowed to condition for 30 days. Then the assembly is placed at an incline in a chamber that simulates a 26 MPH wind. A flame is created using a gas burner across the bottom of the assembly and allowed to propagate up the incline for 10 minutes. The flame spread is measured and rated according to Class A, B, C with A being the least flame spread (best rating).

The second part is "Intermittent Spread of Flame". Here the same process is recreated, but the flame is turned off and on during the test. Again the flame propagation is rated as A, B, C.

The third test is the "Burning Brand Test" where a pine lattice (called a Crib) is set afire and placed on the roof assembly. If it burns through to the deck, it fails that rating. "A" rating would resist a 12'x 12" lattice, "B" rating would resist a 6"x 6" lattice and "C" rating would resist a 2"x2" lattice.

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Asphalt is derived from crude oil and is actually what remains after the "good stuff" is extracted during the refining process. It has been chemically characterized and probably contains over 200 different chemical compounds.

Coal tar is derived from coke, used in the basic steel making process.

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Yes. Asphalt is readily soluble in a petroleum distillate such as kerosene, gasoline or mineral spirits. (This is logical since asphalt is derived from crude oil, as are these solvents.) Coal tar is not soluble in these organic solvents.

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Red rust is the iron oxide corrosion product that comes from ferrous metal (read: steel) as a result of weathering. This can be exacerbated by acid rain and corrosive environments, such as strong chemical and salty sea side environments. "White rust" refers to aluminum or zinc oxides that form as result of corrosion.

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Red rust is very loosely adherent to the metal substrate. As such, it does not provide a suitable substrate for coating adhesion. However, white rust, either as zinc oxide or aluminum oxide, is very tenacious or is usually well adherent to the existing substrate and do not need to be removed. However, the roof should be thoroughly cleaned to remove dirt.

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EPDM like most rubber chemistries give the best performance (durability, elastomeric properties, anti-aging, etc) when they contain carbon black as an ingredient. Unfortunately, carbon black (as the name implies) comes only in black color.

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The mica dusting is an anti blocking or release agent that is required for processing of the rubber. During manufacture, the EPDM is vulcanized (like a tire) in a batch process. Here the uncured EPDM is rolled up into a long roll and placed in an autoclave, where under heat and pressure, the EPDM is converted from a plastic to a rubbery material. If there was no release agent on the rubber, it would be impossible to unroll the membrane.

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Weight solids is a measure of the "weight percent" of the roof coating in the can. It is an arithmetic computation, of a simple laboratory test, where a sample of the coating is accurately weighed and placed in an oven and the liquid is allowed to evaporate. The sample is reweighed. The weight of the dried sample is divided by the weight of the wet sample and described as a percentage. Hence if a 10.0 gram sample of wet coating is dried in an oven and reweighed if the dry weight is 5.0 grams, the coating is 50% weight solids. This provides some indicator about the amount of quality in the can. The specification for weight solids will aid the purchaser in determining how much value there is in the can.

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Volume solids is similar to weight solids, and is even more useful as a measure of quality than weight solids. Simply described, if a coating has 50% volume solids, then a 5 gallon container of coating would be exactly half full when all the liquid has evaporated. This metric is a bit more difficult to determine experimentally, but is much more useful. It can also be determined mathematically knowing some key parameters of the raw ingredients. Since coating applications are often specified by dry film thickness, knowing the volume solids will insure proper dry film thickness. Suppose 20 wet mils of coating are applied and measured using a wet film thickness gauge. If the volume solids are 50%, this would yield a dry film thickness of 10 dry mils.

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There are many possible causes for air entrained in applied roof coating... One may be air that became entrained in the coating during manufacture, shipping or on-site mixing. Most roof coatings contain some components called defoamers that are designed to reduce the amount of air entrapped in the wet coating during manufacture.
On-site mixing may actually whip air into the coating. Another source for air entrainment occurs when the coating is rolled onto a roof. If the coating is rolled "aggressively", then air can also be whipped into the coating. A third source is when the coating is applied using an airless sprayer. If the draw side of the pump has a small leak, air can be sucked into the coating stream as it enters the pump. Since the coating is viscous and is under suction at this point, no coating will seep out of the plumbing connection.

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Yes. Air entrainment is very detrimental to coating performance. Coating specifications listed in product data sheets are based on the performance of a coating film that is free of air voids. Since air voids do not block UV radiation from the sun, and have no mechanical or water barrier properties, the properties predicted by the data sheet will not be realized. The coating will not block the UV portion of the sunlight or block water intrusion or tolerate expansion and contraction as well as an air void free membrane.

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The term polyurethane describes a general chemical type. However, within this general type there are actually two sub classes; one is aromatic polyurethane and the other is aliphatic polyurethane. The aromatic polyurethanes are not durable and are easily attacked by sunlight. By contrast, the aliphatic polyurethanes are very durable. Sprayed polyurethane foam is made from aromatic polyurethane and therefore must be coated.

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No. What you have observed is foam that is "off ratio". Sprayed polyurethane foam is manufactured by mixing 2 components, A and B, at equal proportions. If the proportions are incorrect, the foam can have the appearance you describe. What you've described is characteristic of off ratio form where the A component is greater than the B component.

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This foam structure is dull looking, with irregular cell structure and is much softer feeling than normal equally proportioned foam.

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The surface smoothness will have a direct impact on the amount of coating needed. If the surface is smooth or has what is described as an orange peel textures it is suitable for coating. Also its smoothness will make coating an easy process. As the surface roughness increases to verge of popcorn and ultimately "tree bark", the roughness increases and it becomes more difficult to get the required amount of dry film milage on the entire exposed surface of the foam.

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If the tests were conducted in accordance with ASTM D-6083, then the samples should have been prepared at 20 dry mil thickness. Obviously the results of these tests will be somewhat different if the same product were tested at 20 versus 30 dry mils.

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Sometimes, yes. Our experience has shown that the adhesion values actually increase with weathering. This is because the coating, which contains some low levels of water sensitive components necessary to maintain stability in the can, leach out when exposed to the rain. These water sensitive components have a slightly negative effect on adhesion. With them removed from the coating, and specifically at the coating/substrate interface, the adhesion values increase.

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The sand is a "release agent" to prevent against the roll sticking together while it is rolled up. This is sometimes called "blocking". It's the same reason EPDM has mica or other dusting agents on the membrane.

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This is a release agent that is applied to the uncured EPDM during manufacture and just prior to vulcanization. After vulcanization, the roll is unrolled prior to final packaging and shipping. If the release agent were not applied, during vulcanization the roll would become one very long and large "tootsie roll", and would be unsuitable for use in roofing.

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Yes. Release agents can interfere with adhesion. Since they are not embedded into the membrane, the coating adhesion will not be as good as it would if the release agents had been removed prior coating.

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Adhesion is best described as "an interfacial property". That is, the quality of adhesion has as much to do with the coating or adhesive as it does with the substrate. Think about applying an epoxy adhesive to a TeflonR frying pan. Chances are the adhesive will not adhere well. Why is that? Is it because the epoxy is not a good adhesive, or because the Teflon surface of the fry pan is not clean? No. It is because the adhesive is not "good", but rather, given the chemistry of the substrate and the chemistry of the adhesive (coating) are not suitable or compatible for each other.

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Some modified bitumen actually have a very thin coating of a dried soap film on the surface. This is applied in the factory while the membrane is still hot. The membrane is immersed in a water bath where soap has been dissolved. The bath cools the membrane prior to final roll-up and packaging, and the soap film prevents blocking. HOWEVER, since the soap film is invisible, if a water borne coating is applied, it may not adhere well. (Think of it as applying a coating to a bar of soap and, after drying, allowing it to get wet.) Coatings do not adhere well to soap.

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This is a difficult question to answer. Much depends on the product, roof slope weather and rainfall conditions and equally on the location where the roof is located.

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Yes. Based on research conducted by Dr. Hashem Akbari and his associates at the Lawrence Berkeley Laboratory, they would predict that the long term solar reflectance, barring any anomalous microclimatic effects, is 80% of the original solar reflectance value. If the initial value was 83% the long term expected value would be 66%.

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Dead load refers to the weight of the roof and roof mounted equipment that are permanently placed on the roof deck. This would include the weight of the insulation, roof membrane, recover roof, aggregate, coating, HVAC units, satellite dishes and other antennas, and cooling towers. Live load refers to the weight of temporary "stuff" that may be on a roof such as rain water in ponds or snow or ice buildup.

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If a typical acrylic roof coating having weight solids of 67%, at 12.0 pounds per gallon, were applied at 3 gallons per square, it would add 24 pounds per square to the weight of the roof. So the weight would increase by 0.24 lbs per square foot. If a scrim were imbedded into the coating, that would also be factored in.

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Yes. Acrylic coatings are water-based and susceptible to bacteria and fungal growth both in packaged storage and later as a dry installed coating. To ensure storage stability and film integrity in the field, NCC uses appropriate “salt and pepper” mildewcides and algaecides in our quality coatings. We also use Zinc Oxide in our products. Zinc Oxide resists mildew and algae growth and unlike other coating mildewcides, does not leach out of the dried coating film or get destroyed by continued exposure to UV rays. It also provides opaqueness to UV, whiteness and reflectivity to a well-formulated acrylic coating. Various leading biocides are also used in order to balance these additives with ZnO to achieve the best in-can and dry coating preservation possible. Using the test method ASTM G-21, our products receive a zero rating (no mildew growth).

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Urethanes: 

- Usually solvent borne.

- Expensive versus acrylics.

- Aromatic urethanes are not durable and must be coated with an aliphatic urethane.

- Lower elongation than acrylics.

- Higher tensile strength than acrylics.

- Can be one part or two parts (need to mix coating with catalyst before applying)

 

Acrylics:

- Can be water or solvent borne.

- Better cost/performance than urethanes.

- Higher elongation than urethanes.

- Usually lower tensile strength than urethanes.

However:
NCC's AcryShield A550 has some of the better properties, like higher tensile strength, that are usually associated with expensive solvent borne urethanes, but from a one component water borne acrylic.