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Frequently Asked Questions

Q: What are “Cool Roof Coatings”?

A: Please refer to this guide.

Q: Why choose Lucas roof coatings??

A: Please refer to this guide.

Q: What are the spray application recommendations for Lucas Coatings?

A: Please refer to this guide.

Q: Which are better, solvent, water-based or moisture cure elastomeric coatings?

A: Solvent, water-based and moisture cure coatings each have their advantages.

Solvent based tend to be more waterproof, can be used in colder weather, won’t freeze, are less affected by humidity and rain after application and will adhere to certain surfaces, such as TPO, that water-based coatings often will not.

Water based coatings are lower odor, are “breathable” so are more suitable for masonry, are less prone to “bleed through” or discoloration when applied over asphalt and are generally easier to spray as they don’t change viscosity significantly at different temperatures

Moisture cure coatings allow solids of up to 100% so the film thickness per applied volume is greater. They are generally low odor and low VOC.  The tradeoffs are shorter shelf life and limited adhesion to some surfaces including TPO and asphalt that require primers.  While they wont freeze, moisture cure coatings will not cure normally when temperatures are below freezing and there is little free moisture in the air.

Q: What is the Dew Point and why is it important?

The dew point is the point at which moisture in the air condenses into liquid water. Many Lucas coatings require a dry surface. Surfaces may appear dry but moisture will condense as the coating is applied because the application of coating will often lower the surface temperature of the roof surface at the point of application causing liquid water droplets to be trapped under or encapsulated in the coating. Please refer to this table for more information:

Dew Point Chart.

Or for a more specific determination use this free calculator: http://einstein.atmos.colostate.edu/~mcnoldy/Humidity.html

Q: What are reflectivity and emissivity and why are they important?

A: reflectivity is the percentage of solar energy reflected by the coating back into the atmosphere. The remaining energy that is absorbed increases the temperature of the roof surface. Higher reflectivity results in less absorbed energy which results in less potential heat gain.

Emissivity is a measure of the coatings ability to emit absorbed solar energy as infrared radiation. higher emissivity will generally result in a cooler surface for two materials with the same reflectivity. The relationship between emissivity and roof temperature is complicated by factors such as conductivity of the roof surface and wind speed that will allow some lower emissivity surfaces to shed heat energy more efficiently.

Q: What type of coating is more energy efficient, black, aluminum or white?

A: The answer depends upon climate and the percentage of energy used heating and cooling a structure. In hot climates white is most efficient, in temperate climates aluminum coatings with high reflectivity and lower emissivity yield the best result. In extreme Northern regions dark colored roofs will save the most energy as air-conditioning is uncommon.

Q: What’s the difference between asphalt and coal tar?

A: Asphalt is derived from crude petroleum. It’s an aliphatic or ‘straight-chain’ hydrocarbon resin. Coal tar is derived from the destructive distillation or coal. It is an aromatic ‘ring shaped’ hydrocarbon resin. The two are different and generally incompatible. Asphalt is normally lower in cost, can be used on pitched roofs to vertical, has fair resistance to UV degradation and can be left bare or surfaced in a variety of manners, but it has poor resistance to ‘ponding’ water. Coal Tar can only be used on near to dead level roofs and has poor resistance to UV degradation so it must always be surfaced with a layer of gravel, pavers or vegetation. Coal tar has good resistance to ponding water and exhibits ‘cold flow’ or ‘self-healing’ characteristics.

Q: How do I tell the difference?

A: There are a number of indications as to the type of built up roof. The first is that coal tar is always surfaced with gravel, pavers or vegetation. If it,s bare, coated or surfaced with sprayed in granules, it’s asphalt. If it is a gravel roof the simplest method to determine the type of roof is to wipe the roof with a clean rag soaked in mineral spirits paint thinner. Mineral spirits is an aliphatic solvent and is only capable of dissolving asphalt, which is aliphatic as well. Asphalt roofs will leave a black or dark brown residue on the cloth while coal tar will leave a yellow or slightly green residue. Several passes with a clean cloth may be necessary if the roof is dirty.

Q: What allows wet surface roof cements to adhere to wet or under water surfaces?

A: An oil soluble ‘surfactant’ or soap is added to the mastic. The surfactant lowers the surface tension of the mastic and allow the moisture present on the roof to be displaced. Pressure will be necessary to aid in adhesion of the mastic to wet surfaces. These surfactants also promote penetration of, and adhesion to, polyester reinforcing fabrics.

Q: Aren’t all asphalt roof cements the same?

No, some manufacturers add large amounts of filler, reclaimed fuel oil (usually listed as petroleum distillate) and even up to 20% water! Fillers not only increase the sheer weight of the material but can also reduce long term performance. Some commercially available roof cements weigh in excess of 12 lbs. per gallon (60 lbs per 5 gallon pail). In contrast, Lucas Roof Cements weigh 8.3 to 8.5 lbs. per gallon (42 to 45 lbs. Per 5 gallon pail).

Q: What’s the difference between Lucas ‘Standard Grade’ and ‘Premium Grade’ cements and coatings?

A: Lucas Premium Grade roof cements and coatings are manufactured from higher softening point asphalts which causes them to cure faster, age more slowly, and resist oxididative cracking or ‘alligatoring’. Lucas Premium roof coatings can take roof traffic sooner and Lucas Premium roof cements will adhere to vertical surfaces without sagging, even when hot mopped. Lastly, Lucas Premium roof cements contain no unnecessary fillers like limestone dust (calcium carbonate), kaolin clay or slate flour. These fillers not only increase the sheer weight of the material but can also reduce long term performance.

Q: How should I evaluate the relative quality of different aluminum roof coatings?

A: Unfortunately there is no clear standard beyond the minimum requirements of ASTM D-2824, which all Lucas Aluminum Coatings meet. The reputation of the manufacturer is paramount. The simplest method to sort out aluminum coating is by aluminum pigment content. Some people object to this standard by claiming that a coating with 2 lbs. of ground up aluminum cans would rate the same as a coating with 2 lbs. Of high quality leafing aluminum paste. For this reason we recommend that users ensure that, when aluminum coatings are graded by pigment weight, the aluminum paste is quoted as meeting ASTM D-962 type 2 — Specification for Aluminum Powder and Paste Pigments for Paints. Another excellent source of information is the EPA’s Energy Star Program which lists reflectivity values of various roofing materials.

Q: When should aluminum roof coating be applied to a new asphalt or modified bitumen roof? As soon as possible or after the roof has cured?

A: The best time to apply aluminum roof coating to a new built up roof is after the roof has fully cured. This will take at least 6 weeks. Application of aluminum roof coating to uncured asphalt will likely result in sulfur and oil bleed through and sometimes severe cracking or splitting.

SBS modified bitumen should be coated as soon as practical.

APP modified bitumen is the most challenging roof to coat with aluminum roof coating. Applying the coating immediately will reduce ‘exudation’ or bleed through, but it will not be eliminated, expect temporary discoloration. Waiting until the membrane has cured will allow most of the exudate to bleed out. If the roof has positive drainage the exudate will wash off the roof and the modified bitumen will present a clean and stable substrate. Roofs with ‘bird baths’ may retain exuded oil and sulfur compounds in low areas. This retained contamination will interfere with adhesion, discolor the coating and can cause the coating to crack. This contamination should be removed with a suitable power washer and detergent. It is the prerogative of the roofing contractor to examine the conditions present on a particular roof and choose the appropriate action. If there is any doubt please contact our technical personnel.

Q: Are all ‘rubberized’ roof cements ‘elastomeric’?

A: Not necessarily. Rubberized means that ‘rubber’ has been added to the mix. Elastomeric implies that the material has the rubber like properties of elongation and recovery. Some ‘rubbers’ such as butyl, neoprene and SBR will not impart elastomeric qualities on an asphalt mixture. ‘Rubbers’ such as SBS and SEBS will, but only if added in sufficient quantities to an asphalt that is suitable and not overly corrupted with economizing fillers.

Q: What is the difference between ‘waterproofing’ and ‘damproofing’?

A: Damproofing will resist penetration of moisture through a foundation into the interior under normal conditions. Waterproofing will do the same even in the presence of hydrostatic pressure.

Q: What are the advantages and disadvantages of applying coatings by brush, roller and spray?

A: Brush application allows the coating to be ‘worked in’ to the surface. This will ensure an adequate bond, particularly if the surface is less than ideally clean and smooth. Brush application is the most time consuming method and will often result in visible brush marks.

Rollers are faster than brushes and still allow a measure of mechanical assistance in adhesion to the surface. Rollers also eliminate brush marks but may still leave a textured surface. Applicators should be aware that rollers will lower the natural rate of coverage below that which is recommended.

Spray application is the fastest method of coatings application and generally leaves the smoothest surface. Total lack of mechanical assistance in adhesion, difficulty in assessing coverage rates and the danger of ‘over-spray’ limit the suitability spray applications.

Q: What is the difference between ‘waterproofing’ and ‘damproofing’?

A: Damproofing will resist penetration of moisture through a foundation into the interior under normal conditions. Waterproofing will do the same even in the presence of hydrostatic pressure.

Q: What is the difference between silanes, siloxanes and silicone?

A: All three are silicon based molecules that have masonry waterproofing applications. Silanes are monomers, the smallest and most simple of the three molecules. Silanes are best suited for dense surfaces like concrete and cultured stone. High concentrations of about 40% are necessary because of silane’s volatility.

Siloxanes oligomers are larger and more complex molecules than silanes. At lower concentrations they provide excellent moisture protection to more porous surfaces like split face concrete block. Siloxanes can be blended with silanes to produce a treatment with the advantages of both materials.

Silicone polymers are large functional molecules that are used in caulks and sealants. Silicones can be useful for protecting porous natural stone that has a neutral ph. For concrete and masonry applications, silanes and siloxanes penetrate farther and preserve the surface’s original appearance.

Q: What type of insulation is suitable for below grade foundation walls.

A: Extruded polystyrene and rigid fiberglass are the two most suitable types of insulation. Polystyrene is inexpensive and widely available. However, polystyrene does not allow water to drain down to the drain tile, is incompatible with solvent based systems and is not recommended for use in areas where termites are found because it provides a protected rout from the earth to the wooden structure.

Rigid fiberglass is the most suitable type of insulation for below grade foundations. It is resistant to decay, will not harbor pests and sheds water efficiently to the drain tile.

Q: Is an ICC Evaluation report required for polymer modified asphalt waterproofing?

A: No, a research report is not required for polymer modified asphalt waterproofing provided it is applied at a minimum thickness of 40 dry mils. 40 mils of polymer modified asphalt is an ICC “approved method” for complying with IRC 406.2. Only unapproved methods require a research report.

Q: What is the difference between a “masonry paint” and a “waterproof masonry coating”?

A: Masonry “paints” are intended as decorative finishes for masonry walls. Waterproof masonry coatings are performance coating systems that offer breathable moisture protection and crack bridging abilities in addition to decoration.

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