Commercial Roofing Spray Applied Polyurethane

Roofing Companies December 22, 2022 Share
Commercial Roofing Spray Applied Polyurethane

What is spray applied polyurethane commercial roofing? 

     Spray applied polyurethane roofing products are most commonly known as a quick drying and appealing commercial roofing maintenance product.  These are the materials used in the manufacture of commercial or industrial-type coatings such as those found under carports, garages and warehouses are still fairly new to the market. Unlike traditional architectural coatings, these products come with an array of unique benefits that make them ideal for a variety of different applications.

  One of the newest developments in this industry is that of spray-applied urethane, which has quickly become a popular choice among contractors and building owners alike. This particular coating is designed to protect asphalt shingles from sunlight, rain and hail damage. It provides protection for as long as 20 years, so you can be sure it will be working hard on your project for quite some time. You’ll often find these types of roofs on new construction sites or on buildings undergoing major reconstruction projects since they provide a superior form of insulation.

  To understand how commercial roof coatings work, it’s important to get an overall understanding of how shingles are made. The raw materials used include recycled rubber tires, plastic (typically polyester) and asphalt, which is a non-petroleum based petroleum byproduct. These products are mixed together with a catalyst that speeds up the process of turning them into what we commonly known as shingles.

   Commercial roofing manufacturers use several different types of polymer binders to put their coatings together, but urethane is often the most popular choice because it produces a number of long lasting benefits that can be applied to many different situations.

  After the base coating has been installed, it will be allowed to dry thoroughly before being topped off with additional layers designed for extra durability and protection against everything from UV rays to water damage.

What You Need To Know About How To Apply Commercial Roofing, Urethane Coating (SPF) Spray Polyurethane Foam. 

  1. Power spraying an elastomeric chemical based material that will cure upon air drying. This can be done with a spray on gun. Just like the one used at home improvement stores. The difference in quality and type of material is extreme.
  2. Applying elastomeric coatings with a brush or roller which dry to a tack free stage but have longer curing times between coats due to different chemistry than number 1 above.
  3. Urethane coatings are water-based, latex, solvent base or epoxy, they can be rubbed out smooth depending on application and substrate choice. They are all applied in multiple coats using masking and high build practices. They are installed over a clean, dry surface free of contaminants and have a low odor.
  4. Part A,B one part or two part is not specified however they can be mixed together with an average shelf life span of 6 to 8 months. The hardener can be compromised by moisture so the container should be sealed after using the hardener up. To extend its life place it in a freezer compartment with little air flow for long storage periods under proper conditions there are many other ways to save unused amounts like adding it to another gun that has been used up or cleaning up your brush with some remaining material before throwing it away and so on. You’ll always want to buy extra as you will run out due to mistakes made from not being accustomed to using the material, running low on material for any length of time, etc.

How to coat a commercial roof with polyurethane 

  Inspect the surface and remove all dirt, loose paper or dead bugs before applying coating. On low slope roofs use a pallet knife and rollers especially when working in hot weather temperatures under 90 degrees F (32C). If an elastomeric material is going to be installed over metal surfaces it must be scuff sanded first. This should only be done by qualified installers who regularly work with solvent based elastomerics as they are very flammable materials that can emit harmful vapors.

   The first coat is applied at 60 mils dry thickness and screed with a plastic straight edge, (not steel as it can leave a metal mark). The next coat will be 45 to 50 mils in thickness. Let the film cure for 7 to 10 days minimum before proceeding. The chemical nature of urethane makes it prone to rapid degradation from sunlight, temperature extremes and moisture absorption. This should not deter you from using this product as many excellent roof systems have been achieved over the years.

How much does one gallon of roofing polyurethane coating cost? 

   It really depends on where you buy it from and who is working with it. Coatings are worth so much per hour spent on them therefore some labor costs may lower your price point depending on job conditions. At other times the cost may be as high as $110 per gallon or more.

How long does it take to apply polyurethane roofing coating? 

  This is dependent on the crew and their experience level but a low slope roof could easily be done in 1 day using two men applying materials with 3 to 4 guns going at once. A large flat roof would require approximately one man for every 2,000 sf area and double that if there are skylights involved which can be treacherous due to heat stress issues that crews must work around as they will have molten material dripping down on them from above while working on top of the structure being coated. It depends on underlayment, heat reflectors, tightness of seams and structure size also how much work is performed on the inside of the building and a lot of other variables.

What is the normal warranty for polyurethane roofing installation? 

  15 to 20 years depending on substrate, film build up thickness and application quality. The material’s shelf life is in excess of 10 years

Are there any Pre-coat requirements for polyurethane roofing products? 

  For metal roofing as well as flat or low sloped roofs it is best to apply two coats with a clear top coat after all structural commercial roofing maintenance repairs are made. Before going back over with urethane for another coating, it should usually be applied when there is an average temperature range of 45 degrees F and above (7C). Before that you will want to avoid getting the surface wet resembling rain or sunlight for at least 24 hours until the original first layer has dried out completely but this does not mean you can’t go back with urethane sooner it’s just not recommended. When a pre-coat is applied the material has to cure for at least 7 days before going back with another coat, and if there is any curing shrinkage on the substrate it will be in this time period after the first top coat application that this happens. This is why many contractors apply two coats of clear so that they have some flexibility to work around this as well as giving them more room for error when additional coats are applied down the road at a later date.

Are there any types of Pre-coat safety concerns when working with polyurethane roofing coating?

  Work should be performed in temperatures under 90 degrees F (32C) and kept below 75 degrees F (24C) when applying or removing films from hot surfaces. Any melting that occurs on the job should not be allowed to drip or run onto any material or surface underneath as it may discolor, blister or burn the substrate below if they get too close. Always use gloves and eye protection when applying anything over 90 degrees F (32C).

Is it necessary to prime before applying polyurethane roofing coatings? 

  No, primers are not necessary but we recommend you seal all non-primed metal roofs with a rubberized underlayment before applying urethane coatings for added performance safety factors as well as UV protection during film curing periods in direct sunlight which will expedite drying times by providing a protective barrier between the wood fibers of plywood sub-floors and wooden roof framing materials. Please note—Plywood sub-floors that are coated in the U.S with water-born products such as latex paints or linseed oil do not require an extra primer application.

Is it better to Spray vs Roll polyurethane roofing coatings? 

  There is a lot of different schools of thought on this subject but I would say if you can spray it than please do, urethane coatings for roofs have much higher performance characteristics when applied using one of our automated machines because it eliminates human error which could damage the substrate below and create hundreds or thousands more in repair costs to obtain similar results visually by other means. Even though almost all roll-on applications: A) Tend to look like a roller was used instead of a spray gun B) Are less flexible and cost operators their jobs due to the high U.C.F.(scrap rate) in the field C) Are more labor intensive and sometimes less effective depending on underlayment types and quality.

What is the Spray Performance of polyurethane roof coatings? 

  Very long lasting with extremely low wear rates, PVA’s (polyvinyl alcohols) are inert by themselves but when hardened will not degrade or oxidize and have a very tough durable shell that makes it resistant to UV damage as well as heat stress cracking if used correctly which means you will get the best performance from this material if applied using one of our automated machines to achieve maximum adhesion possible. Primers are not necessary for urethane coatings for roofs unless there is an ammonia release present at humidities over 75% or if water is falling on the substrate under the roof because it will break down urethane over time, this is why some contractors skip primers altogether to save themselves a lot of money in materials and labor.

How long does PVA Polyurethane Coatings Typically Last? 

  Under normal conditions: 5-10 years before recoating is necessary depending upon usage patterns and exposure to environmental extremes such as direct sunlight and heat stress cracking

Can you apply polyurethane coatings if the roof has old coatings on it still? 

  Yes, but we do not recommend that you attempt anything that could be classified as unusual or non-standard installations unless you have experience with all types of building systems, this includes maintenance coating removal techniques for various roofing substrates when performed improperly can lead to catastrophic failures in the future if not done properly.

Do you have to heat cure PVA’s? 

  Yes, but usually for at least 24 hours before allowing walking on it or driving vehicles over it with load capacities of more than 25 tons per axle. The maximum curing period that we recommend is two weeks depending upon ambient conditions such as direct sunlight and water run-off while in use during application to achieve long life performance characteristics from our coatings.

What colors can I get polyurethane roof coatings in? 

  They manufacture materials in almost any color you want for a roof coating using EPDM rubber binders which means there are no regulations on what pigments and metal flakes can be used so they can be blended together in a way that will give you the best possible results depending on the environment that you are operating in.  Environment is usually a commercial roof, but could also be on a home as well.

 What about Temperature Ranges Needed to apply polyurethane roofing coatings? 

  The PVA’s have an extremely broad range of operating temperatures that vary between a temperature of -40 degrees F to 180 degrees F but this is not what they recommend for most jobs because some substrates will begin to flex or warp over time which could lead to future roof system problems with roofs especially when there are multiple layers of materials present, installing urethane coatings in areas where their use has never been done before is just plain unprofessional and is very risky in the long run.

What are interesting facts about the application of polyurethane roofing coatings? 

  That’s easy, we do not suggest that any system be laid over existing coatings of any type unless you are going to remove all traces of previous products using a product called ‘Safe Strip’ for surface preparation which will remove all traces of old coatings and even some stains if used on them as recommended by the manufacturer (Do NOT substitute another brand or use anything without sanding first!). The reason that urethane coatings do not adhere very well to other buoys is because there was a reaction between the two different polymers; over time this weakens both materials so we only recommend that non-urethane topcoats should never be used on ANY urethane system.

Is there a problem with EPDM? 

  No, but there is not a lot of information available on the internet about using it for roofing projects so we do not recommend that you use this material unless you are an expert in all types of rubber coatings because they have very different properties than those used in other areas such as flat roofing systems. This includes working on hot substrates and flaming during application which requires special precautions to be taken if it has been installed properly by our technicians before arriving at your job site

What type of drying blankets should I use to help cure polyurethane roofing coatings? 

  The best thing that we have found that will give you the highest quality workmanship is ‘Pacific Drying Systems’ products with the ‘PDS heater dryer’ but if you use a lower quality version do not expect to get the same results. This company is located in San Francisco and they have been making advanced products for years so we highly recommend that you contact them to find out what type of drying blanket work best for your project because this depends on the substrate that is being used for your roofing system.

Do I need aluminum plates or foil for this process? 

  Yes, it’s imperative that these are used during rolling and brushing along with other techniques such as using pieces of carpet foam padding cut into 1/2 inch thick pads which help prevent marring on low pressure coatings or systems that are installed over existing materials.

How long it should take for a polyurethane coated roofing system to cure? 

  Preparing the substrate has always been the most important thing that contractors need to be concerned with because this includes adhering all seams / joints properly using non-metallic compatible sealants like ‘DAP Polyurethane Construction Sealant‘ which comes in white, gray, and black. All seams/joints must be sealed before applying any coating. Some of these materials have very strong solvents which could soften or melt your joints if you do not prep the area properly by sealing all surfaces especially around air conditioning units, drain outlets and anywhere else where an opening penetrates through the sub-roofing system. This means that you will need to use ‘DAP Touch ‘N Foam‘ for all areas with a decent gap. It comes in Orange color, so you’ll want to make sure you go over that with the polyurethane roof coating. Now we will move on to prepping surfaces:

What type of preparation should be done before applying polyurethane roofing coating? 

  This is very important because a lot of contractors think that they need to sand their roofs but if you do this without using gels then over time a white powder will start to accumulate on all areas around your edges leading to an unsightly appearance, it could cause your coating system to fail prematurely too. They are available at all hvac supply stores and are very cost effective.

How important is the polyurethane primer to get a good looking finish after applying to a commercial roof? 

  It’s just as important on urethane smocks as it is with flat roofing coatings because the ‘Rust-Oleum Professional’ brand along with others like PPG, Sherwin Williams, Tremco etc… (that have been sold over the years) can often times cause bubbles or streaks when they dry because of various reasons. The bubbling will warp your paint if this happens and in some instances it could even peel off which means that you need to have a competent crew that knows how to apply materials properly so do not use products unless you know for sure that they work well.  Check out this great material idea for your commercial building: Commercial Rubber Roofing Products


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