BUTYL LIQUID RUBBER – EPDM COATING CORP
Don’t re-roof. Re-coat and save thousands of dollars
Properly applied roof coating systems can breathe new life into a mature low slope roofing system, brightening its appearance, enhancing its energy efficiency and delaying for years the day when it will have to be recovered or replaced. The operative phrase in that sentence is “properly applied.” Coating a roof is more than simply spraying, rolling or brushing on the finish coats. What will determine the quality and longevity of the installation is the time and attention paid to preparing the roof before it is coated. Too often, contractors take shortcuts on, or skip altogether, this essential first step. The result? Problems with the existing roofing system remain problematic, the coating system does not properly adhere to the substrate, and a roof restoration that could have lasted 10 or 20 years fails in as little as two or three. Completing three simple steps before applying the coating system will prevent this outcome and help ensure the newly coated roof delivers the expected years of hassle-free, watertight performance. First, repair any existing damage. Second, perform the roof surface.
WHY PREPARATION IS ESSENTIAL
It is understandable that contractors new to coating application and untrained in the process could overlook the preparation step. Their experience is in working with roll-good roofing, where preparation is a step that can be overlooked because the existing roof will be recovered or replaced with new TPO, EPDM, PVC or modified bitumen. The new system will cover up any leaks or other damage and will be designed to address ponding water or other issues that plagued the existing roof. When coating, however, the contractor is not installing a new roof, but is restoring or maintaining the performance of the existing roofing system. Roof coatings are not “miracles in a bucket.” They will not fix leaks, reseal open seams, repair deteriorated flashings or loose terminations, prevent ponding water, address damaged or saturated insulation or substrates, or correct other problems with the underlying roofing system. Those issues will still exist after the coating has been applied and may prevent the coating from properly adhering to the roof. And if a coating is slapped on top of a grimy, greasy, debris-ridden roof, it almost certainly will soon begin to flake, blister or peel off.
REPAIR EXISTING ROOF DAMAGE
Step one is to assess the existing roofing system and make necessary repairs, carefully following the relevant guidelines from the manufacturer of the original roofing system and the National Roofing Contractors Association (NRCA). In general, the existing roof assembly must be structurally sound, watertight and free of shrinkage, buckling, unacceptable ponding conditions, encapsulated moisture, open seams, open or damaged flashings, loose terminations and other serious defects. Coatings also should not be applied if the substrate or insulation is saturated with water. The good news is that, with some simple repairs, even a roofing system with significant damage can be made a viable candidate for coating. The following examples illustrate some Common scenarios. Problem: A roof has an area that is susceptible to ponding water. Solution: Fill the ponding area with slope-correcting materials or correct the slope with a cricket or tapered insulation and cover it with new materials similar to those of the existing roof. It may be necessary to install drains to allow positive drainage. Problem: A 2-square area of a 100-square TPO membrane is damaged. Solution: Cut out the problem area and replace it with like material, or heat weld two squares of new TPO over the existing membrane to recover the damaged area. Problem: There is an active leak in one corner of a roofing system. Solution: Cut into the damaged area. Remove and replace the saturated insulation if necessary. Fold the membrane back in place and flash around where the cut was made. structurally sound, apply primer to encapsulate the existing rust and inhibit the creation of additional rust. If any panels are so corroded that they are no longer structurally sound, replace them; the remaining panels can be left in place. Problem: The seam welds on a TPO or PVC roofing system are pulled or loose. Solution: Several options are available. (1) Reheat the seams to weld them back in place. (2) Put a target patch made of new membrane over the seams. (3) Reseal the seams with flashing compound.
PERFORM AN ADHESION TEST
A coating’s performance depends on how well it adheres to the substrate. An adhesion test should, therefore, be performed to ensure that the coating is compatible with the substrate and that encapsulated moisture or other underlying issues that could impact adhesion have been properly addressed. Instructions from the coating manufacturer should be followed, and those instructions may vary based on the warranty desired but following are general guidelines. Choose a 2-foot-by-2-foot area of the roof as the test site. Clean the area using a rag or bristle brush and a solvent that will flash off quickly without leaving a soapy residue behind, such as acetone, xylene or mineral spirits. Coat a 1-foot-by-1-foot section of the test area, replicating what the finished system will be. If the roof will be primed, prime the test area. Apply primer and finish coats at the same application rate that will be used to coat the entire roof. Embed several strips of Tietex or other polyester-reinforced fabric, each roughly 1 inch wide and 12 inches long, into the coating, leaving Problem: A metal roof has rusted. a 4-inch-long pull tab outside of the wet area. Brush the fabric to embed it into the coating. Apply a second coat of finish coat to ensure the fabric is fully saturated. Allow the coating to cure fully, at least 4 to 5 days. Test the adhesion using a fish scale. For each test strip, tie a knot in the loose, uncoated end of the fabric strip Hook the fish scale into the knot. Using the fishhook, pull the fabric straight up. The ideal “pull strength” is at least 4 pounds per linear inch (pli) of fabric, or at least 4 pli over a sound and dry substrate. The test is a “pass” if the fabric separates from the coating, leaving the coating still adhered to the roof membrane. The test is a ““failure”” if the coating separates completely from the roof surface. All adhesion tests should be documented with photos of the cleaned substrate, the wet coating and embedded fabric, and the face or display of the fish scale showing the resistance observed in the test.
Roof surfaces must be thoroughly cleaned prior to coating. Over years of constant exposure to the elements, dirt, oils, bird droppings and other debris collect on a roof’s surface. If not removed prior to coating, they interfere with the coating’s ability to adhere to the substrate. Rather than sticking to the roof, the coating fuses to the grime and, unsurprisingly, may soon begin to peel off. The best results will be achieved by applying the manufacturer’s recommended roof wash or cleaner and then power washing. While power washing alone will get the roof clean, the roof wash loosens the dirt, grease and other debris, allowing it to be removed with less-aggressive power washing. We highly suggest using roof protect. This cleaner actually emulsifies the contaminates on the roof and also has a built in mildewcide. This gentler approach significantly reduces the risk of damaging the roofing membrane while cleaning. Years of being subjected to sun, rain, snow, ice, heat and cold can weaken the membrane, and a blast with a heavy-duty gas-powered rig generating 2,800– 4,000 psi of pressure can easily blow a hole in it. A smaller rig generating only 1,800–2,500 psi of pressure will remove the sediment in most cases. Using a walk-behind power washer, rather than a common extension wand-type setup, also helps ensure adequate cleaning pressure at the surface of the substrate without over-exerting effort on the behalf of the worker. Rinse water should be directed toward drains and scuppers to ensure the detergent and debris are completely removed. If the rinse water is simply allowed to evaporate, what can be left behind instead of a clean, coating-ready surface is a caked-on mixture of gunk and detergent residue. EPDM roofs should be power washed twice — once with ROOF PROTECT and once with clean water. The carbon black that gives EPDM its black color breaks down over time, and that dust must be removed to ensure proper adhesion of the coating. The test of whether the carbon dust has been completely removed is a quick wipe of hand across the surface; a clean hand means a clean roof. Granulated modified bitumen roofs should be swept with a dry broom or power broom prior to power washing to remove loose granules that could clog the roof drains. Make any necessary repairs. Perform an adhesion test. Thoroughly clean the roof surface. Completing these three simple steps before coating will help ensure a successful roof restoration that extends the roofing system’s life, adding years of weathertight, hassle-free performance