This is by far the best article I have read on roof care:
Keep in mind that your roof does NOT have to look like an operating room at the hospital! It functions quite well with a few spots or a pluthera of stains!
From "mydrv.net" One of the better articles I've ever found regarding EDPM and TPO roofing!
"This article will focus on two types of roofing materials – EPDM and TPO. The two leading distributors of these rubber roof systems are Dicor Corporation and Alpha Systems, both located in Elkhart, Indiana.
EPDM stands for Ethylene Propylene Diene Monomer. This type of rubber roofing membrane is made to last 20 years and has a 10 to 12 year guarantee, depending on the brand. EPDM is one of the most versatile and long lasting materials ever manufactured for outdoor exposure. Most RV industry experts consider EPDM the most dependable, most cost effective and easiest to maintain roofing material. EPDM is described as “ideal for outdoor applications because of its excellent resistance to ultra-violet light, ozone, oxidants and severe weather conditions”. EPDM roofing membrane oxidizes slowly. In a dozen years it may only oxidize 10% of its thickness. This oxidation is what causes the white-gray or gray streaks that run down the sides of RV’s – especially in heavy dew or light rain. EPDM also becomes very slippery when wet.
TPO – Thermal Poly Olefin – was introduced to the RV and Marine Industries in 1994. It is resistant to algae, mold, fungus, and other biological agents. The chemistry of TPO allows for no chalk residue or degradation of the membrane through its useful life. The TPO membranes are non-skid when wet and therefore are used frequently as floor covering in the pontoon boat industry as well. The chemical additives used in TPO for protection from UV light are not self-sacrificing. Instead, they operate in a regenerative fashion as they interfere with the degradation reactions that occur from UV light exposure. Some features of TPO are the advanced polymer technology, weight reduction and easy installation due to its soft and pliable nature. TPO carriers a 12 year manufacturers’ warranty.
There are different opinions when it comes to cleaning and protecting rubber roofs, but everyone agrees that EPDM’s solvent and oil resistance is poor. Care and maintenance instructions from both manufacturers have the following warning: “DO NOT use cleaners or conditioners containing petroleum solvents, harsh abrasives or Citric based cleaners. You may cause irreparable damage to your roof”
The percentage of petroleum distillates doesn’t matter. THERE IS NO LEVEL OF PETROLEUM DISTILLATES THAT IS RECOMMENDED. Laboratory tests conducted evaluated the effect of a leading RV ‘roof treatment’ product on EPDM roofing membrane using standard sunlamp and immersion testing procedures. The ‘roof treatment’, which contained petroleum distillates, caused a 63% mass change (swelling). Petroleum distillates soak in and cause the adhesive to loosen and the membrane to balloon. Then, when the ballooning goes down, the rubber roof may never again adhere properly or completely. Don’t be fooled by names such as “organic solvent”, “hydrocarbon carrier”, etc. Petroleum distillates by any name should NEVER be applied to EPDM. If you aren’t sure about a product, contact the manufacturer and request a copy of the Material Safety Data Sheet (MSDS). Look under the section entitled “Hazardous Ingredients”. If it lists any petroleum distillates, do not use it on EPDM.
To maintain your warranty, all that is required is periodic cleaning at least 3 to 4 times per year. What you use is wide open as long as it does not contain petroleum distillates, harsh abrasives, or delaminane (citrus based cleaners). Dicor recommends a non-abrasive type cleaner such as RC 100TM, Borax or DawnTM and a medium to stiff brush. Alpha Systems recommends using a household cleaner such as CometTM, Spic-N-SpanTM, Ajax TM, etc. They say to use a medium-bristled scrub brush in place of a sponge because the EPDM rubber roofing material is not smooth like fiberglass. For more stubborn stains, i.e. oak leaves, pine sap, mold or mildew, the use of a kitchen cleanser with bleach, such as TilexTM or Soft ScrubTM can help. Monoethalomine is also very effective, non-abrasive and minimizes the effort in removing oxidation, pitch, sap, mold and mildew, as well as berry stains from birds and trees. A quick rinse with chlorine (bleach) is necessary to kill the mildew spores and retard their regrowth. Caution should be exercised when washing your roof to prevent cleaners from running down the sides since this could cause streaking. Always pre rinse your RV sides before you rinse your roof. On TPO roofing, Alpha Systems suggests using Murphy’s Oil SoapTM with a soft nylon brush or sponge. DO NOT USE SOLID OR GRANULATED CLEANERS on TPO, AS THEY WILL MAR THE NATURAL FINISH. A good thorough cleaning with some elbow grease, along with the oil soap should keep your roof looking good and remove most stains. Again, any non-granulated, non-abrasive cleaner may be used as long as it does not contain petroleum distillates or delaminane (citrus).
Protecting rubber roofs is s topic of great debate. Per Dicor’s web site, “the guarantee does not require the use of any protective ‘roof treatment’ or ‘roof protector’ product and recommends only cleaning”. This is consistent with both Dicor and Alpha Systems. However, Dicor states that when the roof no longer looks good to “clean the area and treat it with a product that will repel soiling and is safe for EPDM”. Both Dicor and Alpha Systems stated that they have never had issue with any protectant provided that it contained NO PETROLEUM DISTILLATES."
