How Often Should I Coat My Roof?

If you own an elastomeric coated roof (also known as a flat roof) in the Southwest part of the USA, one of the key questions that must be asked is, “How Often Should I Coat My Roof?” This is the #1 question asked of home owners to their Tucson roofing contractors in the Tucson and Green Valley areas. There are a few factors to consider that will help determine how long elastomeric roof coatings last.

When Was The Roof Last Coated?

Cool coated roofs usually need to be recoated every 4-6 years. The reasons for recoating are numerous but one of the most important is that acrylic elastomeric coatings oxidize over time. Oxidation happens when the sun dries out the microscopic top layer of the coating and it blows off in the wind or washes off in the rain. This causes the coating to thin and eventually when it thins enough the coating begins to peel and crack. If your roof has been recoated in the last 3-6 years it is best to find a good roof coating specialist to check and see how much longer the coating will last.

What Coating Was Applied to Your Roof When It Was Coated?

All coatings are not the same. Many coatings will not last more than three years before significant issues occur while other coatings can last much longer. There are variables that will effect a coating’s durability such as: was it watered down, how thick was it applied, was the roof properly cleaned before it was coated, and which coating was used? Consumer Roof Coatings has published a scientific analysis of the different type of coatings used in Arizona. Their results show the best roof coatings available and they found the top roof coating for your roof to be Tucson Rubberized 7000. We have had great luck with this coating and on an applicator’s level agree with their findings. The roof will be protected longer if the best coating is applied.

How Thick Was The Coating Applied?

Simply rolling on elastomeric coating is not enough. It must be applied in the proper thickness to sustain the brutal Arizona heat. Every manufacturer has a recommended application thickness. If this is not followed, the coating will not last as they expect it to last. This is why it is almost always best to to have your roof coating contractor apply two coats of material. It is also important that your roof coating specialist also applies each coat in the proper thickness. This is usually determined by applying the coating at a specified amount per 100 square feet. A good number for most roof coating is to apply them at 100-150 square feet per gallon of coating. Again, the manufacturer will have a recommendation that should followed.

What Substrate Was Coated?

Cool coated roofs have different substrates. Some coatings are applied directly over roof paper, some are applied over rolled roofing, and some are applied over foam roof material. Sometimes roof coating contractors use elastomeric coating in conjunction with polymembranes (Tietex) and to cover the entire roof. Each of these substrates age at different levels. Here are a few considerations for each of these substrates.

Roof Paper. Most flat roofs fall into this category. Roof coating materials will usually last 4-6 years (assuming two coats of premium materials) on this substrate. Acrylic coatings applied directly on new roof paper will not last as long because the coating is soaked up by the roof material.

Rolled Roofing. Rolled roofing is its own roof system and is considered a 20-year system. After 20-years the roof material will need to be replaced – unless it has been coated with acrylic roof coating. Coating the roof with cool coating helps protect the bitumen roof materials and helps keep the roof cooler. Coatings can last much longer on these substrates because they can be allowed a longer period before recoating. A good rule of thumb is to coat rolled roofing material with at least one coat every 5-7 years and two coats if it is aging more rapidly.

Foam Roofing Material. Many roofs in the southwest have been coated with an inch or so of foam. Code requires this foam to be coated with acrylic coating within 24 hours after the foam is applied. Unfortunately, these style substrates move more than usual in heat. This causes the roof coating to break down sooner. Also, the foam coatings are not applied uniformly which leaves minor dents that hold water. Water will break the coating down sooner in these areas. It is our opinion that roofs that have been coated with foam should be recoated every 3-4 years with two coats of premium roof coating.

Polymembrane Material. Polymembrane is polyester rolled up like rolled roofing. It is saturated with roof coating or acrylic roof primer and then laid down on the roof. These membrane holds the coating and protects the roofing material underneath. If the membrane was applied with primer and coated with two coats of roof coating the roof may last 5-7 years before needing to be recoated.

There are many reasons that come into play when determining how often you should coat your roof. We have outlined a few of the most common and more prevalent reasons. Every good roof coating contractor should be able to explain the different reasons. If you would like a free inspection Desert Sky Roofing would enjoy checking your roof and help you to determine how long your coating will last or if it needs to be recoated. We have five different programs that will fit any flat roof (click here) and we are sure we have a program to help you. Give us call at 520-444-5218.