White flat roofs show more dirt than dark-colored flat roofs. Dirt, grime, pollen, bird droppings, and more should not affect the waterproofing properties of your flat roof system, but a dirty roof can be a real eyesore.
Dark flat roofs like black EPDM (ethylene propylene diene monomer) hardly show any dirt at all, even when the roof surface is littered with dirt and grime. So why do building owners opt for white flat roofs in the first place?
A clean, light-colored rooftop is more aesthetically pleasing. It can also reduce your air conditioning and energy needs. In fact, the US Department of Energy says 60 to 90% of the sun’s rays are reflected by a white flat roof. Cleaning your flat rooftop helps to keep the membrane looking attractive, free of debris, and functioning at its best.
So then the question becomes, how do you keep a white flat rooftop clean?
A More Permanent Solution
Washing, although important to do, will only clean the roof. It won’t keep the dirt at bay. So, we’re often asked if there is a more permanent solution.
If your white flat roof is an eyesore because of dirt, a permanent solution is to apply a colored roof coating. Gray is a good color because it will still reflect the sun and the dirt doesn’t show very well. Another good choice is a tan color as it looks more natural and less industrial.
Whether your roof is white or dark, there is a wide range of color choices for commercial and industrial flat roof coatings. Dark colors work well if your goal is to hide the dirt but, as said earlier, it comes at the expense of energy efficiency.
Customers who opt for a darker roof color usually have a good reason. Resorts and hotels, for example, sometimes choose a color they think will appeal to guests who look at the roof area in question. Office building owners sometimes do the same thing, considering they will have workers who can view the rooftop from indoors.
If you decide to go this route, then you need to consider your roof coating options.
Roof Coating Options
There are two levels of roof coatings. If you just want a color change and do not need or want a manufacturer’s roof warranty, the roof can be power washed and a new coating roll applied. If you want a full roof system warranty, it’s best to power wash and reinforce all the seams and penetrations with fibered coating before applying the top coat. The top coat should also be thicker than 24 mils wet to qualify for a roof warranty.
Doing a full roof coating costs more, but it will last longer and be more durable because the seams have been reinforced and you have added extra coating.
If you are concerned about the color of your flat roof or the amount of dirt that is accumulating on top of it, you always have the option to enlist the help of a flat roof professional. Many flat roof experts are happy to provide a free evaluation and estimate.
Jared Van Vranken is Vice President and lead estimator at Flat Roof Solutions in Malvern, PA. Jared has directed the installation, repair, recovery, and replacement of commercial flat roofs for more than a decade at Flat Roof Solutions. He guides clients in selecting the best roofing material for their needs and budget.