Roof Damaging Effects of Ultraviolet – Part I

What are the most common roof damaging effects of ultraviolet?

Ultra Violet is a type of radiation, very similar to observable or visible light, but with a wavelength shorter than the color of light of Violet. Ultra Violet light is also on the same spectrum of radiation as x-rays, except ultraviolet light has a radiation wavelength longer than x-rays.   Ultraviolet is present in everyday regular sunlight, but its not visible to the naked eye.    Extended exposure to sunlight is understood to be damaging and harmful to human skin, but it’s particularly the ultraviolet rays in sunlight which caused the majority of the damage. 

Ultraviolet Damage On Building Materials

The same ultraviolet rays also cause significant accelerated deterioration and damage to building materials. Some building materials though are largely resistant to the harmful effects of ultraviolet rays, examples include stone, concrete, and even historic kiln fired clay brick and mortar.   Roofing materials though are generally significantly susceptible to the harmful effects of ultraviolet rays. Some modern materials such as single ply roof membranes like Thermopolyolefin (TPO) membranes do a pretty good job to resist and even reflect a lot of the harmful rays back into the atmosphere.  

In the pictures below, we show examples of ultraviolet damage to roofing materials and other materials that are part of the building assembly. We’ve placed a folded dollar bill to represent the scale because the pictures are taken out of context from other building materials and you can’t get a concept of the size of the cracking and types of deterioration without some sort of scale reference. Since dollar bills are consistently sized, we thought this would be a good standardized reference in lieu of a tape measure.

examples of ultraviolet damage

How Roof Seams Should Be Installed

The next picture below shows the overall expanse of that particular rowhome roof. This particular roof is a hodge podge tapestry of mixed up layers of modified bitumen membrane. At the time that we looked at this roof, we believed that the previous contractor had a very poor understanding of the methods and requirements for installation of roofing because they ran the seams in the wrong direction. Seams of a roof should overlap in concentric order so that you begin with the lower part of the roof and run the seams perpendicular to the flow of water then the successive layers of membrane will be installed on top of that next layer so that there is a lap covering the upper edge of the lower layer.

roof damaging effects of ultraviolet

After the initial installation, since the roof was never coated with a high or moderate reflectivity protective application, The roof has deteriorated quickly, in just a few years it has started to resemble the contour and texture of the skin of an alligator.

how ultraviolet roof damage looks like

Ultraviolet Rays Damage Examples

It’s not just roofing materials which are damaged by exposure to ultraviolet rays, other materials are also damaged and experienced rapid deterioration from exposure to direct sunlight and the harmful effects of ultraviolet rays. In the picture below you can see a rope that has been left on the roof for a few years and after just a short period of time that rope has deteriorated into scraps and tatters.

ultraviolet rays damage on things

ultraviolet damage on materials

How To Maintain Your Roof

Smart proactive replacement, construction, upkeep and maintenance of low slope roof systems requires an enthusiastic interest and understanding of waterproofing principles and building science.   Here in Washington DC, historic and modern residential and commercial buildings are extremely expensive and the roof and related systems provide the shield that preserves the building. 

We encourage all of our clients, and all readers of this article and to our blog in general, to prioritize the value of quality construction and building maintenance, and develop a relationship with our company.  You can learn a lot more on our blog.  Feel free to check it out.  If you have questions about the roof and related systems of your building in Washington DC, contact us or fill out the webform below and drop us a line.  We will be in touch if we can help.

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