How To Protect A Residential Flat Roof From Solar Damage

Posted on: 2 June 2021


Residential flat roofs are stylish, versatile, and cost-effective structures. However, one of the major drawbacks of this roof design is its susceptibility to solar damage. Since a flat roof doesn't have a pitch, the entire surface is exposed to the sun during the day. This exposure can lead to premature failure down the road. Therefore, note the following potential forms of sun damage on a flat roof and how to prevent them.

Heat Damage

The sun's heat increases your roof's temperature, which can present problems for the structure. Intense heat causes the protective coatings on your roof to dry and become brittle. Over time, these coatings begin to wear, which speeds up the degradation of roofing materials. During summer, the roof's underside forms condensation due to the temperature differences between the roof's surface and the conditioned indoor spaces. The moisture promotes mold growth and expedites the wear and tear of roofing materials.

You can protect your flat roof from solar heat by using reflective or energy-efficient materials. Materials such as metal reflect solar rays instead of absorbing them, which helps prevent premature aging. Alternatively, choose light colors over dark ones to reduce heat absorption. Also, install quality roof insulation to prevent heat gain during summer.

Ultraviolet (UV) Radiation Damage

UV rays are as damaging as solar heat. When the rays hit your roof, a chemical reaction occurs between them and the roofing products. This reaction accelerates the wear and tear of the materials. UV rays also dry out the oils that promote expansion and contraction. The roofing materials become dry and brittle and more susceptible to damage.

Some flat roof materials hold up better to UV radiation than others. For example, Thermoplastic Polyolefin (TPO) and modified bitumen have excellent UV-resistance properties. TPO has reflective membranes, while modified bitumen comes with reflective granules that reflect solar heat and UV radiation. Flat metal roofs can also be coated with UV-resistant coatings to extend the lifespan of the structure.

Thermal Expansion

High daytime temperatures cause roofing materials to expand. As the sun sets, temperatures drop, and the roof contracts. The continuous expansion and contraction can cause thermal shock. Since materials expand and contract at varying rates, your roof may suffer damage. As a result, you may notice cracks and gaps on joints and connections, which increases the risk of leaks.

Thermal shock occurs if your roof absorbs heat during the day. Therefore, you can prevent it by investing in reflective materials or coatings. A reflective roof reflects solar heat and only expands a little. With minimal heat absorption, the structure becomes less susceptible to excessive thermal expansion.

As you install a flat roof, address the above forms of sun damage that may shorten the structure's lifespan. For more information, reach out to a local roofer.