How sunlight degrades exterior paint.

Key takeaways from this article:

• Sunlight is the primary reason your exterior paint and stain degrade and leave your home exposed to the elements.
• Degradation of paint can be seen as fading, chalking, and cracking.
• Deck stain breaks down on deck tops because the sun beats down on such a large surface area and water (rain, snow, ice) puddles.
• Light exterior paint colors appear to degrade slower than dark ones (which absorb heat and UV rays).

Many homeowners assume that wear and tear on painted surfaces comes primarily from physical contact, like foot traffic on decks or hands touching walls. However, one of the most significant and overlooked factors affecting paint durability is sunlight exposure.

How Sunlight Affects Exterior Paint:

Sunlight (ultraviolet (UV) radiation) is a major culprit in breaking down paint and causing fading, chalking, and peeling. UV rays degrade the chemical bonds in paint, which leads to:

• Color Fading:  Darker colors, reds, and blues are particularly vulnerable to fading under prolonged sun exposure because they absorb more of the UV rays (like black leather seats in a car on a hot day).
• Chalking:  Chalking occurs when the paint’s binder breaks down due to prolonged exposure to sunlight and weather conditions, leaving a powdery residue on the surface. You can check for chalking by running your hand along the siding. Iif a chalky residue appears, the topcoat has deteriorated, exposing the underlying pigment (this is the chalk on your hand). This indicates that the protective barrier is gone, and your home is vulnerable to further damage. When chalking is evident, it’s time to repaint to restore both protection and appearance.
  

  Take our 20-second quiz to find out if your exterior needs repainting.

• Cracking and Peeling:  We’ve all seen this on homes that haven’t been painted in a while. As UV exposure weakens the paint, it becomes brittle and loses adhesion.  This causes the paint to dry out and crack.

Sunlight degrades your deck stain:

Most people believe that deck stains wear down due to heavy foot traffic. While foot traffic plays a role, the real culprits are constant sun exposure and water puddling.

• Beating Sun:  Horizontal surfaces like decks take direct exposure to sunlight all day, which accelerates UV damage and dries out wood, leading to cracks and splintering.  You’ll notice that areas of your deck remain pristine when they are covered by items such as grills and tables.
• Puddles and Water Damage:  Unlike vertical surfaces like the deck railings, horizontal surfaces do not dry as quickly.  This means that water puddles sit longer. This prolonged moisture exposure causes wood rot, mildew growth, and stain breakdown.

  You’ll also notice that your deck railings require staining far less often than the deck surface. This is because their vertical position allows gravity to shed water more quickly than the horizontal boards of the deck top, which retain moisture longer and wear down faster.

How to Protect Your Paint and Stains from Light Damage

While light exposure is inevitable, there are steps you can take to prolong the life of your paint and stain:

1. Choose High-Quality UV-resistant paints and stains – Many exterior paints and deck stains now contain UV blockers that help slow down fading and degradation.  Try Sherwin Williams Rain Refresh exterior paint for not only UV protection but also to remove the dirt and debris from your home each time it rains (bonus!)
2. Use Lighter Exterior Paint Colors:  Dark colors absorb more heat and fade faster. Lighter shades reflect more sunlight and last longer.  Think of how much hotter a black car is than a white car on a hot summer day.
3. Apply a Protective Topcoat:  For high-exposure areas, a clear UV-resistant sealant can provide an additional layer of defense.
4. Properly Maintain Your Deck and Siding:  Regularly clean, re-stain, and seal your deck to prevent moisture buildup and prolong the life of the stain.  Unfortunately, this means that you’ll need to stain wood decks every 1-2 years.  If you have the choice of wood vs. composite decking like Trex, the composite decking material will save you gobs of money in the long run, even though it is more expensive to install upfront.
5. Strategic Shading:  If possible, use awnings, pergolas, or trees to provide shade and reduce direct sun exposure on painted surfaces.

Want expert advice on choosing the right UV-resistant paints and stains? Contact us today for a consultation!