The Effects of UV Light on Various Types of Hardwood Floors

August 27, 2009 | by Ethan (email) |

Carpet on hardwood floorIf you’ve just finished installing hardwood floors, or are in the market, you should know that hardwood floor may change color. Sunlight affects each wood species differently, but most will darken over time until it’s fully seasoned. This post will focus on how sunlight will affect your floor so you can make in informed choice.

Discoloration Caused by Sun Light

Sunlight contains Ultraviolet type A and type B rays (UVA & UVB). These rays can bounce off water, sand, and even penetrate glass. Many people know that UV light can cause skin cancer, but it can also change the color of furniture, carpets, hardwood flooring and artwork. In short, UV light can cause your furnishings to take on a prematurely aged look.

UV Effects on Hardwood Flooring

UV light causes wood to change color, especially exotic species. Depending on your type of wood, UV exposure may lighten or darken your flooring, but most tend to darken. The effects are very evident where area rugs or furniture cause an uneven change in color. Typically, color changes occur more rapidly at first and are indistinguishable after 3 – 6 months (depends somewhat on exposure).

It’s tough to find the effects of UV light on specific wood species. I’d encourage readers to comment with their own experience.

  • Cedar – sunlight bleaches out unfinished cedar floors and causes them to darken after a finish is applied.
  • Brazilian Cherry – darken relatively quickly.
  • American Cherry – darkens to a deep red.
  • Teak – turns darker brown.
  • Yellow / Red Oak – slightly lighter over time.
  • Maple – lighten over time.
  • Brazilian Walnut – darkens causing a more uniform look.
  • American Walnut – lightens over time (nathalie comment).
  • Brazilian Ash – little change over time.
  • Purpleheart – turns more of a brown.
  • Tigerwood – darkens quickly! (nathalie comment)

UV Window Films Protect Hardwood Flooring

One way to counteract UV rays is to block them. If you prevent them from entering your home, they can’t damage your hardwood floors. New windows have lots of innovative features like double and triple pane glass, inert gas insulation, and non-conductive window frames. UV blocking films are an important feature you should consider when replacing your windows.

These films can also be installed on pre-existing windows. You can opt to have a professional install them, or tackle the project yourself. Either way, UV films not only protect you and your family, but they also protect your home and furnishings by blocking up to 99% of these rays.

What do you think? Has your floor changed color? Do you have a UV coating on your windows?
Image courtesy of back_garage

12 Responses
  1. Very informative thank you. Many people are unaware of this. Also here are some other species and how they react:
    American Walnut – one of the few that actually lighten over time
    Tigerwood – THE fastest changing most UV sensitive of species… try a fun experiment place asticky note on a board.. put it in direct sunlight for a few hours and you will be amazed! darkens up a lot!

  2. Ethan says:

    @Nathalie, thanks for the comment. I’ve updated the post

  3. Evelyn Garcia says:

    I put hard wood floors on the family room three weeks ago. Now I did the kitchen. The hardwood floor in the kitchen is ligther than the wood floor in the family room. We use the same producto for both floors. The contracto told me that the wood floor in the kitche will dark in three weeks. This is true? When the family room floor was done it was on one color and did not change.

  4. Ethan says:

    @Evelyn, What species of wood did you put down? When installing hardwoods you’ll get some differences even between boxes. That’s why it’s important to open several boxes rather than working through one at a time.

  5. Sandy says:

    We have brazilian cherry floors and used area rugs because of our dog. Now we have lighter areas where the rugs are. What can we do to even out the color? If we remove the rugs, how long will it take for the color to darken since it’s October now and there isn’t as much light? We don’t want to go to the expense of refinishing the floors.

    Thanks for any suggestions.

  6. JustME says:

    I’ve heard of cherry changing colors, but didn’t realize oak would. So far we’ve not noticed any changes in the eight years since our floors were laid.

  7. chuck blood says:

    Are the UV rays harmful during the winter months?

  8. Jeff says:

    Can you use special lights to even the color after a rug is removed?


  9. Ed Eaglehouse says:

    What wavelengths of UV light? There are several classifications: UVA is 320-400mm, UVB is 290-320mm, and UVC is 10-290mm. The shorter wavelengths have higher energy and the cause more damage to organic tissue. I’ve tried UVA, what is called “black light”, to darken wood and it does basically nothing. UVB causes sunburns. UVC damages DNA and is used for disinfecting. Can anybody report the effects of either UVB or UVC?

  10. rick says:

    I installed 6×6 squares of parquet oak (species not known) many years ago. Two aluminum rods on the back side held each 7 strip square together.

    Since I didn’t want the ‘normal’ L-R/U-D interleaved parquet pattern, I broke some squares into groups of 4 and 3 strips, then interleaved them with the ‘normal’ squares, forming a unique pattern.

    Spouse put a large area rug over most – but not all – of that wood flooring. When she removed the rug for cleaning, the portion that remained exposed all these years had darkened beautifully, while the segments under the rug was lighter.

    I thought that the rug had absorbed the oak’s darkening oils but reading several search engine entries tells me that leaving the formerly covered flooring exposed will cause it to darken to match those that were uncovered, over time. What say you?

    • rick says:

      This is a followup to my above post.

      After leaving my wife’s rug off of the flooring since the above post, and exposing the previously covered flooring to southern sunlight (through full height door glass x3), the remaining flooring has not noticeably darkened.
      This leads me to believe that the darkening effect is caused by the wood’s oils ‘percolating’ to the flooring’s surface, more so than the sun’s UV rays as stated elsewhere in this web site.

      I wi;; continue to leave the previously covered wood exposed and report back here again in a future ‘reply’ comment.

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