News in Skylights: Let the Sun & Passive Solar Heat In

By John Voket


In our previous two segments covering skylights, I have learned that a skylight installation project is not for casual DIY-ers. In this final report, we'll cover the few remaining issues to consider if you plan on letting the sunshine and its passive solar energy shine in this winter.

Our sources at the US Dept. of Energy say that in addition to following the manufacturer's guidelines, it's also important to consider slope and moisture control during installation.

The slope or tilt of the skylight affects solar heat gain. A low slope will admit relatively more solar heat in the summer and less in the winter, exactly the opposite of what is desirable.

As a general rule of thumb, you want to achieve a slope equal to your geographical latitude plus 5 to 15 degrees. At least one skylight manufacturer makes a prefabricated, tilted base that increases the angle of a skylight above the roof.

Water leaks are a common problem with improperly installed skylights. Avoid water leaks by:

  • Mounting the skylight above the roof surface
  • Installing a curb (a raised, watertight lip that helps to deflect water away from the skylight) and flashing
  • Thoroughly sealing joints
  • Following the manufacturer's guidelines.

It is also prudent to apply a layer of sheet waterproofing over the flanges/flashing of the skylight. This is generally installed under the finish roofing material as an aid in protecting against ice dams. Avoid water diversion devices such as roof crickets or diverter strips, as they often create more problems than they solve.

Again, the DOE experts say. Even the most energy-efficient skylight must be properly installed to ensure that it achieve its energy performance, so they say it's best to have a professional install your skylight.



Reprinted with permission from RISMedia. ©2013. All rights reserved.