Green Renovation: Adding Skylights, Part 3

Jim Mallery

Part 3 of a six-part series, Green Renovation: Adding Skylights

Adding Skylights, Part 2

The first two articles of this series looked at basic considerations of adding skylights to your old house including basic structural requirements, energy efficiency, types of skylights and costs. The next articles will explore the actual steps of installation.

Skylight Placement: Overcoming Obstructions

Inspect the proposed skylight location for electrical wiring, duct work or venting.

It isn't that hard to relocate wiring in the attic, but you might be able to avoid it by moving the light to another rafter bay or up or down a foot.

If you move the wiring yourself instead of hiring an electrician, remember these basics:

  • First, flick off your circuit breaker before beginning work!
  • If you are splicing wires to get extra length to move them, you have to use junction boxes to protect the splices. The junction box has to be visible above the attic insulation.
  • Make sure you are using the correct-sized wire. A 20-amp circuit (the breaker will tell you the amperage) requires a 12-gauge wire. A 15-amp circuit can use 14-gauge.

Unless you have a very spacious attic, you probably want to cut the ceiling hole before you frame the well. That way, you can work on the framing by standing on a ladder and working through the hole rather than scrunched over in the attic.

Planning Skylight Placement Before You Cut

Once you have decided the location for the skylight, push the insulation aside and pop nails through the ceiling at the four corners of the cutout. Then go to the room below and look at the nails, visualizing the opening to make sure you have it esthetically located. You might even outline the rectangle with twine to better visualize the hole-to-be. It's a lot easier to visualize the cutout while standing in the room below than while doubled over in a dusty attic.

There is no rule on the shape of the ceiling opening for the skylight. You can drop the shaft down at 90 degrees from the roof, or you can flair the opening to allow more light to enter. Most people would flair the opening.

Tips on Making the Cut

When you are satisfied with the placement, you can cut the ceiling drywall.

  • Saw. The narrow blade of a drywall saw makes it difficult to cut a straight line. Once you have started the cut by punching through the drywall with the pointed drywall saw, switch over to a standard carpenter's hand saw; it is faster and will cut a straighter line.
  • Dust Catcher. A helper holding a 5-gallon bucket under the saw will stop an enormous part of the dust problem. Vacuuming the edges of the cut drywall will also pick up most of the dust that otherwise would pollute the house.
  • Debris. A helper can also catch the cut out drywall to keep it from crashing to the floor. Be sure you are both wearing appropriate respiratory protection.

With your ceiling hole cut, you are ready to frame the well of the skylight. In Part 4, we'll explain framing and get you up on the roof to let in the light.

Adding Skylights, Part 4

About the Author

Jim Mallery, a semi-retired journalist and onetime registered contractor, has extensive experience remodeling, repairing, and rebuilding homes.

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