Dormer or Skylight? What’s the Best Choice for You

The way you choose to light the attic is very important for the aspect and atmosphere of the rooms you have there. Even their shape can be influenced when choosing a certain lighting solution. Here are the advantages and disadvantages of choosing a dormer or skylight, personal taste being of course determinant.

A dormer is a vertical window structure built out of an inclined roof, while a skylight is an inclined window built within the roof.

Dormer or skylight? Advantages and disadvantages of the dormer

  • Dormers reduce the area of inclined walls in the attic and are easy to clean.
  • A dormer provides 30 – 40% less light than a skylight. But its height and way of installment can influence the amount and quality of light it provides.
  • As it’s a whole structure that goes out the roof, building a dormer requires extra roofing material and it’s usually more expensive that installing a regular skylight.

dormer or skylight

To make a dormer as functional as possible, follow these simple rules:

  • Allow for a window surface that’s at least 1/8 of the total room area.
  • The window sill should be placed around 35 inches high above the floor.
  • The window height should be around 50 – 60 inches.

Dormer or skylight? Advantages and disadvantages of skylights

  • A skylight allows 30 – 40% more light in than a dormer, spread more uniformly around the room.
  • Still, these windows get dirty easier and are more difficult to clean. The more inclined they are, the more difficult their maintenance is.
  • During winter they can get covered in snow, which makes lighting and airing the room difficult. In summer, on the other hand, they can cause overheating the room.
  • Skylights are a more comfortable way of having more windows one next to another, which can make a more interesting design.

dormer or skylight

Skylight recommended parameters

Since this window typically lets in more light, it may cover around 1/8 – 1/10 of the room area. If it’s too large, you’ll spend more on heating and cooling the room.

A skylight should be 35 – 43 inches wide and placed 73 – 80 inches above the floor.


Photo credits:,

You may also like...