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WHAT IS THE
RIGHT SIZE?

It comes down to personal taste and what is architecturally practical.

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THE RIGHT SIZE FOR A ROOM

Many customers ask us, what size of skylight do I need based on the size of the room? Ultimately it is a decision specific to the project and should be considered with your architect or contractor. Here are some general guidelines.
  • It is recommended that a skylight be 5% of the floor area for rooms with numerous windows.
  • For those with few windows consider up to 15% of the floor space.
  • Also, consider the room’s exposure. You may require less skylights with a southern exposure versus northern.
  • If the room is an odd configuration, it may be more efficient to install two well placed smaller skylights instead of one larger unit.

Comparison Size Diagram

NOTE: Diagrams are for visualization purposes only.
Percentages are guidelines, always best to consult an architect.

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SKYLIGHTS DELIVER MORE LIGHT THAN WALL MOUNTED WINDOWS

When choosing the size of your skylight it is important to remember that a skylight provides almost twice the natural light of a wall mounted window.

Skylights angle toward the sky, and are typically not obscured by shrubs, bushes, and trees.

Large trees will have an impact on the amount of natural light.

THE RIGHT SIZE FOR YOUR ROOF TRUSSES

Ideally choose skylight sizes that match your existing roof truss configuration.
24” Centre Trusses
24 Inch Centre Trusses

If one truss is cut on a roof built on 24” centres, then the new opening has an inside rough opening of 46.5”.

  • Skylight sizes are based on roof truss spacing. The majority of homes have trusses installed on 24” centres.
  • The inside rough opening of a skylight to fit between your trusses, and not require removing a part of the truss, would be 22.5”.
  • You then must decide on the length of your skylight.
16” Centre Trusses
16 Inch Centre Trusses

If one truss is cut on a roof with 16” centres, then the new opening has an inside rough opening of 30.5”; or 46.5” if two trusses are cut.

  • Many older homes are built with trusses on 16” centres and the inside rough opening for a skylight to fit in this situation is 14.5”.
  • As above, you can choose from a number of standard lengths. Other leading skylight companies have a very limited selection of sizes for this truss spacing.
  • Columbia offers, as standard lengths; 14.5”, 22.5”, 30.5”, 46.5”, and 70.5” as well as any custom size you may require.
  • As per the Residential Products section, and different model type, glass skylights are available from an inside rough opening of 14.5” x 14.5” to 46.5” x 70.5”, or 2.75 sq. ft. to 24 sq. ft.
  • Any larger unit skylight must be acrylic dome or pyramid. Acrylic skylights are available from an inside rough opening of 14.5” x 14.5” to 94.5” x 94.5”, or 2.75 sq. ft. to 69.5 sq. ft.
STANDARD COLUMBIA SIZES
CUSTOM COLUMBIA SIZES