Is it possible to get a skylight to fit an irregular space on the roof? I'd like to fit a skylight into the location shown below, but extending all the way down to the bend in the roof. This would basically add a right triangle to the bottom of the rectangle.

If it's possible, would there be any concerns regarding water drainage in an arrangement like this?

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1 Answer 1


You can probably get custom built sky lights made up but I would strongly suggest not doing that. Skylights eventually need replacing as they age due to either clouding up or the seals give out due to thermal expansion/contractions. Finding a replacement for a custom unit can be a big pain.

Standard sky lights are made to fit between standard rafter spacings. The customization that you propose could interfere with how the roof is framed at the valley (which you called a bend).

What I have done in the past to make sky lights appear bigger than they actually are is to make the "tunnel" from the roof down to the interior ceiling have sloped sides down to a bigger opening size in the ceiling. This works especially well if the house is built with rafters that are NOT trusses. The ceiling joist spacing in the area needs to be widened to the desired width but this can be done by someone experienced with framing.

If the roof is made of trusses then the "tunnel" can be tapered in the spaces between the rafters but left with straight down walls parallel to the sides of the roof trusses.

  • 1
    +1 A custom unit with a lower edge in the valley between the roof angles would also be in a heavy flow of draining water, increasing the chance of leaks.
    – bib
    Aug 4, 2014 at 15:17
  • 1
    I totally agree. The best place for skylights is out on normal roof surface away from features like valleys, hips and so forth.
    – Michael Karas
    Aug 4, 2014 at 15:43

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