The Simplicity of a “Curb Mounted” Skylight

At Skylights for Less, we like to differentiate our skylights based on the type of installation or application that they would be used on. Because of this, the most frequent question we receive is regarding the difference between VELUX Curb Mounted Skylights and VELUX Deck Mounted Skylights. We thought we’d take this week to focus on the benefits and installation of the Curb Mounted Skylight in hope that we can answer some questions you may already have about them.

When you think of a curb, you probably think of the raised side of the road which is designed to prevent cars from driving on the sidewalk and lawns. A VELUX Skylight’s curb was designed with the same idea – to keep unwanted things like moisture out. The Curb is defined as a box, which is attached to the opening in the roof. The inside of the curb’s “box” should line up with the roof’s opening. This dimension is referred to as the “Inside Curb Dimension” or “daylight opening”. The outside of the box is referred to as the “Outside Curb Dimension”, which is how we determine the correct size of Curb Mounted Skylights. Important to remember, the outside of the box will need to be protected. Flashing pieces, roofing material, or some type of shielding material needs to be attached and layered around all sides of the curb.

VELUX Curb Mounted Skylights Installation Steps

  1. Determine the opening in the roof. If using standard sizes, 2 x 4 or 2 x 6 wooden planks to make the Curb or Box to fit the opening in the roof, the inside curb dimension and outside curb dimension should have a 3” difference in size.
  2. Make sure the Curb is securely attached to the roof. This is where an installer or handyman is needed to determine the best method to keep it secure in all types of weather and determine the best way to “flash” or “seal” the curb.
  3. Once the curb is ready, the Curb Mounted Skylight will lay nicely over the curb and be nailed and sealed securely. A secure Skylight is one that is not too tightly fitted or too loosely fitted. Curb Mounted Skylights are manufactured to a “Make Size”. This make size is One Inch larger than the outside curb dimension. This allows for extra material to be added to the curb. If you are replacing a Skylight and the curb may not be in perfect condition or new flashing or roofing material is necessary, extra material can be safely added and allows room for adjusting the curb.

Curb Mounted Skylights can be purchased with Glass or as Double Domed Skylights. Many sizes and options are available and best of all, the curb mounted skylight offers an inexpensive way to replace an older skylight. If the old curb is still in good shape (is not worn down by weather and moisture, and is still structurally sound), you’ll likely be able to reuse it for the replacement skylight. That’s right – as long as you’re using a VELUX Curb Mounted Skylight of the same type and size, you won’t have to cut any new openings in your ceiling.

A Curb Mounted VELUX Skylight installed correctly is proven to last the test of time. VELUX is so confident in them that they’ve added a No Leak Guarantee. Read all about it here!