The Simplicity of a “Curb Mounted” Skylight

Curb Mount Skylight Guide: Benefits & Details

Curb mount skylights are a convenient, stylish, and popular method of bringing natural light into a home or office. They can be installed in new construction or added as an aftermarket upgrade to an existing building. Curb mount skylights come in a variety of shapes and sizes, and are made from a variety of materials, including acrylic, polycarbonate, and metal.

For a while, curb mounting was the main method of installing a skylight. With the advent of sun tunnels or tubular skylights and other methods, curb mounting is not as common as it once was – but its undeniable benefits remain.

Perhaps the strongest appeal for those who purchase curb-mounted skylights is the simplicity of changing an old skylight for a new one. Since the curbing remains intact, all you need to do is swap out the skylight itself. This is a much simpler process than, for example, disrupting an entire roof section to install a new skylight.

This article will explore the benefits of curb mount skylights in detail and offer advice on what to look for when shopping for one. We’ll also clarify how curb mount skylights differ from deck-mounted ones. Let's dive in!

What is Meant by a Curb Mounted Skylight?

Put simply, a curb mounted skylight is one that is installed on the roof near, or flush with, the edge of the roof. The skylight itself sits on an outside curb or frame that is mounted to the roof; this frame can be made from a variety of materials, including metal, plastic, or wood.

Curb mounted roof windows come in two main varieties: venting or fixed curb mount skylights.

Fixed skylights do not open and are generally used to provide light and ventilation in smaller spaces such as bathrooms or closets. Venting skylights, as the name suggests, have a built-in vent that allows them to be opened for ventilation. This type is generally used in larger spaces such as kitchens and family rooms.

curb mount skylight

Velux Curb Mounted Skylight Benefits

In 1940s Denmark, the Velux Curb Mounted Skylight was born as a no leak, efficient way to bring natural light into basements. Years later, Velux skylights have only grown in popularity for both residential and commercial properties, along with other brands like Fakro. The curb mount skylight offers a number of benefits that are worth exploring:

  • They're easy to install - Curb mounted skylights typically require less installation time than other types of skylights. This is because they're mounted directly to the roof, rather than requiring a frame to be built around them.
  • They're leak-proof - Curb mounted skylights are typically made with a watertight seal that prevents leaks and keeps moisture out. Unlike skylights that are installed in the middle of a roof, curb mounted skylights don't have as many opportunities for water to seep in.
  • They're easy to clean - Because curb mounted skylights are typically smaller than other types, they're also much easier to clean, which is especially helpful if your skylight is in a hard-to-reach spot.
  • They allow for natural ventilation - Venting curb mounted skylights provide fresh air and sky views, and they help to reduce moisture and heat buildup in a room. The airflow makes them an ideal choice for spaces like kitchens and family rooms where natural ventilation is important.

This type of installation also allows for a more open view from below, as there is no need to cut into the roofing material as there would be with a traditional skylight installation. The curb mount skylight has become increasingly popular in recent years as homeowners look for ways to add natural light and improve the overall aesthetics of their homes without breaking the bank.

One of the most important considerations when installing a skylight is the type of flashing and shield material you use. This will protect your home from water damage and ensure that your skylight lasts for years to come.

There are a few different types of flashing available, but the most common is sheet metal flashing. It's important to use a high-quality flashing material that is corrosion resistant, as it will be exposed to the elements.

Shield materials come in a variety of options, but the most common is tempered glass. This type of insulated glass is strong and shatterproof; its special glazing makes it a good option for areas that are susceptible to wind and debris.

Curb Mounted vs Deck Mounted Skylights

There is often confusion around the different types of skylight installation, and as such, it can be confusing to know which type of curb mounted skylight is best for your needs. Let's take a look at the key differences between curb and deck mounted skylights.


As mentioned, curb mounts are installed on or near the edge of the roof, while deck mounts are installed in the middle of the roof. The reason for this is that the curb mount is designed to work with the slope of the roof, while the fixed deck mount is installed into the roof deck.


Curb mounted skylights are typically smaller than deck mounted skylights, as they don't need to span the entire width of a roof. This makes them a good option for smaller spaces like bathrooms and closets.


Curb mount skylights are unique in that they sit on a literal 'curb' of sorts that is mounted to the roof. Deck mount skylights, on the other hand, require a frame to be built around them, which can add time and expense to the installation process.


Many people prefer deck mounted skylights for their aesthetics, as they tend to sit more level with the flat roof and allow for more unobstructed views. Curb mounted skylights, on the other hand, have a high profile frame that sits a few inches higher off of the roof and can be more visible from below.

Energy Efficiency

Curb mounted lights are typically less insulated, which can lead to heat loss in colder climates – but both curb and deck mount skylights are going to be far more efficient than electric lighting!

Now that you know the key differences between curb and deck mounted skylights, you can better decide which type is right for your home. Curb mounted skylights are a great option for smaller spaces or homes in warmer climates, while deck mounted skylights are ideal for larger areas and colder climates.

No matter what your needs, a curb mounted or deck mounted skylight is a great way to bring natural light into your home!

Which is better: curb mount or deck mount skylight?

When looking for a skylight to install, it can be difficult to choose between a curb mount and deck mount skylight. Both have their own benefits and drawbacks, so it ultimately comes down to what will work best for your specific needs.

Curb mount skylights are typically best for smaller spaces or homes in warmer climates, as they are less insulated and can lead to heat loss in colder climates.

Deck mount skylights, on the other hand, are ideal for larger areas and colder climates. They are more insulated than curb mount skylights and tend to be more aesthetically pleasing.

The most important thing is to choose a skylight that will work best for your specific needs and home. You can seek advice from a skylight specialist to help you make the best decision for your home.

curb mount skylight

Curb Mount Skylight Installation

Because it can cost hundreds or even thousands of dollars to get a skylight installed, you may decide to do it yourself. This means you need to know exactly how to install a skylight for the best outcome. Even if you hire someone else to do it, it's useful to know what's involved.

The tools required include:

  • A hammer
  • Phillips head screwdriver
  • Drill
  • Tape measure
  • Flat pry-bar
  • Box cutter
  • Level
  • Square
  • Saw
  • Shingles
  • Felt paper/underlayment
  • Staple gun, nails, and wood

You can watch the video below for instructions directly from the Velux site, and we'll also run through the steps here.

Determining the Size

First of all, you need to determine the size of skylight you'll be installing. This can be done by measuring the length and width of the opening where the skylight will go.

To calculate the rough opening, you'll need to take the outside curb dimension and subtract the thickness of the roofing materials (usually around ⅜"). For example, if the outside curb dimension is 36", and the roofing material is ⅜", then the rough opening would be 35.62". Use this method to find both the width and length of the opening.

For best lighting, Velux recommends to use a skylight that makes up at least ten percent of your floor area. At this stage, you also need to choose the right flashing kit – and Velux recommends the following:

  • Velux ECL flashing for a roof with a 10 to 60-degree angle
  • Velux ECW flashing for a tile or shingle roof with a 15 to 60-degree angle
  • For a flat roof, flashing is typically provided by the installer

It's always best to consult a professional to ensure you're picking the right flashing kit.

Placing the Curb on the Roof

It's time to place the curb on the roof. This will be the foundation for your skylight. The curb needs to be level, so use a level to check before you drill any holes.

After pulling away the shingles on the roof, use chalk to mark out the precise dimensions you've calculated. This will give you lines to cut along to create your opening. Make sure you install supports in the ceiling structure.

If you're installing a Velux skylight, there are pre-drilled holes in the curb which correspond with those on the skylight. If you're using a different brand, make sure to measure and drill the holes accurately.

The curb can be secured in place with nails or screws, depending on what type of roofing material you have. For asphalt shingles, use roofing nails; for slate, use roofing screws.

To prevent leakage, the curb will then need to be wrapped with underlayment. This can be done with felt paper or a self-adhesive membrane.

Securing the Skylight on the Curb

Now it's time to secure the skylight on the curb. Make sure to measure and drill the holes accurately. The skylight should be secured with screws or bolts, making sure that the sealant is applied around the perimeter of the flashing kit.

How High Should A Curb Be For A Skylight?

The height of the curb is typically determined by the pitch of the roof. The steeper the roof, the higher the curb needs to be. For a roof with a pitch of 5 degrees or less, a curb height of 3" is recommended. For a roof with a pitch greater than 5 degrees, a curb height of 6" is recommended.

There are many additional steps that can be found in the Velux video embedded above, so ensure that you watch it and consult a professional if you're not confident in doing the installation yourself. Professionals are equipped with the tools and knowledge to do a good job, and it's always best to err on the side of caution.

Now that you know how to install a curb mount skylight, you can enjoy all of the benefits that come with them!