A skylight replacement doesn’t need to be complicated, but there are certainly things you need to consider before replacing your skylight.

Skylights, like all components of our home will require replacement at the end of their usable life.  The difficulty of skylight replacement depends on a multitude of factors including Type of skylight being replaced, application of skylight being replaced, size of skylight being replaced, and availability of direct size replacement.  While for most homeowners and even most contractors these factors can seem overwhelming, and possibly even not worth the trouble of navigating,  this blog will aim to break the process down step by step to make it more manageable.

What type of skylight do I have?

The first factor to consider when beginning the process of replacing your skylight is to determine what type of skylight you have.  There are several types of skylights you could have on your home.  The three main types of skylights you would be most likely to run into on the average home would be a deck mounted skylight, a curb mounted skylight, or roof window. 

Deck mounted Skylight

A deck mounted skylight is a skylight that mounts directly to the roof deck, via a nailing flange like one you would find on a new construction window.  Deck mounted skylights are typically lower profile, and more energy efficient than some of their counterparts.  Deck mounted skylights can only be installed above 14 degrees, which makes it a poor choice for flat and lower pitch roofs.

Flashing a curb in preparation for skylight

The second type of skylight you’re likely to find on a residential roof would be a curb mounted skylight.  A curb mounted skylight is skylight which sits on top of a curb, like a shoebox lid.  The curb mounted skylight can be installed on just about any application from a flat roof, all the way up to an 85 degree roof. The curb is flashed into the roof deck, and the majority of the waterproofing takes place at this point. The advantages to a curb mounted skylight, they are very easy to service and replace as the whole skylight can be removed from the roof in a matter of minutes.  The disadvantages to a curb mounted skylight are they are typically more bulky than their deck mounted counterparts, and tend to stick up higher off of the roof deck as well.

Top-Hinged Roof Window

The third skylight type your likely to run into in a residential setting is commonly known as a roof window.  A roof window is a European product that was designed for in reach applications in which you can physically grab the skylight to open it.  These windows are widespread especially in the northeast and have a tendency to be installed in areas where they are unusable due to high ceiling height.  In most cases if you have a roof window, there will be a direct skylight replacement size, however there are a few situations in which this is not the case.  Roof windows have many advantages when they are installed in the right application, including energy efficiency, and an aesthetically pleasing interior and exterior design. The main drawback to a roof window is they do not come with an insect screen, and although there Is an option for adding one, the screen is bulky and complicated to install and use.

What application is my skylight on?

There are several applications in which you could find a skylight on your home.  The main and most common applications you are likely to find in a residential home would be a pitched roof, with asphalt shingles, a pitched roof with standing seam metal panels, or a flat roof with a membrane such as EPDM. Replacing a skylight on each of these applications is vastly different, and each need different considerations taken into account.

Skylights installed on asphalt shingles

Replacing a skylight on a pitched shingle roof, is by far the most common application we find during skylight replacement.  Whether the new skylight is deck mounted or curb mounted, if it is a standard size, it will have an engineered flashing kit available that can be interwoven into the new shingles. One of the considerations when replacing a skylight on a shingled roof is getting the new shingles to match the old shingles.  Although this may seem like an easy task, it isn’t.  Unless the roof is brand new within the past year or two, even an exact brand and color match will likely look different.  In these scenarios if a perfect match is mandatory, we recommend replacing the whole roof section that the skylight sits on. Another consideration when replacing a skylight on a shingled roof is the age of the roof.  If a roof is not in serviceable condition, it is not recommended to replace the skylight without replacing the roof.

Skylight install on metal roof

Replacing a skylight on a pitched metal roof is one of the more complicated skylight replacement applications one can run into.  Standing seam metal roofs are difficult to disassemble, and often times the panels around the skylight were bent specifically for the existing skylight and may or may not be able to be re used for the new skylight.  If you have a curb mounted skylight that is already flashed into your metal roof, replacement is easy, in that you simply need to order the correct size curb mounted skylight.  However, if you have a deck mounted skylight that is flashed into your metal roof, your best option for replacement is to go back with a curb mounted skylight.  The most difficult part to the replacement will be to modify the panels in a way that will make the curb watertight, but it will allow for an easy future replacement.

How to replace a skylight on a flat roof. Replacing a skylight on a flat roof, as with most skylight replacement applications, has its own nuances to consider.  The first consideration is what type of skylight is on the flat roof, most likely it is a curb mounted skylight because those are allowed to be installed with little to no pitch.  Sometimes however you might find a deck mounted skylight built up on a large, pitched curb which allows it to meet its minimum pitch requirements.  In Either case it I best to go back with a curb mounted skylight.  The best practice is to remove the existing skylight and curb down to the roof deck and install a new curb, and new flashing and roofing. One consideration on a flat roof skylight replacement, is adding a small amount of pitch to your curb.  When a curb is built with no pitch and is installed on a roof with no pitch, water will tends to collect in the center of the glass and over time will leave an unsightly stain on the glass that is hard to remove.

What size is my skylight? Is there a direct replacement for my skylight size?

The single factor that will have the most impact on how easy or how difficult your skylight replacement will be is the size of your skylight.  If the existing skylight opening you have now coincides with a standard size skylight that is currently available today, then the replacement will be pretty straight forward.  In these cases, you will likely only need a bead of caulking or perhaps some trim in order to make the installation look complete on the inside.  If the existing opening you have does not correspond with a standard skylight size that I available today, the installation becomes more complicated.  Your first option is to make the existing opening you have now smaller, to correspond with the closest standard sized skylight rough opening available.  This option is good if your looking for options in your new skylight such as venting or shades.  Another option available to you if your existing rough opening doesn’t coincide with a standard size skylight is to replace it with a customer FCM (fixed curb mounted) skylight.  These skylights can be made to your specific dimensions, however they do not have flashing kits available, and therefor a custom flashing kit will need to be fabricated on site.

As you can see there are many factors to consider when deciding to replace your skylight.  Due to this, it makes sense to hire a skylight professional to guide you through the process.  At synergy skylights, we walk you through the entire process, laying out all of the available options and prices, and helping you choose the replacement option that suits your needs and your budget. 

Have questions? Contact our skylight experts today.

If you have questions about your skylight replacement or are considering replacing you skylights, call Synergy Skylights at 978-233-1622.


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