How To Replace A Skylight On A Flat Roof 

Posted on March 27, 2024

Estimated Reading Time : 4 Min.

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How To Replace A Skylight On A Flat Roof 

Skylights, once just an accessory, are now becoming a necessity for roofs. If you’re a homeowner with a flat roof, you will eventually need to replace your skylight due to damage or wear and tear. But you may be wondering, how would I do this? 

While there are many articles on how to replace skylights on a pitched roof, you might not find as much information when it comes to flat roofs. 

So if you are also looking to replace your skylight, we are here to help. Today we will tackle the burning question: how to replace a skylight on a flat roof. 

What Type Of Skylight Is Best For Flat Roofs? 

When you decide to install a new skylight, you have two main options: curb-mounted vs. deck-mounted skylight. Though both are viable options on a pitched roof, if you have a flat roof, mounting on a curb is a good idea. 

A curb-mounted skylight is preferred for a flat roof over a deck-mounted skylight for several reasons:

  • Waterproofing: Curb-mounted skylights are raised above the roof’s surface, which helps prevent water from pooling around the skylight. This reduces the risk of leaks and water damage.
  • Easier Installation: Curb-mounted skylights are installed on a raised curb that is attached to the roof. This makes it easier to create a watertight seal around the skylight, as the curb provides a stable base for the skylight to sit on.
  • Improved Insulation: The raised curb provides space for additional insulation around the skylight, helping to reduce heat loss in the winter and heat gain in the summer.
  • Aesthetic Considerations: Curb-mounted skylights can be more aesthetically pleasing, as they can be designed to blend in with the roofline more seamlessly than deck-mounted skylights.

Overall, a curb-mounted skylight is a more practical and effective choice for your flat roofing system. Now, let’s move to the core of our blog post and talk about installation. 

Skylight Is Best For Flat Roofs


Steps To Replace Your Flat Roof Skylight

If your old skylight is damaged or not working properly, it’s best to replace it. Here are the steps that you can take:

Take The Necessary Precautions 

Be it a pitched residential roof or a flat roofing structure, roofing work can be difficult. So, it’s best to take precautions for your safety. When securing the ladder, ensure it is placed at a suitable angle against the roof to prevent it from slipping or tipping over. Consider using ladder stabilizers or standoffs to provide additional stability, especially on uneven or slippery surfaces. A securely positioned ladder is crucial for maintaining balance and preventing accidents.

Additionally, always wear a safety harness when working on the roof, especially when using a ladder. A safety harness will provide added protection in case of a fall and is essential for working safely at heights. Ensure the harness is properly fitted and attached to a secure anchor point to prevent serious injury in the event of a fall.

Prepare The Work Area

Before you begin the skylight replacement process, it’s crucial to prepare the work area properly. The day you are starting the work, check the weather forecast to ensure there are no impending storms or high winds. Working in adverse weather conditions can be dangerous and should be avoided.

Start with cleaning your flat roof. Remove any debris, such as leaves, branches, or tools, from the area around the skylight. This will prevent tripping hazards and ensure a clear workspace.

Remove Your Old Skylight

Now that you have prepared the area, it’s time to remove the existing skylight. Removing the old skylight is a delicate process that requires precision and care. Begin by using a pry bar to gently remove the skylight’s frame, taking care not to damage the surrounding roof membrane. It’s important to work slowly and methodically, ensuring that each part of the frame is loosened without putting excessive pressure on the roof. 

Once you remove the frame, inspect the area for any remaining sealant or debris that could interfere with the installation. Clear away any buildup and clean the area thoroughly to prepare for the new skylight.

Build The Curb For The Skylight

Now, depending on the situation, you might need to replace the curb too. To build a curb for a new skylight, you’ll need to start by measuring the dimensions of the skylight. The size of the curb will depend on the size of your skylight, whether you install one of the standard sizes or go for the custom options. Once you have the measurements, cut a piece of wood to match these dimensions. It’s crucial to leave a quarter-inch gap on each side of the skylight to ensure it fits properly. 

Install The New Skylight

Then it’s time to put the skylight on the curb. Place the skylight on top to check that it fits. 

Once you have confirmed that the skylight fits correctly, remove it from the curb and prepare to secure it in place. Use appropriate screws or fasteners to attach the skylight to the curb, ensuring that it is aligned correctly and sits flush with the curb surface. 

Waterproof The Area

Waterproofing is a critical step in the skylight replacement process to ensure long-lasting protection against leaks. After securing the skylight to the curb, the next step is to apply a waterproofing membrane around the base of the skylight. This membrane is essential for creating a barrier that prevents water from seeping into the roof and causing damage.

For flat roofs, it’s crucial to use a waterproofing product specifically designed for this purpose. After applying the membrane, allow it to cure according to the manufacturer’s instructions. 

Skylight Installation

Should I Hire A Professional Instead? 

As you can see, there are several steps involved in installing a new skylight. However, installing a skylight by yourself, without much experience, can do more harm than good. 

To ensure that both your flat roof and the skylight stay safe, hire Nortkit Roofing. Our team has years of experience installing skylights on both flat and pitched roofs and can handle your project with ease. Contact us today at (973) 396-7416

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