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Skylights are a natural and perfect solution for interior ventilation and lighting. They are similar to windows but are on the roof. They are designed to be sturdy, which allows them to withstand almost anything, including extreme weather conditions. However, skylights can break and start to leak, so it's essential to know how to seal them.

Different circumstances make them susceptible to leakages, and it's essential to know how to avoid these issues in addition to fixing them. You'll find all you need to know in this article, so read on.

Types of Skylights

Skylights are grouped according to their functions, and there are two main types. They also differ in how they are repaired, which is why you need to know how each type works. The two different types of skylights are:

Vented skylights

These are skylights that can open and are designed for ventilation and lighting. Houses with open skylights also enjoy more privacy since you can always open them, not the windows. They are also great for controlling moisture in areas like bathrooms and kitchens, where a build-up of condensation is likely.

Fixed skylights

The second type of skylight doesn't open and is mainly designed for light control. Fixed skylights are installed on ceilings, especially the higher ones, and generally last up to 15 years, which is longer than vented skylights. When leaks occur in this type of skylight, it is usually at the edges, especially when their panes are in poor condition.

Build of Skylights

As mentioned earlier, skylights are similar to windows, but they are mounted on roofs with flashings to stop leakages. Modern skylights are designed with channels to direct water away, and if there's a fault in your skylight, it's likely to be from the panes or the flashings.

The chance of leaks occurring is higher with fixed skylights than with vented skylights. This is because the faults with vented skylights are easy to identify, unlike those with fixed skylights. Also, fixed skylights are not permanently fixed within reach and can get damaged at the panes and flashings.

Causes of Leaking Skylights and How to Seal Them

There are different reasons why your skylight is leaking, and some of the common reasons are:

Faulty skylight

If you notice your skylight opens, the first thing to check is the frame for signs of mold or deterioration. These are indications that the skylight is not sealed correctly; to fix this, you only need to replace the gasket. Another likelihood is that something is obstructing the skylight. This can be debris or other small particles, and removing them could fix the leak.

Faulty roof flashing

If skylight defects are ruled out, consider checking the flashings for faults. Leaks coming from the roof slopes are a lot easier to fix. However, it might be more complicated if it's coming from the lower parts of the roof, as finding the source of the leak is tricky since water moves along the roof deck.

Leaks caused by damaged or faulty roof flashings can be identified by assessing the physical condition of the flashing. Generally, broken or curled flashings allow water to pass through easily.

Roof leaks

With roof cement, you can fill the gaps between roof leaks, especially from holes in the roof. You can either hire a professional for this or do it yourself. However, if the leak persists after this, it could be from other parts of the roof.


One of the things to look out for when inspecting your roof's skylight is signs of moisture on the glass. This could result from leaks, especially if you notice that they accumulate at a particular spot. The best method to handle condensation is by allowing fresh air circulation in your house. With fixed skylights, you can use a fan to circulate fresh air, while vented skylights only need to be opened.

Fixing Leaking Skylights

To fix leaking skylights, you must go through a few steps first. The first thing to do always depends on the type of skylight you have, but this mainly involves determining the cause of the leak.

As mentioned earlier, vented skylights don't usually have issues, unlike fixed skylights. Below are some of the things to do when fixing a leaking skylight:

  • Check to ensure that the vented skylight is closed correctly.
  • Check for debris around the edges and hinges of vented skylights. This can alter the functioning of water seals around these areas, resulting in leakages.
  • Ensure that the roof flashings around the skylight are in good condition.
  • Check the skylight panes for cracks, no matter how small.
  • Verify the state of the gasket around the frame. Damaged seals make it easier for water to pass through.

Common Fixes for Skylight Leaks

In addition to everything above, here are some common fixes for skylight leaks:

Sealing leaking parts

Sealants can be used on both windows and skylights to prevent water from entering. Like other items, it's crucial to replace them as time passes because the most common problem with skylights is deterioration. Sealing and caulking are among the most straightforward fixes you can do independently. For this, you can use silicone caulking to seal the leaks.

Reinstalling the flashing

Flashings are generally designed to be leak proof, especially when correctly built. They are a good investment for skylights, as they help to prevent damage caused by leakages. However, it's vital to ensure they are not nailed to sensitive areas when installing them.

In cases where you have rusted flashing or the nails decay, the best thing is to remove the flashing and roof shingles. For this, it's generally best to hire a professional for roof repair and skylight repair.

Use the correct materials

It's easier for roofers to create their flashings from aluminum, which is generally a cost-effective alternative. Another strategy that roofers employ is the use of caulk at corners to prevent water from coming in. However, caulking only lasts five to ten years and may be expensive in the long run.

Check the insulation

Another thing to check if you suspect a leak in your skylights is the insulation of your home. Warm air generally flows freely if there's little or no insulation, which can build up the humidity in your home. This can lead to the formation of condensation, thereby resulting in leakages.

Reseal the flashing

In a case where the source of the leak is from the flashing, you can use a caulk gun and the correct sealant on your roof. The recommendation is to use an adhesive created for roof flashing for the best result. If you notice that the old caulk has started deteriorating, it's advisable to remove loose debris before applying the sealants.

Replace the skylight

For cracked skylight glass, the best thing to do is to get a replacement. It's best to do this as fast as possible because cracked skylights can worsen under extreme weather conditions. Regardless of the severity of the crack, the best thing to do is to get a replacement whenever you notice cracks on your skylight.

Professional Skylight Repair

The importance of sealing a skylight cannot be overemphasized, which is why we have provided different ways to identify and fix issues that could cause leakages in your skylight. A key thing to remember is that a building with a faulty skylight is at more risk of damage.

Another thing to note is that ignoring a faulty skylight could cause other issues like damage to furniture, chipped paint, leaks in the ceiling, the growth of mold, and the development of rot. All of these issues can affect the structural integrity of your house.

Apart from knowing how to fix these issues, it's also essential to perform regular maintenance to extend the lifespan of your skylight further and avoid future problems. For the best results, reach out to a professional to help with your sloped or flat roof skylight issues or even a roof replacement if you need one.

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