Skylight waterproofing essential steps and maintenance

November 22, 2023

As home improvements go, skylights are an inexpensive, noninvasive way to transform your property. Installing them doesn’t require major structural changes, like removing doors or knocking down walls: rooflights will slot neatly into your existing roof plane.

They’re the ideal way to open space, brighten dull rooms and increase a property’s energy efficiency. You’ll rely less on artificial light and enjoy radiant heat from the sun’s warmth. Newer, modern models offer a whole host of benefits that you can’t find anywhere else.

But what if your rooflight is over 20 years old? Older skylights are more likely to experience age-related faults, such as discolouration, window pane cracks, or leaks. If this sounds familiar, follow our skylight waterproofing essential tips and maintenance.

What is a flat roof window?

Flat roof windows, often interchangeably used with the term skylights, are specially designed windows installed in flat or low-pitched roofs. Unlike traditional vertical or slanted windows, these windows are horizontal and face directly upward towards the sky.

Modern flat roof windows come with a range of features. Some are fixed, serving solely the purpose of letting in light, while others can be opened for ventilation.

Advanced designs also offer features like UV protection, thermal insulation, and self-cleaning glass. With the evolution of technology, there are even smart skylights that can be controlled remotely, adjusting their tint based on the weather or time of day.

What causes a skylight to leak?

As they age, the structural integrity of older rooflights may falter: this could be because of a poor initial installation, a low-quality product, or other environmental factors, such as:

1. Condensation

Condensation occurs when moisture-laden air comes into contact with the cool surface of your skylight’s glass and forms tiny water droplets.

In certain conditions, such as very cold climates or humid rooms, condensation is more common (especially with single-glazed skylights!) The accumulated water from condensation can pool and eventually drip inside the building, mimicking a leak.

To prevent this, additional insulation can be added between the framing members and the skylight. A simple solution is using expanding spray foam, which helps to reduce the temperature differential between the indoor air and the skylight surface.

2. Poorly-installed skylight

If a skylight is not properly sealed to the roof, gaps can form between the product and the roofing material.

Due to the material’s degradation over time, these gaps can widen and allow water to seep through. There may also be issues with the rooflight’s alignment.

If the product has been improperly installed and is not aligned with the roof’s slope and structure, rainwater will not drain correctly. Eventually, water will pool on and around the rooflight and cause leaks.

Using unqualified installers or attempting a DIY installation without the proper qualifications can result in substandard workmanship.

You may not use the materials correctly, fail to follow manufacturer guidelines, or inadequately secure the skylight to the roof.

3. Leaks

Over time, the frame of an older skylight (whether made of low-quality metal or even wood) can deteriorate. Degradation can be caused by exposure to the elements, temperature fluctuations, and general ageing.

When the frame loses its structural integrity, it can no longer hold the glass as tightly, leading to small gaps where moisture can seep through and enter your living space. If the frame doesn’t fail, your rooflight’s glass may first.

It’s possible for rooflight glass over 20-30 years old to suffer heavy damage from external factors (e.g. falling branches or debris during storms).

Even a small crack can compromise the skylight’s integrity; once it is breached, water will leak through (especially during periods of heavy rain). These situations require immediate repairs or replacement.

4. Roof flashing

Roof flashing is a key component to preventing water leakage: it’s a sealant placed at the junction between the skylight frame and the roof, designed to channel water away.

When this flashing is damaged, such as from cracks, corrosion, or general wear and tear, it compromises its ability to prevent water ingress.

Plus, if you work with inexperienced installers or even try to secure the flashing yourself, the rooflight may not be securely sealed.

How to waterproof a flat rooflight

In the past, people used several at-home waterproofing methods to make the rooflights leak-free, including;

1. EPDM rubber waterproofing

EPDM stands for Ethylene Propylene Diene Monomer, a type of M-Class rubber known for its durability and waterproofing abilities. EPDM is supplied in continuous sheets (usually 1 mm – 25 mm thick) and can be cut into pieces with a utility knife.

With precise measurements, you can seamlessly cover your joins or seams, protecting them against environmental conditions like heavy rain and UV rays.

EPDM can be installed using an adhesive (like contact or water-based adhesive) or a fleece back system for cushioning over imperfections. It’s fairly easy to install, often manageable as a DIY project, and requires little to no maintenance over its lifecycle,

2. Elastoform tape application

You can also use Elastoform tape, a flexible adhesive material that’s easy to cut to size and position on the corners of your skylight. After applying a rubbing primer and allowing it to dry, you can install the tape.

Start from the top of the skylight and stretch it downward to cover the entire area. To seal the Elastoform, apply pressure using a seam roller to ensure firm and even coverage.

3. Leave it to the professionals!

The safest, most effective way to ensure your skylight is waterproof is with a replacement!

Leaking is one of the calling cards of a failing rooflight, so if you notice regular droplets or water puddles in your living space, it’s time to invest in a modern product.

At TuffX, we have over 25 years experience manufacturing and installing top-quality rooflights.

You can find our weather-tested skylights in homes and businesses across the UK, flooding properties with natural light and protecting them from the elements, too!