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Flat Roof Windows Buying Guide

Considering modern architectural design and home renovations, flat roof windows have been proven to be an absolute masterpiece rather than just a trend – they're essential in transforming spaces. 

Whether you're looking to illuminate your living room with natural light, create an inviting rooftop terrace, or enhance your kitchen with a stunning sky view, flat roof windows offer a unique and stylish solution.

However, with many available options today, choosing the perfect flat roof window takes time and effort. Factors like size, material, design, and energy efficiency all come into play, and making the right decision requires careful consideration.

This ultimate flat roof windows buying guide will help you discover and pick the right flat roof skylight window for your property. 

What are flat roof windows?

Flat roof windows are specially designed on flat or low-pitched roofs to bring natural light into interior spaces. These windows, often called roof lights or skylights, are typically flush with the roof's surface and have a sleek, modern design. 

They come in various shapes and sizes, including square, rectangular, and dome, and can be fixed or opened for ventilation. 

Flat roof skylight windows are made with durable materials like double-glazed glass to ensure energy efficiency and weather resistance. 

Suitable for pitches as low as 3 degrees, windows for flat roofs enhance the aesthetics of a building, create a sense of openness, and improve the overall ambience of rooms by maximising daylight penetration.

Benefits of installing flat roof windows

Flat roof windows, also known as roof lights or skylights, offer several benefits that can significantly enhance the functionality and aesthetics of a building. Here are some of the critical advantages of installing flat roof windows:

Increased natural light

Flat roof windows allow more natural light into your home, which can improve your mood, energy levels, and overall well-being. They can also help to reduce your energy bills by reducing your reliance on artificial lighting. VELUX flat roof windows are best for bringing sunshine in.

Improved ventilation

Flat roof skylight windows can help improve your home's ventilation by allowing fresh air to circulate. This can help reduce humidity and condensation, leading to mould growth and other problems.

Enhanced aesthetics

Flat roof windows can add a touch of modern style to your home. They come in various styles and finishes from renowned brands such as Duratech, so you can find one that matches your home's décor.

Increased security

Windows for flat roofs can help improve your home's security by allowing you to see what is happening outside. They can also make it more difficult for burglars to break in.

Lowered noise levels

Flat roof windows can help to reduce noise levels in your home by providing a barrier between the inside and outside. This can be especially beneficial if you live in a noisy area.

Extended lifespan of your roof

Flat roof skylight windows can help extend your roof's lifespan by protecting it from the elements. They can also help to prevent water damage and leaks.

Choosing the correct type of flat roof window for your home

Multiple flat roof windows are available in the market, each with advantages and disadvantages. The right window type for your property will depend on your specific needs and requirements.

Here are some of the most common types of windows for flat roofs:

Fixed windows

Fixed windows do not open, so they are a good option for areas where ventilation is not a concern. They are also suitable for homes with young children or pets, as they cannot be opened accidentally.

Vented windows

Vented windows can be opened to allow fresh air to circulate. They are a good option for hot or humid areas, as they can help reduce condensation and mould growth.

Roof lanterns

Roof lanterns are large, free-standing windows that can provide a lot of natural light. They are a good choice for rooms that need a plethora of sunshine, such as kitchens and living rooms.


Domes are round windows that can add a touch of style to your home. They are a good option for rooms requiring more light but can also be used in smaller rooms to create a focal point.

Sun tunnels

Sun tunnels are a type of skylight that uses a reflective tube to bring natural light into a room. They suit rooms with little sunshine, such as basements and bathrooms.

When choosing a flat roof window, it is essential to consider the following factors.

Size and location

The window should be the right size for the space and where it will get the most natural light. Consider the motive of your roof windows: Is it to bring more sunshine? Or is it to create an airy space? 

Roof style

Not all flat roof windows are suitable for all types of roofs. You will need to consult with a roofing contractor to determine if your chosen window is compatible with your roof. 

You may choose fixed, vented, round or dome windows, whatever suits your roofing needs. It is essential to consider whether you need planning permission for a specific type of roof window in your area.


The window should withstand the environment in your area. For example, if you live in a hot climate, you will need a window to prevent heat from entering your home.

When facing the UK's unpredictable weather, including extreme heat, hail, storms, heavy rain, and strong winds, it's crucial to evaluate which type of roof window is best equipped to withstand these conditions.


Flat roof skylight windows can range from a few hundred to thousands of pounds. You will need to set a budget before you start shopping. 

At JJ Roofing Supplies, flat roof skylights' costs range from £132 to £7000.

Once you have considered all these factors, you can start shopping for your home's right flat roof window. Be sure to get quotes from several different companies before making a decision.

Which roof window brand to choose from?

The choice of a roof window brand depends on your specific requirements. 

VELUX is a renowned, trusted choice, offering various high-quality energy efficiency and innovation options. 

Fakro is also reputable and known for its durability and performance. Mardome and Coxdome are budget-friendly options, offering decent insulation and ease of installation. 

Korniche and Atlas Roof Lanterns enhance aesthetics and bring natural light for stylish roof lanterns. Duratech offers reliable and affordable options. 

Ultimately, your decision should consider budget, design, energy efficiency, and professional advice to match your unique needs.

Installing flat roof windows

Even though it sounds big, flat roof window installation is relatively easy. If you are a DIYer and want to save on costs to hire professionals, follow the simple steps, and you will be able to install the flat roof windows on your property.  

Follow our A Brief Guide to Roof Windows blog to install flat roof windows. 

However, it would help if you remembered that installing flat roof windows involves structural work and may require permits and compliance with local building codes. It's essential to consult with a professional or local authorities before starting the installation.

Most manufacturers provide their guide about installing roof windows and the steps to follow. 

Adhering to these procedures represents the most effective approach to guarantee that you acquire a window that is both safe and secure, well-equipped to withstand the year-round environmental challenges it will encounter.

Practical installation considerations for flat roof windows

Consider the roof slope: The roof slope will affect the type of window that you can install. If you have a steep roof, you will need a window designed for a pitched roof. You will need a window designed for a flat roof if you have a flat roof.

Use the proper flashing: Flashing is a waterproof material that helps to seal the window to the roof. Using the correct type of window flashing for your roof and window is essential.

Seal the window properly: After installing it, it is essential to seal it properly to prevent leaks. Use a high-quality sealant and apply it evenly around the perimeter of the window frame.

Test the window for leaks: Once it is sealed, you should test it. Pour water around the edges of the window and check for any signs of water seepage.

Post-installation, maintenance and cleaning regimen

Once you've successfully installed your roof windows, it's crucial to uphold their longevity through proper maintenance. To keep them in excellent condition, use a standard cleaning spray and a cloth to eliminate dirt and grime.

We encourage you to visit our comprehensive guide for an in-depth, step-by-step manual on cleaning Roof Windows.

It's essential to keep in mind that regular window cleaning should be conducted at least once a year. This promotes proper ventilation and ensures the extended lifespan of your roof windows.

Do you need planning permission for installing flat roof windows?

Typically, planning permission is unnecessary. However, if your development extends beyond the highest point of the roof and surpasses a distance of 150mm from the current roof plane, you must consult the installer. 

If you need more time, you can secure a 'permitted development' confirmation from your local council through a letter. This confirmation clarifies whether your project falls within or outside the approved guidelines. While not mandatory to commence the work, obtaining this confirmation can provide long-term peace of mind.