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Everything You Need to Know About Roof Windows

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Roof windows boost your insulation and fill your room with warming natural daylight, with clever ventilation options for a comfortable and healthy environment.

The new or replacement roof windows you select will greatly affect the finished appearance, energy efficiency, and even property value of your home, so it is important to understand your options.

Hire a Professional

Installing new or replacement roof windows is not a DIY job. It requires specialist skill and experience, which unless you have yourself you should always hire a professional contractor for. Attempting to undertake this task yourself could end up costing you more in the long run. However do read on! Whenever hiring a professional installer, it is a good idea to first understand the product. The professional you hire may help you choose the right roof window for your property, but you should also have a prior understanding of your options and what you want.

Types of Roof Windows

There are different options concerning how the window opens, including: Centre Pivot, which opens out from a hinge half way down the window; and Top Hung, which opens from a hinge at the top of the window. Each style offers different benefits. It is a good idea to get some advice in your local Topline store as to which suits your needs best.

You must also choose wood or uPVC for the window frame. Wooden frames provide a traditional look and are now coated in multiple layers of specialist varnish for prolonged protection. White uPVC is growing in popularity and can better withstand moisture and fluctuating temperatures, making it the ideal choice for the Irish consumer.

For out of reach ceilings, an electric or solar powered roof window option is available, e.g. Velux Integra. This will allow you to open and close the window with a remote control; some even feature automatic closing upon the detection of rain.

Roof Slope

Depending on how flat or steep your roof slope is, different flashing kits and installation procedures will apply. Flashing provides a watertight seal between the roof window and the roof. Every roof window will require flashing. You contractor will need to assess the angle of your roof slope, your roofing material, and your choice of roof window to ascertain the flashing and installation procedures required.

North, South, East & West

When you can choose a place for your roof window, think about where the sun will be throughout the day. If the placement is inflexible, choose the right window to optimise the daylight. North facing windows will never receive direct sunlight, so choose a larger window to capture as much daylight as possible. East facing windows will receive direct sunlight in the morning, which can be nice for kitchens and bedrooms depending on your preference. West facing windows will light up in the evening, making them ideal for living rooms. South facing windows receive daylight steadily throughout the day, so this is the ideal direction for the rooms in which you spend the most time.

Insulation & Ventilation

Newer roof window models feature innovative ventilation options that allow you to enjoy fresh air in the room even when the window is closed. Velux windows feature a ventilation flap that can be opened, allowing air to circulate in through an air filter while the window remains locked. The air filter also performs as an insect filter; especially useful since the discovery of toxic spiders in Ireland!

Various window glazing options affect the thermal insulation of your roof window. Look for the U value, which is a measure of thermal efficiency. The lower the U value the better the window to help you keep your heat inside the building.


Roof windows can add up to 30% more light to a room than a standard window. This is fantastic most of the time, but installing a suitable blind is essential for when some daytime shade is required. Most roof window manufacturers also make blinds especially designed for their windows, ensuring a perfect fit. Some blinds even provide thermal benefits, offering up to a 20% reduction in heat loss, e.g. Keylite. Blackout blinds are ideal for bedrooms and will help you achieve better quality sleep.

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