HomeA flying mullion window is a specific type of double-sash window without a central mullion. When both sashes are opened, an unobstructed passage is created – ideal, for example, for access to a balcony or terrace. When viewed from the outside, a closed flying mullion window and a window with a mullion are almost indistinguishable – the difference is only apparent upon opening.
How Does a Flying Mullion Window Work?
The active sash (with a handle) opens and tilts like a classic window.
The passive sash can only be opened after the active sash has been opened – using a hidden mechanism inside the frame. The passive sash cannot be tilted into the ventilation position.
Advantages of a Flying Mullion Window
Once opened, nothing obstructs the view or passage.
More cost-effective compared to a window with a mullion.
Disadvantages of a Flying Mullion Window (compared to a classic double-sash window with a mullion)
Only one sash is fully operable.
The passive sash cannot be independently tilted into the ventilation position.
Insect screens cannot be installed on both sashes.
Lower structural airtightness.
Dimensional limitations.
Our Practical Perspective
Customers often ask us:
“I want a double-sash window – should it be a flying mullion type?”
Our answer is:
“Will you definitely use both sashes? Or is one main sash sufficient for you? If you want both sashes to be fully openable and tiltable, each with its own handle, ventilation position, and the option for a separate insect screen, a classic double-sash window with a mullion will be more advantageous for you.
Furthermore, when changing the room layout, you can adapt which sash will be primarily used – thus ensuring your comfort for the future as well.”
In other words: the flying mullion solution is elegant, but not always the most practical – it depends on how you will actually use the window. We will gladly help you choose the right tailor-made solution.
Interesting Fact: Why is it called a “Stulp”?
Perhaps it’s no surprise that the word ‘štulp’ is not of Slovak origin. It comes from the German term “Stulp,” which in construction terminology refers to a movable connecting element between two sashes of a window or door. Etymologically, it goes even deeper – to the Old Germanic root for a post or support. It was adopted into Slovak as a technical term, which is still used today, especially in window manufacturing.
Conclusion
A flying mullion window is a stylish and functional solution where an unobstructed view and direct, barrier-free passage are important to you. On the other hand, a classic window with a mullion will provide you with full use of both sashes – especially if you plan to ventilate frequently and desire maximum comfort.
It’s not just about design, but also about daily use.
If you are hesitant, contact us – we will gladly advise you on what will be best for your project.
Do you need advice on choosing the right type of window? We are here for you – reliably, professionally, and with a personal touch. Contact us to arrange a meeting.
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