ᐅ Double doors with or without a mullion — what’s the difference?

In our new build, both the kitchen and the living room will have double doors leading outside without a central mullion. What exactly does that mean? There must be something in the middle; the glass panes can’t just be right against each other. Due to the size of the windows, the manufacturer does not provide a warranty if we choose triple glazing because it would be too heavy. So, we are opting for double glazing instead.

Terrace door with French door style: the window trim is, of course, present, but there is no mullion in the middle where the window opens.
Advantage: 2 meters (6 feet 6 inches) fully open. It is not recommended to exceed a width of 2 meters (6 feet 6 inches).
@11ant?

Heidi1965 schrieb:

Double doors without mullion

It’s usually called “double-leaf with a flush mullion,” where the rebate of the leaf that opens second is arranged in the opposite direction. That means the first leaf to open closes against the second leaf with rebate-to-rebate in the middle of the full opening. A mullion refers to a fixed post between the two opening leaves, which, in my opinion, largely defeats the purpose of having double doors.

Heidi1965 schrieb:

Due to the size of the windows, the manufacturer does not provide a warranty if we choose triple glazing because they become too heavy.

Wow, how large are they supposed to be?

ypg schrieb:

Advantage: 2 meters (6.6 feet) opening fully. You shouldn’t go wider than 2 meters (6.6 feet).
@11ant?

If you like a classic symmetrical split, I recommend a width of 226 cm (89 inches). A rough opening width of only 1 meter (3.3 feet) is a bottleneck with a tray or laundry basket and at best inconvenient. If you only have 2 meters (6.6 feet) width available, I recommend an asymmetrical split so the first opening leaf can be 113 cm (44 inches) wide. I only recommend sliding doors starting at widths of 251 cm (99 inches). I’d be happy to give more specific advice if the overall situation (the entire room with all the windows) is shown here.

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I also don’t understand why triple glazing is not possible.

It’s important to know, as has been mentioned briefly in other posts, that you cannot open both sashes independently. This means there is always one “leading” sash. Whether this is on the left or right side should be carefully considered.

Unfortunately, we discovered that our window company only fits these doors with one handle (on the “leading” sash); the other sash is unlocked from inside the frame and can then be opened. We are currently trying to get used to the asymmetric look.

hausnrplus25 schrieb:

these doors are only equipped with one handle

Isn't that normal?

I only know it that way, too. We have a French door on the terrace and a window like that in the kitchen. We used to keep the kitchen door locked at night, but you get used to it.