# Window Mullions



## JackOfAllTrades (Jan 8, 2008)

Are windows with center mullions weaker than a window without it? Some large window sizes require a center mullion or the other option is that one has to get TWO windows instead of just one. 

Do center mullions cause any leak issues?


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## kwikfishron (Mar 11, 2010)

I’ve never have had any issues with mullion leaks and have installed plenty of them (Milgard) front row too the Pacific which is probably as good of a test you’re going to get.

A mullion is simply the piece that joins two windows together, so with the one large window you mentioned is actually two windows joined together.

There is an up-charge for a mulled unit so purchasing two separate windows would likely cost less up front but maybe not after you figure in the extra framing and trim work involved.

I’m not sure what you mean by weaker, there is nothing structural about the mullion other than joining the two windows.

For me when deciding whether to order a mulled unit or not usually has to do with what I want the finished product to look like trim wise. 

With separate units that have a framed post in-between you may be able to get by with a smaller header.


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## Duckweather (Mar 26, 2012)

If you are using wood windows they can be made with a stud pocket between. That is for header support on large or multiple units, not window strength. never tried to get one with vinyl or aluminum, the nailing fins usually overlap so I just put one jack in the center and increase R.O. by 1-3/4". Then you do have to fill the space between. But again only if header needs the support.


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## Windows on Wash (Aug 30, 2011)

Never had and issue with a mullion.

The zero mullions are better than the H style but both, if installed correctly, are totally fine.


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## JackOfAllTrades (Jan 8, 2008)

Have you ever seen a window installed with brackets instead of a nailing flange?




















European windows do not have a nailing flange like American windows do, as they are installed recessed in the wall, not flush on the outside like American windows are. They need a bracket or they have to be screwed directly to the window buck.

BTW - That first photo, the wall is a wood SIP, hence the reason why it has OSB on the interior & exterior. A SIP is 3 times stronger than a framed 2x6 wall, 16" o.c., with OSB shearing on the exterior.


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## CarolHawks (Aug 8, 2012)

Yes I have heard about this new way of installing windows when the installer wishes to avoid putting nail holes through the casing. This Interior installation brackets provide a method for installing units. And it looks something new and different too.

windows wellington


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## oberon (Apr 29, 2006)

*bracket*

Jack,

The windows are triple pane tilt/turns it appears.

The design is euro, but are they manufactured in europe or north american? 

If North American they look like Innotech with a Kommerling extruded vinyl sash/frame components.

As you noticed I am sure, the bracket is really easy to use, it snaps into a side channel, twists into place, and once in place is secure as heck.

A number of North American companies use variations of brackets as well, especially on hurricane impact products, but those brackets are all (that I know of) screwed into the frame rather than the euro snap in design.

Nice looking windows.


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## JackOfAllTrades (Jan 8, 2008)

oberon said:


> Jack,
> 
> The windows are triple pane tilt/turns it appears.
> 
> ...


That is correct, they are triple pane tilt & turn or as some say here in the states, a reverse opening casement.

The tilt & turn locks in 7 areas when you lock the window. They are as tight as a bank vault. Even though they are residential, they come with a DP70 commercial rating. 

The advantage of the Euro snap in design is that one doesn't have to drill through the framing and once you know how to install, it makes it very easy. Plus they really secure that window to the wall. 

These windows are made by Intus in Europe and they are shipped over to the USA. They are designed for Passive House and have a *U-Value of 0.14* and they are triple pane with gas filled. 

The window profile is the thickest I have ever seen. These uPVC windows are reinforced with a steel channel and feature multiple thermal breaks. In Germany they use thicker glass than they do here in the States. 










They also make a wood/aluminum clad window:


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## Windows on Wash (Aug 30, 2011)

Nice piece. They are right down the street from me and this reminds me that I need to get by there and take a look at them.

Thanks.


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## JackOfAllTrades (Jan 8, 2008)

Windows on Wash said:


> Nice piece. They are right down the street from me and this reminds me that I need to get by there and take a look at them.
> 
> Thanks.


Let me know how it goes and what you think...


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