Weight bearing ability of mullions in Vinyl windows group

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woozy
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Weight bearing ability of mullions in Vinyl windows group

#1 Post by woozy » Mon Jul 18, 2016 3:12 pm

Old wood window hole had 1 small wood window on both sides of a picture window. And there were a wooden support post from sill to header between each small window and picture window. If replace with 3 united equal size vinyl windows will one mullion between each window; then will those mullions be able to support weight of header formerly supported by the 2 vertical wood support posts between those windows. Width of old window hole is about 92-93 inches across and height about 54 inches. Thanks much.

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Windows on Washington
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Re: Weight bearing ability of mullions in Vinyl windows group

#2 Post by Windows on Washington » Mon Jul 18, 2016 7:39 pm

Not usually. There are options for structural mullion, but they are normally for horizontal applications.

What is the thickness of that wood that is in between the units?

While it was probably never intended as a structural component, we do see openings like this that are unintentionally carrying some load across them.

Why not just do 3 inserts if you are concerned?

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Delaware Mike
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Re: Weight bearing ability of mullions in Vinyl windows group

#3 Post by Delaware Mike » Tue Jul 19, 2016 5:49 am

The interior mulling should have a simple to remove cover to visually examine if what you're perceiving to be framing members. I would expect to see the flanking window frames simply mulled to the picture window frame. If you have currently have wood windows they leave the factory attached together as a single factory unit.

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HomeSealed
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Re: Weight bearing ability of mullions in Vinyl windows group

#4 Post by HomeSealed » Tue Jul 19, 2016 11:15 am

Can you take a picture of the existing unit? Your comments sound like there is a cavity between the windows that has a stud running through for support. If that is the case, then it would not be advisable to remove that. On the other hand, if there is an empty cavity, or the "posts" that you are referring to are nothing more than the existing side jambs mulled with a cap, then removal is typically no problem and is very common.

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Re: Weight bearing ability of mullions in Vinyl windows group

#5 Post by TheWindowNerd » Fri Jul 22, 2016 7:09 pm

You need more info than what is in the existing mullion.
What is the load form over the top of the opening, what is the header? then you can know what needs to be done.
The sure thing is to leave the stud framing or replace in kind if you do not know the other info and do not feel like gambling.

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Re: Weight bearing ability of mullions in Vinyl windows group

#6 Post by Guy » Sat Aug 06, 2016 2:11 pm

Woozy these type of Windows pop up all the time. I've probably done about two dozen of them. In each case the vertical 2x4 running up through the mull cavity had NO structural relevance. They were mainly installed for the attachment of mull casing trim between the wood windows. Since back in the day we built these openings one window at a time. They weren't mulled together very often in the factory. We just did it in the field. Usually the existing header is always bearing the entire load across the opening. I always removed the mull cover and checked the header before I ever through out options. I could always get up above that 2x4 post to verify a continuous header! If it's not continuous I'd recommend getting an engineers opinion before proceeding. Getting structural mullions for any opening sucks. I'd order one complete unit mulled in the factory with a new jamb box! Good Luck!!!

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