Factory Mulls

dctonycMay 28, 2014

I am in the process of getting Okna 500 windows installed to replace old wood windows in my house. One of the companies told us that for the two or three double hungs that are next to each other, they can do "factory mulls", which might be cheaper than two or three standalone windows and also may be better structurally. I asked that to another company and they said no, they can't do that, as the combined width can't exceed 52 inch or so. My question to the forum is whether or not I should ask for factory mulls. Thank you all in advance.

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It really doesn't make any difference IF the installer is solid. A good installer mulls the windows in the field just like they do in the factory.

    Bookmark   May 28, 2014 at 11:18AM
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The mullion clip lock can be done factory or in the field.

    Bookmark   May 28, 2014 at 9:23PM
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It sounds like you are asking about mulled units (whether done in factory or on site) compared to individual units installed within the homes existing wood mulls? Is that correct? If so, it is really a matter of preference. A mulled unit will net you more glass area and a streamlined appearance, as well as minimize the areas for potential air leakage. Leaving the wood in there and installing individual windows preserves some character and some people prefer that...
If your question was in reference to factory mull vs field mull, I'd concur with the other pros, no difference. There is a size limit that most manufacturers have for shipping purposes, however it is FAR more than 52".

    Bookmark   May 29, 2014 at 10:59AM
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Thank you all very much. I was indeed asking about mulled units. Sounds like that should be the way to go in our case.

    Bookmark   May 29, 2014 at 1:32PM
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Be carefull. The existing stud pockets might be structural. I've seen many shoddy replacement window jobs where the installers took these studs out and used mulled units. The headers were not sized to span the new openings created. Three stand alone units will be stronger than factory mulled units in almost every case....

    Bookmark   June 5, 2014 at 3:22PM
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While the studs may not be defined as load bearing, many are functioning as such unintentionally.

Be careful with the larger units.

    Bookmark   June 6, 2014 at 10:00PM
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That would only apply to units that actually have studs between the windows, as opposed to the majority that I see where you simply have wood buck frames strapped/mulled together and set in an RO. Perhaps this is a regional practice, but that is 9 out of 10 times around here... If there are studs between the units I'd generally like to see them left in as KSC1 referred to, even if there is a continuous header. That is good advice. If no studs, mull removal is no worry.

    Bookmark   June 7, 2014 at 2:46PM
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