A Mullion Post is the Way to Install Two Windows

What’s a mullion post, and we should you care about it?

If you have a wide window opening, one obvious way to span this distance is to buy a wide replacement window. But specialty-size replacement windows really drive up the cost of your window project. One way to get around this is to use a mullion post to install two windows in that opening.

For example, instead of installing a 60″ wide window in that space, you may decide to install two 27″wide windows side by side. Between the two windows would be a mullion post. The mullion post would cover the rest of the 60″ distance; tie those two windows together; and provide structural stability.

In fact, a mullion post isn’t just a good idea when installing two windows side by side; it’s a necessity.